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the Southwest, enjoying a prosperous business. His residence is located on Central Avenue, where he owns a line two-story brick house.
DR. GEORGE R. HILL, physician and surgeon, was born in 1841 in Madison county, Missouri. His father, John, was a native of Cumberland county, England, who came to America in 1829, and settled in Madison county, Missouri. His mother's maiden name was Jane Robinson, also a native of England. Dr. George R. Hill was reared and educated in Madison county, Missouri, and studied medicine under Dr. J. C. Griffith, of Fredericktown, Missouri. He attended lectures at the St. Louis Medical College. He was in the Confederate army from 1861 until 1864 as a si)ldier. At the battle of Potosi, Missouri, he was wounded and taken prisoner, and remained on parole until 1864, when he joined the army again as assistant surgeon, and remained until the surrender of Lee, He practiced medicine in Madison county until 1872. In 1873 he came to St. Clair county, Missouri, and in 1876 removed to Carthage, where he has remained in practice. Since coming to Jasper county be has served two years as county piiysician. He is a member of the medical society and also of the Masonic order. He was married in October, 1871, to Miss Maud Belle Sandidge, of Fredericktown, a native of Mississippi. They have three children living and two deceased. Like most of the Hills whom we have had the pleasure of meeting, the doctor is of English ancestry, and belongs. to a sturdy and long-lived race.
PETER HILL, dealer in sadd'es, harness, and boot and shoe-findings, Carthage, Missouri, was born in 1832 in Franklin county, Virginia. His father's given name was Wilson, a native of Virginia, as well as his mother, whose maiden name was Nancy Winfrey. The Hill race probably sprang from a common stock in England prior to the Revolutionary War, and at this day and age scarce!}^ a township can be found in the United States but that possesses a Hill. Peter Hill's ancestors are no exception to this general rule. The Hill race, so far as observation and experience extends, represents them as a strong, hearty people, full of enterprise and good morals. In stature they are stout and of good height. Peter Hill was reared in Virginia, and learned the saddlery business in Christiansburg, Virginia, where he^afterwards Engaged in general merchandise for some j^ears. In 1861^he removed to Cincinnati, Ohio, where he remained about one year, after which he went to Peoria, Illinois, where he remained until 1866. He came to Jasper county in 1867 and settled in Carthage, and in that year purchased a house and lot, where he is now engaged in business. He owns the largest harness and saddle shop in Carthage, and has been eminently successful by industry, honesty, and fair-dealing, and now carries one of the
CITV OF CARTHAGE. 349
largest stocks of harness and leather goods in the country. He served on the board of trustees before the city charter, and was the first mayor of Carthage in 1873. Mr. Hill was married in October, 1867, to Miss D C. Hess, of Michigan. They have two children, Rilla Y. and Cora C, and one child deceased. Mr. Peter Hill is widely known throughout the county, both in a business and social way, for geniality and general business conrtes}'. |
of war, rifes glaringly to view, mounted pa trophies: the wreck of
nations; hence hiftory, to a feeling mind, will appear little more than a Catalogue of human Woes. In one page we often fee thoufands devoted to the fword, and the vitor’s triumph raifed at an ex- Pence of blood which a remote: nation mourns with floods of tears ;. while peace, fixed Only to particular happy {pots, as Arcadia and the romantic golden age, the fweer intervals of ace, which all nations have Probably enjoyed a greater fhare of than a meer fuperficia] view of hiftory would encourage us to believe, thefe have often been io
eftablifhed for the reception and fupport of |ivin creatures, ther were the animals created, and laftly man, Ip a@ Kate of innocence our
ee,
ilamities epraved was inward of = glory, on, and s, feems account be ac-
e their
e good pfopher \fbandthefe
e man
more thoun ex= ears 3. d the naficial been
ated ntly her nce our
‘flain by the hands of his brother the wretched Cain.
‘flroyed. “Noah and his family only furvived the flood, of all men liv-
eck of |
S, 1. SUCCESSION OF EMPIRES, 165
our firft parents lived, and were happy, till by their difobedience they loft their peace, and were driven from their blifsful manfions in the Garden of Eden into the wide world, now rendered a wilder~ nefs by their lamentable fall, The On of this couple foon proved themfelves the branches of a depraved ftock ; and Adam with his confort lived to fee among other melancholy effeéts of their woeful declenfion from the truth, the untimely death of the pious Abel,
Not two thoufand years after the creation, the earth was corrupt and filled with violence, and it was decreed that man fhould be de-
ing; they, with the creatures after their kind, were preferved in the ark from the devaftation of the univerfal deluge.
2. Origin of different Nations and Tongues] But the offspring of ‘Noah feem to have foon forgot this awful judgment; they attempted to build a city on the plain of Shinai, and a tower whofe top might reach unto heaven, and to eftablifh to themfelves a name ; their vain defigns were fruftrated, their language confounded, and they themfelves fcattered over all the face of the earth. This feems to have been the beginning of the different nations; tongues and people upon earth. If it were poffible ‘now to.take a retrofpective view of the world at that day, it appears likely that we. fhould fee it peopled in parts widely remote from each other, by .a number of families fhut out from all communication -with each other, -ftill more by difference of language than by diftance of place *.
Languages and people appear to have continuaily AuSiuated fince «mankind firft became divided into nations. Sometimes neighbouring nations have, from their vicinity, naturally commixed in fpeech and manners ; often they feem to have rudely jumbled together in the diftraction of war, fometimes a people has been rent in pieces by intef= tine divifions, at othe s they have been obliged to bow to a foreign yoke ; generally the conquerors have impojed, together with their government, their language and their manners, yet fometimes the rude ravagers of a refined and ingenious people have thought it worth their while to copy the manners and improvements of the vanquifhed.
3. Remarks.] Were all the records of hiftory complete ia information, and to be depended on as true, to declare the complicated revolutions of all nations, either by defcription or delineation, would be a tafk as perplexing to execute as tedious to perufe: but from adulation or envy the deeds of men have been often mifreprefented in their own time, and faithful hiftorians eould only afterwards glean up the truth by probable conjecture. In this work a general view of the fucceffion |
It is true that αὐτῶν seems to refer to the stars, not to their spheres, and that we are at liberty to picture with KAMPE (Erkenntnissth. d. Arist. 39 sq.) each individual star as animated by a spirit; but the passage does not compel us to do so, forif the spheres are animate the stars which are part of them must share their life and action. Elsewhere, however, Metaph. xii. 8 (see p. 501 sq. infra, and cf. previous note), he expressly says that there cannot be more eternal unmoved beings than there are spheres, and this is only what we should have expected from him, since it is only from the movement of the stars that he infers, in the way indicated in the preceding note, the existence of such beings. Moreover, it is only the spheres, and not the stars, which are said by him to be moved. It is only these, then, that have ‘souls’ of their own, or, to speak more strictly, it is only these which
are united severally to spiritual beings which stand in the same relation to them as the human soul does to the body which it moves without being itself moved (see infra, vol. ii., init.). De Celo, ii. 2, 285, a, 29: ὁ δ ̓ οὐρανὸς
So 284, Ὁ, 32; cf. Part. An. i. 1, 641, Ὁ, 15 sqq. ΑΒ, however, - the mover of the highest sphere lies outside the world and is unmoved, Plato’s conception of the ‘ world-soul ’ (which, indeed, Aristotle expressly rejects, see p.459, n. 5) is as inapplicable to it in its
relation to its sphere as it is to
the other spheral spirits in their relation to theirs.
1 Aristotle denies that there is any ‘ void’ (see p 433, sq. supra), and accordingly conceives not only of the astral spheres but of all the others, even the lowest, as in immediate contact with one another. Meteor. i. 3, 340, b, 10 sqq. 341, a, 2sqq.; De Colo, ii. 4, 287, a, 5 sqq.
2 Cf. pp. 473 and 478, supra; Phys. iii. 5, 206, b, 30 sqq. ; De Calo, i. 6 init. ii. 4, 287, a, 8, and elsewhere,
PHYSICS
spheres, that the terms aboye and beneath are applied to opposite points in the circumference, and consequently that we come to speak of right and left, front and back, in the world. In this case, reckoning from the sphere of the fixed stars, we call the southern half of the globe the upper, reckoning from the planetary sphere,
the northern.’
4 See De Curlo, ii. 2 (of. Phys. passage just referred to) and the
Each sphere has its own peculiar
motion will be that which carries the point in the periphery which received th
lucid explanation in Βύσκη, D, has
osm, Syst. d. Platon, p. 112 sa The differences here spoken οἱ apply only to motion, and aie fore properly only to that which is living and self-moved; to such the upper is (285, a, 23) τὸ ὅθεν ἣ κίνησιν, the right hand τὸ ἀφ ̓ οὗ, the front τὸ ἐφ ̓ ὃ ἡ κίνησιν. (CE. Ingr. An. 0. 4, Τοῦ, Ὁ, 18 sqq.) ΠῚ we apply this to the world, that is the right side of the πρῶτον οὐρανὸς from which its motion proceeds--in other words, the east. This motion is conceived of (285, b, 19), as it was by Plato (see ZELL. Ph. d. Gr. i. 684, 1), as proceeding in a circle towards the right, as when in a circle of men anything (as, for instance, the cup or the talk at table, PLaTo, Symp. 177, Ὁ, 214, B, C, 222, &, 223, 6) is passed along ‘by each to his neighbour ontheright, The πρῶτον
is therefore represented (285, a, 31 sqq.) as standing inside the circle of the heavens in the line of its axis, touching one of the poles with its head, the other with its feet, and as giving the ball at some point upon its equator the gua with its right hand which sets it spinning. The natural direction of such
VOL. 1.
Somonirenteae ete axis in front of him: in other words, that which from the right in a forward direction and thence to the left, This, however, will be the case with the motion of the sphere of the fixed stars only if the head of one standing ‘inside of it be upon the south pole; with that of the spheres of the planets which move from west to east, on the other hand, only on the opposite supposition. |
CAJANUS,^' -a-nus (from the Malay name Catjang), a genus of plants, belonging to the natural order Leguminosce, sub-order Papilionacece. The species yield a kind of pulse, known as pigeon-peas, much used for food by the poor of the West Indies. In Jamaica,, pigeons are usually fed with these seeds ; hence their English.name.
CAJEPUT. (See Melaleuca. )
CALABAR BEA1ST, JcaV-a-har, the seed of Physostigma, venenosum, a twining plant of the natural order Leguminosce, somewhat similar to the kidney bean. It is a very powerful poison, but very small doses of the powder or extract are found to be valuable in teranus, paralysis, and other diseases of the nervous system. When placed on the eyeball, a remarkable: effect of contraction is produced, of which eye-doctors avail themselves.
CALABASH TREE, (See Crescentia.)
CALABASH NUTMEG. (See Mono-
DORA.)
CALADIUM, Ml -ai'-di-um, a genus of plants belonging to the natural order Aracew. The species are mostly natives of South America and the W est Indies, and are frequently cultivated as stove-plants in this country for the sake of their elegant spotted stems and neat leaves. They have the same general appearance as the species of Arum, and resemble them in being all more or less acrid. The sj)ecies O. seguinum is highly poisonous, and when any part is chewed, the tongue swells so much that the power of
speech is lost. On this account, it has received the popular name of dumb-cane. C. sagittifolium, the Brazil cabbage, is cultivated in many parts of the world for its leaves and root-stock, , which, when boiled, are edible. The leaves are preferred, and are said to form a most nutritious and delicate vegetable. The corms of many other species, when cooked, are edible; ,
CALAMANDER-WOOD. (See Bio-
SPYROS.)
CALAMARY, JcaV -a-ma^re, squid, or sleeve fish, a genus of cephalopodous molluskSj the various species of which are distributed all over the world. The body contains an internal shell shaped like a pen, and the mouth is furnished with eight arms. Like the cuttle fish,, they have the power of diffusing a dark-coloured liquid around them in the water. The common, calmary, popularly known as the squid, grows to nearly i£ feet in length, and is of a bluish colour speckled with purple. (See also Cephalopoda.)
CALAMINE, JcaV-a-mine, a carbonate of zinc, found in various parts of America in rhombic prisms and in massive incrusted aggregations. It is an important ore of zinc. (See Zinc. )
C ALAMOTTHA, Ical-a-min' -tha (Gr., Jcalos,, beautiful, mintha, mint), a genus of plants belonging to the natural order Labiatai. Four species are natives of Britain, and are known respectively by the names of mountain-balm, catmint, basil-balm^ and wild basil. The fir st, which> is also termed the common calamint (C. officinalis)^ has aromatic leaves, which are frequently employed by country peoply to make, herb-tea, and as a pectoral medicine.
CALAMITES, TcaV-a-mites (Lat.r calamus,, a reed), fossil stems occurring; abundantly in the; ; coal-measures, where about 40 species have already been discovered* They are hollow- jointed cylinders, with longitudinal furrows, and their flattened condition proves that, they must haver been so soft as to offer little resistance to pressure. Hooker supposes them to be allied to Eerns> or Club-mosses.
CALAMUS, MV -a-mus (Lat., from Gr., Jcalamos, a stalk, stem, or reed), a pen made front a reed, probably the stem of Arundo Donax, used by the ancients. The best were obtained, from Egypt. The stem was softened, dried, and then cut as quill pens are now cut. The reedpen, called Kaldmhy the Arabs, is still commonly employed in Oriental countries. |
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STATISTICAL TABLES.
‘BO UIpIng puv spuno1s Jo onjuA 9 “‘Uor}M) puy prvog Dp
“O88T Ieak OY} OF OI” SUIPSTIVIS CSOT, D ‘“6L8T UI @ “O88T 1oy WMoTyeoupy Jo 1eUo[ssyUIUIOD oy} Jo Yrodoxy MoI y ipdareviteea i idenn es |eammgny RODOL COP a |,07, j $2 OLT fase: |L00r or | 9 x ~ ,AICUTUIOS e[eMOg ToUNLZS |
IS
L864
T.S61
26.W
L861
T.S60
T.S56
3d
42. 7S
T.S59
X.861 L861
Table XXIX.
^ = 3 ex. Propyl formi ate ; x = c.c* Water ; z = c.z. Alcohol, ForniuU 4r(7 - 0,(H xf^/%^^ = C; log £7= T.967-
s.
CaJc
Pound.
lofC
2.E3
T,969
T.50
T.966
1X50
T.962
2L60
T.973
T.%2
IS
cc
T.%7
No. 3]
TERNARY MIXTURES.
Table XXX.
y = 3c.c. Butylformiate ; x = c.c. Water ; « = c.c. Alcohol Formula x i^y - 0.01 j-) 5 /zt = C ; log C - 0.057.
Calc.
Found.
logC.
0.W1
0.W8
Table XXXI.
^ = 3 c.c. Amylformiate ; x = c.c. Water ; « = c.c. Alcohol. Formula x(^y - 0.005 xf^/z^ = C ; log C = T.808.
Calc.
Found.
logC.
T.829
T.820
T.809
T.806
T.807
T.808
T.805
T.808
T.809
T.808
T.813
(T.830)
(T.842)
(T.842)
(T.845) T.811
2IO DR. L. T, MORE, [Vol. III.
ON THE CHANGES IN LENGTH PRODUCED IN IRON WIRES BY MAGNETIZATION.
By Louis Trenchard More.
THIS investigation was undertaken at the suggestion of Professor Rowland, and has for its object the finding of a relation between the change of length produced in iron wires by magnetization, and the intensity of magnetization existing in the wire. It was hoped thus to obtain results that would be comparable, and to avoid certain errors common to all previous work.
Historical.
That magnetizing an iron rod causes it to alter in length was first discussed by Joule ^ in 1847. His attention was called to the phenomenon by a machinist of Manchester, who imagined that the volume of a mass of iron was increased by magnetizing it. Joule, to test the opinion of the machinist, immersed a mass of iron in a closed vessel full of water in which stood a fine capillary tube. When the iron was strongly magnetized, the height of the column of water in the tube remained unaltered, showing that within the limits of accuracy of his apparatus, for the intensity employed, the volume of the iron was unchanged. BidwelP has also investigated this subject and found, on the contrary, that the volume was altered by magnetization. The volume diminishes at first and attains a minimum ; it then increases until with sufficiently intense fields the original size is regained ; after reaching this point the volume continues to increase. As a consequence of this relation, if Joule had used an intensity either greater or less, he probably would have noticed a change in the volume. Joule afterwards, by means of a system of levers, found that the length
1 Joule, Phil. Mag. (3), Vol. XXX., pp. 76, 225.
2 Bidwell, Proc. Roy. Soc, Vol. LVL, p. 94.
No. 3] CHANGES DUE TO MAGNETJZATIOPl. 211
of a rod was increased by the magnetizing force, and gave as a result of his observations the following laws : --
1. When soft iron rods are magnetized, their length is increased and the elongation is approximately proportional to the square of the magnetizing force.
2. Tension applied to the rod diminishes the elongating efifect, and -- " In the case of a bar one foot long and one-quarter inch in diameter, a tensile force of about 6oo pounds caused all the phenomena of changes of length to disappear."
3. "That the elongation is greater, for the same intensity of magnetism, in proportion to the softness of the metal. It is greatest of all in the well annealed iron bars, and least in hardened steel. This circumstance appears to me to favor the hypothesis that the phenomena are produced by the attractions taking place between the magnetized particles of the bar, an hypothesis in perfect accordance with the law which I have pointed out," -- that the elongation was proportional to the square of the intensity of magnetization. |
TannocatFeic Acid ....... 403
Boheic Acid ....... 405
Angelic Acid ....... 406
Benzoic Acid . . . . . . . --
Nitrobenzoic Acid . . . . . . .410
Cuminic Acid . . . . . . . --
Cinnamic Acid . . . . . . .411
Benzilic Acid ' . . . . . . . --
Anisic Acid . . . . . . .412
Nitranisic Acid . . . . . . .413
Anilic Acid . . . . . . . --
Picric Acid ....... 414
Chloropicrin . . . . . . . --
Nitro-bichlorophenic Acid . . . . . .415
Chrysamic Acid . . . . . . . --
Constitution of the Acids Cn Hn 04 . . . . .418
Acetones of the Acids Cn Hn 04 . . . . . --
Sources of the Acids Cn Hn 04 . . . . • --
Formic Acid . . . . . . .419
Acetic Acid ....... 420
Aldehyde ....... 421
Metacetonic Acid . . . . . . .423
Nitrometacetonic Acid . . . . . .425
Butyric Acid ....... 426
Valerianic Acid ....... 428
Decomposition of Valerianic Acid by the Electric Current . . • 429
Fatty Acids in Oil of Cocoa-Nut . . . . .431
Fatty Acids in Castor-Oil ...... 432
(Enanthole ....... 434
Doeglingtrain Oil . . . . . . .437
Acid from Behen-Oil ...... 438
Examination of the Fuel from an ancient lamp . . . . --
Fatty Substance from the Body of a putrified Animal . . .439
Action of Sulphur and Heat upon Fatty Oils . . . . --
Acids of Fir Resin ....... 440
Researches on the Anacardium Fruit . . . . .441
Anacardic Acid . . . . . . .442
Cardole ........ 444
Uric Acid ........ 445
Decomposition of Uric Acid by Ferricyanide of Potassium and Potassa . . 447
Hippuric Acid ....... 450
Amides, Nitriles, Anilides, and Collateral Matters . . . 451
Amides. Phosphamide . . . . . • --
Sulphocarbamide . . . . . • .451
XIV
CONTENTS.
Metacetamide, Acetamide, Valeramide Chlorocarbethamide, Chloracetamide Anisamide .
Cuminamide .
Nitrobenzamide .
Chlorobenzamide .
Phtalamic Acid .... Action of Hydrosulphuric Acid on Hydramides Nitriles ..... Acetronitrile ....
Chloracetonitrile .... Butyronitrile and Valeronitrile Cumonitrile ....
Action of Hydrosulphnric Acid upon Benzonitrile . Anilides . . .
Chlorocyanilide .... Fluosilicanilide .... Oxanilide ..... Oxanilic Acid ....
Oxaluranilide ....
Succinanile, Succinanilic Acid, and Succinanilide Succinanilide ....
Suberanilide and Suberanilic Acid Phtalanile and Phtalanilic Acid Camphoranile and Camphoranilic Acid Carbanilic or Anthranilic Acid Sulphocarbanilide .... Cinnanilide ....
Cumanilide ....
Anisanilide ....
Naphtalidides ....
Carbamide of Naphthalidine Naphthalidine-Sulphocarbamide Organic Bases. Nicotine Nicotine and Protochloride of Platinum .
Quinine .....
Hyposulphate of Quinine
Phosphate of Quinine
Hydrosulphocyanate of Quinine
Hydroferro- and Hydroferricyanate of Quinine
Adulteration of Quinine
Substitute for Quinine
Cinchonine ....
Hydrochlorate of Cinchonine .
Hydrosulphocyanate of Cinchonine Hydroferro- and Hydroferricyanate of Cinchonine Chlorocinchonine and Bromocinchonine .
Quinidine ....
Pseudoquinine .... Morphine ....
Hydrosulphocyanate of Morphine Amount of Morphium present in Opium . Sulphomorphide and Sulphonarcotide Cotarnine ....
Codeine ..... Papaverine ....
Piperine ..... Hydrosulphocyanate of Strychnine Hydrochlorate of Strychnine and Cyanide of Mercury Hydroferrocyanate of Strychnine
Page
CONTENTS.
XV
Page
Chrorostrychnine and Bromostrychnine ..... 484
Phosphate of Brucine . . . . . . --
Hydrosulphocyanate of Brucine ..... 485
Hydroferrocyanate and Hydroferricyanate of Brucine . . . --
Bromobrucine . . . . . . . --
Products of decomposition of Brucine by means of Nitric Acid . . --
Theobromine . . . . . . .488
Caffeine ........ 489
Berberine ........ 490
Harmaline . . . . . . . --
Harmine .*...... 492
Hydrocyanoharmaline . . . . . .494
Nitroharmaline . . . . . . . --
Corydaline ....... 496
Digitaline . . . . . . . --
Gratioline . . . . . . .497
Agrostemmine . . . . . . . --
Organic bases containing Phosphorus . . . . . --
Thialdine ....... 498
Selenaldine ....... 500
Carbothialdine . . . . . . . -- |
. 5 of NATURAL PHILOSOPHY. 37 6. By exact Calculation upon these Observations, we 6 Hee Sacb find that the greatest Distance of the Center of the Earth lf R from the Moon is * somewhat more than Sixty- six Semi- Earth and diameters of the Earth, and its least Di about Fitty- the Moon is one; and that the Moon's true Diameter is pretty near a the ove 2 fourth Part of that ofthe Earth, whence we conclude; that compared the Earth is Tie ane Ha ve Times as big as the Moon. g 2 7. The * the higher it is above -- Horizon, the less is its Par bra lar; that of the Sun is not sensible, unless when it is in . the Horizon, that is, in the Circle which terminates - our i, and what Sight: And when the Sun is in the Horixom, it is very diffi- -- cult to find its Parallax. Upon the most exact Calcu- -- Ang
lation, its st Distance from the Earth is found to 4ng/e 43D be 2 about Fifteen hundred and fifty Semi diameters of 7 evides
the Earth, and its least Distance about Fourteen to any on
and forty-six Semi-diameters. The Diameter of the ee, Sun is also found to be about fifteen Semi- diameters of the Earth; 1
Four hundred and ow times as as _ "___ big
S a A
-- are pretty well agreed 2 the Moon's nce from the
: Its -- 2 4 cording to Se 4 mo 4855 of the 2 according to cn, and one Third nd acndin wd thr
-nine
2. About Fiftees hundred and fif- the ty, &e.) As it is very difficult and troubl to find the Sun's Pa-
rallax, fo its Distance from the Earth is not so well agreed upon,
The Sun's mean Distance is by sorne -- 749 Diameters of the
ers 10000 Or 12000» Et b by e exactest Observations of the latest Astronomers, but - 5000 3 and its true Diameter to che Diameter of the Earth, as 10000 to 208, Whence it Fob wir that the Sun is 1 times bigger 2
According to the best Astrongmers, che true Bigness of the Pla nets, and their "Distance from the Sun are as tollows, * --
een
Sture, Ses the Neves on 4-0 wo
Art. „ Cu Pare: | OY
FNofaorristsrin Part H. n flowery wt 5 P CHAP. XIII. 6 | Of the, Phenomena of Mercury aud Venus. 3 4 HE Planet Mercury * is v anale ad they only who . A find it out ey che Rules of 7 -- can know
| C
it n it from the fixed Stars; it is so bright, 2s to be easisy taken for a fixed Sta. a. hee 2. Next tò the Sun and Moon, the Planet Venus is the eus Venus. most remarkable, because it appears so large; all Counrag 12 -- almost, know it by the Name of the Shep- 7 S a S=Star. e | 111 8.
Of the as. 3. By comparing Mercury and Venus with the fixed Stars 2229 N -- Method, in order to know pl. 7 4 Ve. Whit the Position of cheir Orbits is, with regard to the BY
hn. 9 find; that each of these Planets moves from
West to East in Circles, which cut the Ecliptick in two
opposite Points, and deviate from it to a determinate 25
Distance, viz. that of Mercury, fix Degrees and sixteen ,
Minuter, and that of Venur, three Degrees and thirty fl fs Minutes. 3 1 * | W Nen Jof the pe- | 4 Mercury and Venus, take up about a Vear in moving
n., a -their Orbits; and though seem sometimes 0
bens, to move faster, the) recompense it by moving flower |
At Other Times, without observing any Rule; yet how- {
ever, they perform their Revolutions in such a manner, ww
as always to pass through their Orbits in a Lear; fo that 1
we map affirm in general, that they make ong Revolution | *®
| eee TPO be
5. Of the Di- 7. Mercur) enus appear always very 15
8 of Mercury is never above Twenty-ei -- -- Venus Fs
Mercury #92 never above Forty- eight Degrees distant either to the East i tf
* has, Or est. * | : ; ” cer,
7 8 Arid bow 6. When Mercury and nuf are the most Rast that they Mo
song "Tims Fun be, of the Sun; that is, when Mercury is Jn 7 -- eight Degrees, arid Venus Forty- eight East of it; We ob- bow these Distan- serve, that. they then move slowly towards the West, 275 tes. till they are got as fag West of the Sun as they were be- |
■Iri^liihithiifly copadtiitcA wd {vpnridFd witl^ b^io^ HwiiMifiTiglH nrnJiam matt wr, 1111111111 hriffjnr iwnfii ■■r^lwii[^^| itfpplied with « dtgeae of iodividiw}^ aepaibBitj, sniteiji to iti oipiioiiy far gra^yiag' ily denrasr frotti the gtwt fionrae df life, wldi^ tliuB dweUittg Ifl Kglity cnsatct nqrriadv of itpftk^iol dbrivattve' animatiaD^ oaob for a •time' d^^ighting in ita bebg^ thin tnmbbiiig^' aoootdin^to the laws of aldmki movameiit^ to be flttcoceded by -aoodier and atootber Uka itfldf ?■
'IBm opinion iN^^ld exfdain wby ainmal ibtma abbuld bc^ at ife find they aroi ^ismatanlly'tHidtng towards a vaotPt pou fect ofganio deTebpment';- far ^rere they animated ukrtbb way» we can only believe that the organiiiiig jaflaeDne-wbidi abtuaties- them, must be-, cooatantly tending to raiae than in file scale of beingSi as far as the physical dfciimatMicBS avound them admit. Wby they ebould possess the fcnna and instincts which they do possess, and not others, inll appear' by-and-by, after we have bestowed some puns on the consideration of Man. But what shall we say of this istrange Being P It is evident that He is not animated in this way. His moral and natural history, every circumstance respecting man, single him out from among all animals as a peculiar species, and prove him to be either a microcoem, or else a mystery. Now, it is to be remarked, of all the pro^ oeedings of the Supreme Being relating to the present universe, that nothing is done of a sudden and in full development at once ; that something new is never violently attached to some other thing quite different from it. Every thing b brought to pass by gentle transitions from one state to another, after the manner of ordinary evolutions. The calm ocean is not on a sudden raised into a storm, at the moment when the wind rises. The brightness of day is not sud-
OF FINITE SnNM. 589 |
its upper end L communicates with the delivery pipe D. In L is suspended a bowl-shaped casting E, provided at the bottom with a stuffing box G for the shaft, which is supported by a collar bearing at K. The water which passes from the suction pipe C into the casing is flung outward by the wheel, and flows along the curved surfaces of H into the delivery pipe, where it rises to a height corresponding to its velocity and hydraulic pressure. The upper part of the casing H is provided on the inside with a number of guide blades /, which are given a gradual curvature, so as to guide the water, which has received a rotary motion from the wheel, without shock into the radial direction, and thus prevent the formation of eddies and consequent loss of efficiency, which otherwise would occur. In some instances guide blades have been applied, as in turbines, to lead the water into the wheel, but such is not the case in the majority of centrifugal pumps ; neither are, as a rule, such guides employed for the discharge in the horizontal types, inasmuch as the latter usually have a casing of such a form that it may be regarded as a single guide blade.
In centrifugal pumps with a vertical shaft the foot valve may be dispensed with, provided the wheel is placed below the lower water-level. It must be noted, however, that for great lifts difficulties may be encountered in the erection of the long shaft and in retaining it in its vertical position, particularly as experience shows that the ground below the suction pipe is considerably loosened by the violent flow of water to the pump when the latter is in vigorous operation.
We may discuss the action of a centrifugal wheel on the water in a manner similar to that employed in tracing the. effect of the driving water on the floats of turbines (see vol. on Hydraulics). For this purpose let AB (Fig. 176) be a blade which makes, with the inner circle of radius r: and the outer circle of radius r2, the angles a and 0 respectively. Let us now assume the ordinary case that water is led to the inner circle without guide blades, that is, in a radial direction, and let us represent the absolute entrance velocity AE of the water by vlt and the circumferential velocity AF of the inner circle A by uv Then, in order that a shock may be prevented, the first element of the blade at A must have a velocity in the direction AL equal to the initial velocity of the water relatively
MECHANICS OF PUMPING MACHINERY
CHAP.
to the rotating wheel. This condition is expressed by the equation
In consequence of the initial velocity vl of the water and the simultaneous rotation of the wheel, a particle of water entering at A will traverse an absolute path represented, say, by the curve AD, which cuts the outer circumference at the angle KDO = S.
Fig. 176.
Let v2 represent the absolute velocity with which the water leaves the wheel in the direction DK, and u% = DO = BH the tangential velocity of the wheel at the outer circumference ; then the relative velocity c2 with which the water moves along the last element B of the blade AB will be the resultant BJ of the absolute velocity BG = v2t and the velocity GJ = HB = -- uz equal and opposite to that of the wheel. The triangle GBJ therefore gives the equation
c22 = vf + u* - 2v2u2 cos 8 . • . - . (2)
ROTARY PU
ing me wheel $1, which may be repre-
in like
In addition to its velocity vl the at A has a certain hydraulic pressu
sented by a water column of the
-- may represent the hydraulic pressure of the water leaving
the wheel at B with the absolute velocity v%. These pressures may be easily determined. For, let b be the height of the water barometer, ^ the height of suction estimated from the lower water-level up to the axis C, h.2 the height of delivery measured from C to the upper water-level O, and let £\ and £2 be the heads corresponding to the resistances to motion in the suction and delivery pipes respectively. As may be seen from the figure, we then have |
Tlie peculiarity of Duhamel's process consists Sn the «mp1oymcnt of the pieces of iron M m, and in the use of bundles of sm.all bars, wliich •n more efficacious than two single ones of the same size. In proporalao aa tlie steel bars acquire magnetism, the connecting pieces |iarticipate in the acquisition of a similar power, and serve to retain it in the bars themselves ; just as tlie Electricity which is imparted to the oer coating of a Leyden jar, is retained by tho reciprocal influence of e inducted, and contrary Electricity of the outer coating. The magisnt of the bars is retained by a similar influence, and greater facility Uius afforded to increase its amount, by the subsequent additions it U
X 2
MAG^mSM.
receivinf^ from the action of the mftgneisi aa tlioy pan mkng tlio surfaco.
(527) Alwul the same time tliat Duhaniel was occupied with Uii* subject, Mr. Miclioll, of Cambridge, and Mr. Cnnttm, were aoparmtoly engaged in the same inquiry. Mr. Michcll published his method in 17o0» to which he gave the name of nnthotl h^ donhU touch, H&viofr joined togetlier, at the diatauceof a quarter of an inch, two bundlpc of strongly ningnclii»ed bars.
Fi«. 188,
A A\ Fig. 188, their opposite poles, N St being together, he placed five
or more equal steel bars, jj* b' ;» /*' r ■
B If B' B" B\ in tlie sarao straight line, and resting the extremity of the bundle of magnets, -1 A\ upon the middle of the central bar, //, h9 mored them hachtariU and /ortcards throughout the whole length of the lino of bars, repeating the operation on each side of the bara, till the greatest possible effect was produced. By this method Mr. Michell found that the middle steel bars, B B By acquired a very high degrto of magnetic virtue, and greater than the outer bars, B* B' ; but by placing these bst bars in the middle of the series, and rq>eatitig tli« operation, they acquired the same power a$ the rest. Mr. Michelt states that two magnets will, by his process of double touch, commitnicate as strong a magnetic virtue to % steel bar, aa a single magnet of five times the strength, when used in the proc^?39 of single touch. Tlio bars A j4'act with the sum of their powers in developing magnetiau ■11 parts of the line of the bara between them, and with the diffi of ihcir powers in all parts of tho line beyond them. Thoextenud act the same part in this process aa tho two pieces of soft iron ia method of Duhamel.
(528) In the year 1831 Mr, Canton published his process, which b» regarded us sii[>crior to the preceding ones. He placed the bars a« In Dnhamers method, joined by pieces of soft iron. lie theu applied MichcU's method of double touch, and afterwards he aeparated the two bundles of magnets, A A'; and having inclined them to each otitcr, at in Duhamol's method, he made them rub upon the bar from the middio to its citremitics. The peculiarity of Canton's method is tho uniun uf theae two processes ; but Coulomb and others are of opintuo that the hitter part of the proceaa is the only effectual one.
(.'>2!)) In order to nmko artificial magnets, without tho aid cttlier of natnral loadstones or artilieial magncta, Mr. Canton gives the following detailed proccaa : --
He takoa six bars of aoft, and six of hard itecl ; the former bctog umallrr than th« latter. The bars of tofi. cteel slmuld be thrtre indMV
LECTTRK Vn. |
It may fairly be questioned whether there be a subject connected with medicine upon which opinions are so various and so numerous as upon that of epidemics. We read of subtle poisons, held, in solution by the atmosphere; of noxious effluvia, arising from marshes, or from decaying animal and vegetable substances ; but these supposed poisonous particles have never been detected by our most able chemists. Even admitting that matter, undergoing decomposition, may, in the first instance, affect an individual, it remains to be explained in what manner the propagation of the disease from one individual to another, or to a number of others, can be effi^cted. Whatever disagreement of opinion, however, may exist as to the specific cause of epidemics, the idea that it exists in tlie atmosphere is generally entertained. Now, it is material that we should bear in mind that the composition of the air is not only constant in the same place, but in all regions, and in
COMPOSITION OF THE ATMOSPHERE. 329
every latitude. Whether collected at the summit of Mont Blanc^ or Chimborazo^ or in the lowest valleys^ its elements are invariably the same^ and in the same relative proportion. Berthellot has examined the air of £gypt^ and he found it to be similar to that of France. Gay-Lussac brought air from an altitude of 21^735 feet above the earth, and found its composition the same as that collected at a short distance from its surface. Hence the idea that the healthiness of the air^ at different times, and in different places, depends upon the relative quantity of oxygen gas> has been exploded. Even in the miasmata of marshes, and the effluvia of infected places, there is no deficiency of oxygen^ so that their noxious qualities must be owing to some principle of too subtle a nature to be detected by chemical means. Nay, more, in the infectious atmosphere of an hospital, the odour of which was almost intolerable^ Seguin could not discover any appreciable deficiency of oxygen, or detect any other peculiarity of composition. Perhaps some of our readers may not be aware how very small a proportion of any foreign ingredient can be detected ; if so^ the following experiments will satisfy them upon this point : -- A. single grain of iron, dissolved in nitrohydrochloric acid, commonly called aqua regia, and mixed with three 3,137 pints of water, will be diffused through the whole mass; by means of the ferrocyanuret of potassium, which strikes a uniform blue tint, some portion of iron may be detected in every part of the liquid. This experiment proves the giain of iron to have been divided into rather more than
330 COMPOSITION OF THE ATMOSPHERE.
twenty-four millions of parts ; and if the same portion of iron were still further diluted^ its diffusion through ihe whole liquid might be proved by concentrating any portion of it by evaporation, and detecting the metal by its appropriate tests. Again^ starch is sq delicate a test of the presence of iodine, that^ according to Stromeyer^ a liquid containing l-450^000thof its weight of iodine^ receives a blue tinge from a solution of starch. These facts are mentioned to show how very greatly diluted those poisons must be >vhich the air is supposed to hold in solution^ when they thus baffle the endeavours of the most scientifip chemists to detect them. And we can scarcely be so credulous as to conceive that existing as they must (if, indeed^ they exist at all except in imagination)^ in a state so diluted, and consequently so very widely diffused, they could be capable of producing the powerful^ and, in many instances^ the sudden effects which have been ascribed to them. We bave^ therefore, perhaps sufficient grounds to justify us in rejecting the notion of a ^^ poisoned atmosphere" being the cause of epidemics^ as unphilosophical, inasmu(^h as it is devoid of even the shadow of proof.
CHAPTER X.
Epidemics attributable to the Electrical State of the Atmosphere. -- Spasmodic Cholera ^ ^c.
The salutary art |
But for a stratum external to the attracted jiarticlc we ol)tain bv Art. 182.
r=47rpa«r/ +47roa ---7 -- ii+ -f . ,. -- l ■ -r ... \da .
and therefore for all the strata external to the par tick'
and conseciuentlv for the whole body
dV From this the ^ittiMctioiK or - - , i- rn-«il\ oht^nncd.
(I }'
DYNAMICS.
CHAPTER I.
DEFINITIONS. LAWS OP MOTION.
187- In this part of our Work we are engaged with the laws which regulate the motion of bodies. We shall proceed therefore to explain the means we use for measuring the motion of a body algebraically.
The position of a body in space, considering the body as a material particle, is determined at any instant by its distances from three fixed planes at right angles to each other: these distances are called the dh-ordi nates of the particle; and the position of a rigid body in space is determined at any instant by the co-ordinates of a given point of the body and the angles which three fixed lines in the body make with three fixed lines in space.
If the body be in motion the co-ordinates will be continually changing in magnitude : and one of the chief objects of the Science of Dynamics is to find the analytical relation between each co-ordinate and the time of motion.
188. We shall pause, however, a little to make a few remarks which cannot be too carefully remembered.
All our ideas of the magnitude of quantities (such as space, time, and so on) are ideas of comparative and not absolute magnitude : for a quantity may be great when compared with one standard, and small when compared with another. In consequence of this it is necessary, in order to avoid ambiguity, to choose for quantities of the same kind a certain standard to
t SE. t>siTi uv (EfooMN.. I's-irs or- mkashuk. I77
.Imli tlh'V iiMV hr n'f.Tic.). 'I'his standard i> called tlio «/n/ iif the-f quamitii-. 'I'liu'* mo speak of the unit of time, ad the unit of «]iiU'c ; !)_v wliicli wc mean the duration of lime and the extent nf sjwtv wliich wo choose as standards to whidi all otiicr quiiiititit's of iIu'm' npirics ari' !o he severally referred.
It is by this means that qiianliiii - an' mado llu' -ubjecls of numerical cakulalion. For inslaiu.'. nhi'ii ne say lii^il a Imdy (Ifst'rihes a space '■ in a tiiin- /. Mr 111. aiK ihat 1 and / rcprewnt the ratios which tlic ■-]ia..- dc-i rilnii and llir liiiii' of dc- -cribilig it bear to their i-i'f.iir,-ii. , miil- . .uid >.i of all other quantities. We f<irliear chunM it generally happens, a.s .ir -halt sia\
rinsing the=c remark- i\i' Mill nbtsanie calenlatioa \v,- nm-t liaM' only of (he same kind, yet in dillVreiil retain the same unit, mi liniu a^ «i is eliosen in each cnlcTilalion 'I' mipht take the lengtli of iln. mv:\n we shnidd refer all jiortion- I'f tinu lalion wc nn'ght take a year a^ ihe now to the consideration of ihe meal of a body,
189. Vfi/orif;, \^ a term iim-.I quickness or slowness with whieli a body lie uniform or variable.
190. Cnifurm Velof-Uij. Velneity is said to iic uniform when the body passes through equal spaces in equa! times.
It appears, then, that the magnitude of the velocity of a body moving uniformly depends conjointly upon the space described and the lime of describinr; the space; and is greater or less exactly in the proportion in which the space described in any given time is greater or less, and the time of describing any given space is less or greater.
Consequently when bodies move with different uniform velocities, these velocities are in the proportion of the ratios which the spaces described in any times bsar respectivelv itj the times of dcscribins: them.
I .IM<N
t „li,v l)..,;,.l.,.
f. Itliit
j'iliiJ.' IKfoiv ili.niKli in tin' 'd of iiiiautities
In.lMli..
s we need imt lind uhal unit
t <.f tin
eidculalion wu imit to which anulhcrcalcue. We return
if IIH.,TM
ring the motioii
ill.li.'.ltl
llie degree of \ eloeity may
1^8 "DYNAMICS. |
CA'MES, or CA'MET. See ARGENTUM.
CA'MINGA. See CANELLA ALBA.
CAMI'NUS. A furnace and its chimney. In Ru- landus it signifies a bell.
CAMI'SIA FCETUS (from the Arabic term kamisa/i, an under garment). See CHORIUM.
CA'MMARUS. The LOBSTER, or CRAY FISH ; so named from the shape of its shell. See CANCER FLUVIATILIS.
CA'MMORUM, (quia homines KXX.U >*.*?<* perimat,) NIGHTSHADE; because if eaten it destroys in a deplorable manner. See CAMAHUM.
C A "SI
C A 31
CAMOTES I'XDICA. See BATTATAS HISPA-
JCT
\MO'MILLA, corrupted from CHAM.EMELUM, •which see.
( \MPA'XA. A BELL; so called becavsc Paulinus, the bishop of Nola in Campania, first used bells for religious purposes. In chemistry it is a receptacle for the gas of sulphur, where it is concentrated and col- ••(! together into a fluid, the oltitm fianam, which is only the modern sulphuric acid. \ '• Mi'A XUL^E, (a dim. of Cam/icnaJ. See CER-
V1CARIA.
CA'MPE, (from xxft.-r~a, to bend). A flexure or bending. It is also used for the ham, because it is the part usually bent; and for a joint, or an articulation.
CAMPECHE'NSE LI'GNUM ; brought from the bay of Campeachy in America. LOGV.-OOD; also called jfcacia Zeylanica, lignum Camfiescanum, sajifian lignum, tfiam fiangam, lignum Camfiechianum, Indicum montanitm lignum, lignum t'mctile Cam/itch. CAM- PEACHY, BRASIL, or JAMAICA WOOD.
It is the Kjod of a prickley pod bearing tree, a native of Campeachy island. It is brought to Europe in large compact logs of a red colour. Its fruit resemble cloves in their quality. It is the htzmatoxylon camfiechianum Lin. Sp. Plant. 549. Nat. order Ivmejitace<e. IL-EMATo'xYLO.v, (from «lujt, 6lood, and |t-Aa»,
!io called erythrvxylon.
This wood, of which the tree is a native of Honduras, is chiefly brought for the dyers, but used medicinally as an astringent or corroborant. • It is peculiarly efficacious in diarrhoeas, and in the last stages of dysentery. When the obstructing causes are removed it restrains the discharge, without contracting the fibres like astringents : it sheaths acrimony, and its astringent taste is combined with a sweetish mucilaginous one; strengthens the bowels, and perhaps the general habit. It is an agreeable medicine, being free from any thing disgusting to the taste, and almost void of smell.
The London college direct a pound of the shavings of logwood to be boiled in a gallon of distilled water to one half; this must be repeated four times. The fluids must be mixed, strained, and boiled to a proper consistence. The shavings are ordered to prevent it from being mixed with the Jamaica, or other cheaper woods; h might be the case if bought in powder. The dose is from 3 i. to 5 ss. repeated according to the urgency of the symptoms.
Rectified spirit of wine takes up more from this -icr; therefore it is better to digest its powder in as much spirit as will cover it three or four ;s' breadth above its surface, then boil the residuum in water, as directed above. The watery menare first evaporated to the consistence of honey, then the spirituous extract, formed by drawing off" the spirit, is mixed with it.
The decoction of logwood is made by boiling three
.powdered log-awd in four pints of water to
two, at the end of which two drachms of cinnamon are
added, and boiled together a few minutes. When cool
the decoction is strained.
Both the extract and decoction are agreeable, mild, and safe, when stronger astringents are less advisable; and may be used with equal safety whether a fever
attends or not. These preparations make the stoolb and urine appear like blood. The decoction may be taken in the quantity of four ounces three or four times a day.
The preparations of this wood are chiefly held in esteem for their astringency, and may be given safely influxes and at the 'close of dysentery ; but i . ginning they are hurtful. Cullen. |
Opaque substances are those which permit no light to pass through them ; as metals, wood, &c.
9. What is a ray of light ?
A ray of light is a single line of light proceeding from a luminous body.
10. When are rays of light said to diverge?
Rays of light are said to diverge when they separate more widely, as they proceed from a luminous body. • The figure represents the rays of light diverging as they proceed from the luminous body, from F to D.
11. When are rays of light said to converge?
Rays of light are called converging when they sipproach each other.
80 OPTICS.
12. What is the point called towards which they converge? The point at which converging rays
meet is called the focus. The figure represents converging rays of light, of which the point F is the focus.
13. What is a beam of light ? A beam of light consists of many
rays running in parallel lines. The figure represents a beam of light.
14. What is a pencil of rays?
A pencil of rays is a collection of diverging or converging rays.
15. What is a medium ?
A medium is any substance, solid or fluid, through which light can pass ; as water, glass, air, &c.
16. In what manner do rays of light issue from terrestrial bodies? The rays of light which issue from terrestrial bodies, continually diverge, until they meet with a refracting substance.
17. In what kind of lines do the rays of light proceed from the sun?
The rays of the sun diverge so little, on account of the immense distance of that luminary, that they are considered parallel.
18. In what way is light projected forward from any luminous body ?
Light, proceeding from a luminous body, is projected forward in straight lines in every possible direction.
OPTICS.
19. How fast does liijht move ?
Light moves with a rapidity but little short of 200,000 miles in a second of time.
20. From what point of a luminous body does light radiate ? Every point of a luminous body is a centre, from which
light radiates in every direction.
21. Do the rays of light cross each other?
Rays of light proceeding from different bodies, cross each other without interfering.
83 OF SflADOWS, AND REFLECTED LIGHT.
Lesson IXV.
OF SHADOWS, AND REFLECTED LIGHT.
1. What is a shadow ?
A shadow is the darkness produced by the intervention of an opaque body, which prevents the rays of light from reaching an object behind the opaque body.
2. Wliat effect is produced on the shadow of an opaque body, when the luminous body is larger than the opaque one ?
When a luminous body is larger than an opaque body, the shadow of the opaque body will gradually diminish in size till it terminates in a point.
3. What will be the form of the shadow of a spherical body, when the luminous body is larger than the opaque body ?
The form of the shadow of a spherical body, when the luminous body is larger than the opaque body, will be that of a cone. In the figure, A represents the sun, and B the moon. The
sun, being much larger than the moon, causes it to cast a convergmg shadow, which terminates at E.
4. When the luminous body is the smaller, how will the shadow be affected ?
When the luminous body is smaller than the opaque body,
OF SHADOWS, AND REFLECTED LIGHT.
the shadow of the opaque body gradually increases in size with the distance, without hmit. In the figure, the shadow of the object. A, increases in size at the different distances, B, C, D, E, or, in other words, it constantly diverges.
5. When several luminous bodies shine upon the same object, which of them will produce a shadow ?
When several luminous bodies shine upon the same objecit, each one will produce a shadow. The figure represents a ball, A, illuminated by the three candles, B, C, and D. The light B produces the shadow 6, the light
C, the shadow c, and the light
D, the shadow d ; but as the light from each of the candles shines upon all the shadows, except its own, the shadows will be faint.
6. \Vlien is liccht said to be reflected ? |
" Blessed are the poor in spirit ; Blessed are the meek ; Blessed are they which do hunger and thirst after righteousness ; Blessed are the merciful ; Blessed are the pure in heart ; Blessed are the peacemakers." We open to the last chapter of the sacred volume and we read : " Blessed are they that do his commandments," -- or it is just as appropriate if we quote from the Revised Version : " Blessed are they that wash their robes," -- " that they may have right to the tree of life, and may enter in through the gates into the city." It is a joy simply to think of such a man as having lived among us for a prolonged generation ; through his youth and manhood and age, a rounded life, closing at length as " a shock of corn cometh in in his season."
Whence came this strong, well-established Christian character ? What were the roots of this widespreading, symmetrical, fruit-bearing, evergreen tree?
Our thoughts instantly go back to his childhood and youth in Fitchburg; and some of us do not forget that the revered pastor of the church, of which his parents were members, was that sturdy champion of the faith, and that man of far-seeing vision, as he looked out upon the wants of a perishing world, Rev. Samuel Worcester. We remember
ALVAN SIMONDS. 53
that the record of that pastor and church constitutes one of the most important chapters of that significant volume of New England ecclesiastical history which made the early years of this century so momentous, and that into this history our friend was born only five years after that pastor, who still lived on in his influence in Fitchburg, had been transferred to that second throne of his power, the Tabernacle Church of Salem, where five years later were to be publicly set apart the first representatives of this Western Continent who should bear the tidings of salvation to the heathen world.
Two powerful influences thus entered into the training of the character of the boy and the youth, probably unconsciously to himself, which developed rapidly and impressed themselves permanently upon his young manhood, one emphasizing the fundamentals of the Christian faith, and the other the breadth of the Christian work. When, therefore, he came to Boston at the age of sixteen, during that great revival year of 1823, when Park-street Church and the few churches which sympathized with it were at " white heat," it is not strange that the next ten years, -- a period unequaled for its intensity of evangelistic and missionary zeal, at just this centre of power, by any other period of the same duration in the history of our city; a period during which this youthful disciple avowed himself a Christian believer, and immediately took hold of Christian work, -- it is not strange that the development of those ten years
54 MEMORIAL OF
made the man with all those sterling Christian virtues which commanded the respect of old and young for the fifty years which were to follow. |
Edison's Motograph Receiver. -- A most peculiar; and original (though unpractical) form of receiver is that invented by Mr. Edison, in which no magnet is used, but in which the action is based upon the fact, discovered by himself, that when a piece of paper moistened with certain chemicals has an electric current passed through it the action of the current renders the surface of the paper almost frictionless, and that this effect ceases immediately as soon as the current
THE TELEPHONE. IS7
In the receiver embodying this principle, and represented by Fig. 108, the brass shaft, s, which cin be revolved by turning the little crank, K, has secured upon it a moist cylinder of chalk, C. Upon this presses a brass strip, T, tipped with palladium, which is rigidly secured to the
diaphragm lying in the plane of the paper. The brass strip, T, is pressed against the chalk cylinder by the rubber cylinder, R, the degree of pressure being regulated by the set-screw, M. The connections are as shown in the figure.
When ready to receive, the cylinder is made to re-
1 58 ELECTRICITY IN THEORY AND PRACTICE.
volve by turning the crank, K, in such a direction that the
friction of ,the cylinder will pull the brass strip, T, away from the diaphragm, thus drawing the diaphragm in this direction. This will continue as long as no current is passing ; but as soon .is a current does pass the friction between the palladium and the surface will cease, and the diaphragm will instantly revert to its normal position, from which it will be instantly drawn again as soon as the current ceases. In this way the diaphragm is madeto vibrate in accord with the diaphragm of the tran» mitter.
Induction Transmitters. -- In using transmitters in* which the resistance of the circuit is varied by varying' the resistance within the instrument, it is clear that the current will be varied to a considerable extent when the ratio of the variation in resistance to the resistance of the whole circuit is great. It is also clear that this can be the case only when the resistance of the line is small ; for if we have a long line with high resistance, the proportional amount by which this resistance will be varied by the necessarily slight alterations in the resistance of the transmitter will be too small to exercise any appreciable influence upon the strength of the current. To enable these instruments to be used successfully on long lines it is customary in practice to get over the difficulty by having the circuit of the battery and transmitter very short, terminating, in fact, in the primary wire of an induction-coil of which the secondary wire is in the main circuit. The varying currents sent through the primary wire when the transmitter is used induce alternating currents in the secondary coil. These currents have a sufficiently high electro-motive force to overcome the resistance of a long circuit, the degree of electro-motive forq ~ depending, of course, upon the amount of variation in t primary currents and the length of the wire in the secod dary coil.
THE TELEPHONE.
The Microplione.-- The action of this instrument is very similar in some respects to that of Edison's transmitter, and many modifications of it are used in telephony. In its simplest form the microphone consists merely of two conductors in loose contact, forming' part of an electric circuit, the current passing across the point of contact from one conductor to the other. Carbon is found to be the best material from which to make these conductors, though very good results can be obtained by using some other materials, notably platinum. |
SmA a mmmm h to bne «■£» ffwwi i iui ex moooo la » boiiiMi^l pImk; and if an bofin ol a fcoag^Moa aataxa ata icaaored fian HiS vidaiif , H will, after a few iim ilhtir--, lake «p a poritioc aeaiiy mottli a^amtk; sad. if it W &taibed from tkis poaitiott, and plaoed ia uy aAn^ H win DOi lOBMB tboa ; bat aa aMnaailisat Ebcrty iOD>oT«, ii win naoae tta igniei powtiwi. li wiU abo poaiOB the pow of Mmoakatia^ raagnetioB to haid alerl |iiiiBiiiaiaify, and to ooA trai ^■pwwri/y, the degree of stra^tb, of ccrazae, depeaidiDf( on its o«a power ; aad with leapett to the aleel, on the tima which it ia -- -- f^***^ If two angaeiued ban be poaaed aod pfaaed ia dUfci e ut poHtaBaa i^ ^■BliBg cadi other, it wiQ be fooad that m aocae ciaei thej Appear to ^nltraelad towards each other ; wfaOe ia othera, they i-- t'*'*^ a «a- ^Bl iqmUoo. Thiii, iMwerer, does not happea captiaoaa^ ; the tn ^Mh poloa aod the two aoath poles intaiiably repd each other ; b«i Hi Botth pole of one magaet always attracts, and is of cooiao attxadel ^tthe aoath pole of the other.*
^R[489) In Older to oQsnunMate nagutiBB frocD a aatoial or aiti6cU Vhgnet, to oamagnetized tno or atee!, it ia aot Deoeawy that the tw^^ bodies should be in contact. The eommnaicatxon ia effooted as pedectl|^H thoogfa more Geebly, when die bo&a aie aepamt«d by space. Thus in F^. ITS, if the north poU of Fi«. 172.
an artificial ateel magnet J, ia c jv" i • * • •
placed near the extremity S^ 1 I I a
of a jneca of soft iron ^, the -* * c />
and 9^ will instantly acquire the propctties of a «ouM pole, aad the Op- poaite end n^ those of a north pole. The oppoaiio poke would haw been produced at n and «, if the aouth polo f, of the magDet jI, had been placed near the iron B,
In Hko manner, the iron B^ though only temporarily magoetic, lender another piece of iron C, and this again, another piece D^ porarily magnetic, north and south poles being prodtaied at ; and »', /.
(500) Here wo cannot fikil to obeerre a pointed analogy between phenomena of magnetic attraction and repulsion, and thoee of city. In both there exists the same character of donUe ageaeka opposite kind, capable, when separate, of acting with groat eneryry, and being) when combined together, perfectly neutralized, and exhibiting sagns of activity. As there are two electrical, ao thoro are alio t SMgoetifl powers; and both seta of phenomena aia gorcmod by aame ch&ractorufitic Uws. So alao in the last exporiment, the tisni inherent in B, C, i>, is laid to be inJtic^i by the pfteeace of real magnet A ; and the phenomena are exaotly analagous to tho * ArtiflcUl magtwU luve b«en coavtmctM b) ndaebk^ ut v^^wiW tlio atagavUc oiJtIf, and forming U into \*i% *\tt
ibaa
reealM
Eleel^H Backa JB
WkJicJCL
LECTVnB V7I.
lotucatioD of Electricity to unelectrified bodies hy induction, tlic posi-
ive state inducing tbo negative, and the negative the positive, in tUo
ports of a conductor placed in a state of insulation, near an electrified body.
(501) A simple experiment will satisfactorily show that soft iron po oooQBco magnetic properties, while it remains in the vicinity of a xungoet. Let A, Fig. 173, be a magnet, and K Fig. 173. a key, held either horizontally near one of [ its pules, or near itij lower edge. Then if ^ another light piece of iron, such as a small nail, be applied to the other end of the key, tbc nail will hang from the key, and vrill continue to do so while the magnet is slowly
^^|rithdrawn ; but wliou it has been removed beyond a certain distance,
^Hbe nail will drop from the key, becauso the m.agneti:im induced on the
^^Ley becomes at that diitancc too weak to support the weight of the
Baail, That this is the real cause of its falling off, may be proved, by
taking a still lighter fragment of iron, such as a piece of very slender
wire, and applying it to the key. The magnetism of the key will still
be sufficiently strong to support the wire, though it cannot the nail ; |
Btuuromcnt of complicated bodies. It is pomible thnt if
bis mind had not been e:xerci»i>.d at the time about the
>dtlt«nitioD of the royal crown, it would not have been
I ltd toaaytbing by the ovcrflowin;^ of his bnth, but the
I Mpuity to receive a suggestion of that kind is, I believe,
iQfocity exclusively masculine. A woman would have
, Mittd th« ovorRowing, but die would ha\*« noticed it
vdy as a cause of disorder or inconvenience.'
'Tliis abceooe of the investigating and diecovoriug Itsdeacies in women is confirmed by the extreme rarity <f iBvmtions due to women, cvcu in the things which most ■Blerett and concern tliem. The stooking^hmio aud ^wing* techine are the two inventions which would moat natuftltf have been hit upon by women, for people are *hually inventive alx>ut tJie things whicli relieve themlivt« of labour, or which incrtmse their own possibilities if pmductioD ; and yet. the stoeklug-hioiu and the nevring- Bichine are both of them masculine ideas carried out to [CKtical efficiency by miiscniine energy uud perHcverouce. So I believe that all the inipravements iu pianos are due Wmen. though women have used pianos much more than fta lave u^ed them.' '
■ nunorloa, tnteltmlnal Ufe, p. 313 H My.
rEtcaO!CAL PBKPAIIATIOit tOR OSSBAItCtt'
Much more roroarkalile tbim tlic deficiency of itcientil inquiry tii woin^n is thi; fact that the chief fouotainB new jK-ientific knowledge have not been at our old oniTersitip!>. One would nutiirally tiuppo«e, aiu) might reftsooaU^ expect, that the great sources of such truth would Iw «t those pkcps wliiTi? (ihiitidanoe "f fumis an- provided 'to proinole study,' and where there exists the (juietude of great educational inrtitutions ; but such has not hevn the caKC, till? diiicovcry of tlie truths nf flod in nature baa ootj been most encouraged there, and the great bulk of ori- j ginal invcutigation in pliyitics and clieiiuxt ry ha;^ not '■ made at those placea. I have been informed by a pro{e«OT,1 many years resfident at Oxford, that nn original wicDtiSej investigator, unless he happened to be & man of social standing, would, on account of bis occupation, eimply ignored by the great bulk of his fellows theml Tlic «tatement, 'We do not want original researchers,'' implicitly cxprcj'scs a similar fact.
hiifi, though not least, of the ci rounistanc«M Jnflueftoing original research has been the formation of scientifio j societies. Italy was the first to establish on<;(vii. thcAcca-* dcmia del Oimento) in the times of Galileo and Torriwili. The English Royal Society was formed in the year 1645, Germany in lt)62 (-HtaViIitihc^d its Tmpcrijd Academj, and the Government of l-'rance in 1666 founded the FrvQch Academy of iScieuccs iu Paris. Dr. WalUs, one of the earliest memhera of our Royal Society, hat tfan described the character of its meeting : ' Our business ' (precluding raatteni of theology and Stat« affairs) to < course and consider of philosophical inquiries, and such m" rdited Chi^rcto : as pbysick, anatomy, geometry, iutn>'
JEtaty* en SmlaitmrBl ^ HtHnrch, p. 1S9.
I!(n.CX!(CB or LEASKEU SOL-IETIKS 0}i OESMUCU. 283 |
The Holy .Scripture, in fpeaking of the building Exod. 3f trie tabernacle, and afterwards of the temple of ^xv. s, g. Jcrufaieni that fucceeded it, tells us one circum- xxviiL^^o. Itance highly to the honour of architecture, which is, that God vouchiafed to be the firfl architedb of :hofe tv.'o great works, and tr.''ced the plans of ^hem hiirfelf with his own divine hand, which he iiterwards gave to Moles and David, to be the node's for the workmen employed in them. This jvas not all. That the execution might fully anfwer lis defigns, he filled Eezakel with the Spirit of God, Exod. whom he had appointed to prefide in building the ^^^^' ^^' ;abernac!e; that is to fay, in the exprefs words of :he Scripture, he had filled him "joith the Spirit of God n wifdom^ av.d iyi underjlanding^ and in knozvledge, md in all manner of -workmanfJoip. To dcvife cunning 'vorks, to 'xork in geld, and in filver, and in brafs. ^nd in cutting of flcnes to fet them, and in carving of 'imher, to "joork in till manner of zvorkmanfhip. And le joined Aholiab with him, whom he had filled with vifdom as zvell as all I he other Artifans, ihai they nay make all that 1 have cor.ir,ia;:dcd thee. It is fa id ii like manner, that Hiram, who was employed ■^" *^olomon in building the temple, was filled with 1 Kings, ./(fw, and uncUrfanding, and cunning, to work in ^"- '+•
all
>i4 OF ARCHITECTURE.
all works of hrafs. The words I have now quoted efpecially thofe from Exodus, fhew that the know ledge, fkill, and induftry of the mofl: excellen ■workmen are not their own, but the which they feldom know the origin, and make th nfe they ought. We muft not expeft to find fuc purity of fentiments amongft the Pagans, of whor we have to fpeak.
I fhall pafs over in filence the famous building, of Babylonia and Egypt, that I have mentionel more than once elfewhere, and in which brick wc ufed with fo much fuccefs. 1 fhall only infert hei a remark from Vitruvius, that has fome relatioh t them. Vitruv. Xhis excellent archite6t obferves, that the ar
r*'*^' * tients in their buildings made moft ufe of briclbecaufe brick-work is far more durable than that (} ftone. Hence there were many cities, in whic both the public and private buildings, and eve the royal palaces, were only of brick. Among many other examples, he cites that of Maufolu king of Caria. In the city of HalicarnafTus, faj he, the palace of the potent king Maufolus is walk with brick, though univerfally adorned with tl marble of Proconnefus ; and thofe walls are * fti very fine and entire, cafed over with a pjaifler ; iiTiooth as glafs. It cannot however be faid, th this king could not build walls of more coftly m; terials, who was fo powerful, and at the fame tin had fo great a tafie for fine architedure, as tl fuperb buildings, with which lie adorned his ca|: tal, fufHciently prove.
* Vitruvius U'ued ^c^o years after Maufolus,
I. Tcnoi
ot architecture; i2j
I. temple of Ephefus,
The temple of Diana, of Ephefus, was deemed one of the feven wonders * of the world. |
1 It was formerly usual to ascribe the deflection of the direction of magnetisation in the armature to a certain dragging of the lines of induction by the rotation of the armature ; this was then explained by the occurrence of what was called magnetic lag, with regard to which our knowledge is still very incomplete (Wiedemann, Elektricitdt, vol. 4, §§ 209-326 ; Ewing, Magnetic Induction, §§ 88-89.) That deflection may also partly be due to directional hysteresis, a phenomenon on which there is at present very scanty information ; it may be conceived as a more general case of ordinary hysteresis, in which, besides the numerical value and the sign of the two magnetic vectors, their direction also comes into account, which, in investigations on hysteresis is tacitly assumed to be invariably the same [compare Baily, Tlie Electrician, vol. 33, p, 516, 1894 ; H. d. B.]. Although there now can be no doubt that practically the armature current plays by far the chief part, yet a certain influence, even if it be a small one, must always be ascribed to those two factors, as well as : to the occurrence of eddy currents (§ 143), which will always produce a deflection of the direction of induction.
MAGNETIC CIRCUIT OF DYNAMO MACHINES
weak current is induced in the previous direction. Then follows the maximum itself, where the variation is infinitely small, and therewith the induced current vanishes. Finally, ® somewhat decreases, so that a weak current now passes in the opposite direction.
The best position of the brushes depends on a number of circumstances. In practice that position is adopted which yields the minimum of sparking. We shall therefore consider it as an independent variable which is exclusively determined by the attendant. The measure of the displacement of the brushes is the angle a which the neutral zone makes in the direction of rotation of the armature with its position of symmetry-- that is, with the ' plane of commutation ' with no current in the armature. The angle a is therefore positive if the machine acts as a current-generator with a forward lead of the brushes, negative if used as motor with a backward displacement. We shall in the sequel consider it as expressed in circular measure (that is, if 7 is the same angle in degrees, then a = 7T7/180).
§ 135. Calculation of the Armature-Reaction. -- Let the armature current TA be reckoned positive in the direction of the electromotive force induced in the machine itself. If, therefore, it acts as a generator, the current is positive ; if as a motor, it is negative. Let us now consider any closed path of integration through the magnetic circuit of the machine ABCDEFA (fig. 33), for instance, and first apart from the loop BCGH. The line integral M = O4 TT n I'M of the intensity produced by the field magnets (§ 126) is then, if the machine produces current, diminished owing to the action of those ampere-turns of the armature, which lie between the planes making the acute angle + a and -- a with the plane of symmetry (in this case the vertical plane). The other ampere-turns of the armature produce lines of induction parallel to the (vertical) plane of symmetry, and only, therefore, affect the direction of the flux of induction, and not its value.
FIG. 33
CALCULATION OF ARMATUEE-EEACTION 207
With an Edison-Hopkinson armature of m turns it may be shown, from the manner in which the curve of integration is involved with the windings, that this diminution of the lineintegral -- that is, in a certain sense, the ' counter-magnetomotive force'1 of the armature -- is equal to 0'4 am TA, in which, as has been observed, a is expressed in circular measure. Hence, with an armature producing a current the total electromotive force will be
(10) . . M = 0-^TrnI^ - 0-4<amI'A
With a series machine, in which the current of the armatures also flows through the field magnets, and therefore 1'jf = I'A , we have
(11) . . M = 0-4/; (vn - am) |
alternate rides for u and ▼. Qandsannaiely the two needles inclining opposite waya. -- Iks numerical fibres aie indksated in tha bbbs manner; and the words mailed oo the bosii are also pointed out by ringle or double tans of one or both needles towards tbem. Thsa single turn of the left hand needle tonardi ths right means '* I understand,** and two tannef the same needle to the left signifies '*Ko,"fks figure placed before the word ahowing the ibbh> ber of turns. -- When whole sentences are to be expressed by a few movements, it is dons If a system of codes, oontaiced in a bock, tk sentences being found by means of the letm of the alphabet Thus the lettffs b l s^gsfff **tl)e Eduiburgh and Glasgow Railway," m that code which has reference to dunes; ImI there must previously be two iotimatiooi^ -- fat, that the code is about to be used, nod, what code ; each of these intimatiaiB being by one or two signals. -- Over the left bad needle a cross will lie seen. That mdicstei a stop, which is made at the close of eveiy vnd ; and a second word is not sent ontil the kit hand needle replies "understand." If the le^j is **not undentand,** the word is repealed^-- Besides this method, giving sSgnab with tse wires and two needles, various others have bm devised, both before and since the patent, ir the system just described, was obtained. By sas plan there was a wire and needle for every kOer of the alpiiabet; by another, five wires sod i«t needles; by a thuti^ three ; and by a fboiti^ cab one. Tbe last mentioned, the inventleo of Xr. Bain, and named the smgk needh ^staa, ii aS used even on the doable needle telegfaph, whai one of the wues or needles is aocideataBy disabled. It also points out tbe ietten ef ila alphabet by the deflecUons of tbe needb; bet since, with one needle^ there are only two vanstions of movement, a greater nwntier of deflect tions are neoessaiy than with two needle^ sad it is therefore more tediooa. -- In one telegcs|k a small horse-shoe magnet b used inatead ef tin needle within the coiL In another a atrip «f gold leaf, forming part of tbe eonductix^ wii^ and a fixed magnet near it, perform tlie part d the needle and coiL In a third, tbe needles anef soft iron, rendered temporarily magnetie bytbs influence of a powerfid permanent magnet; their deflections bang produeed by eoUa. In a Ibertfc, the signals are made audibh by the needles anfting two bells of dUferent tones, one on Hm n^ tbe other on the left. In a fifth, the lettss ef the alphabet are marked round a ctioilar fis^ and the letters desired brought round and exhibited at an opening. The movcnia by dock-woik. The escapement, by motion is regulated, Is detached by an magnet at every soocessave transmission ef tbs current, permitting one tooth of the wheel to pass, and the number of is made to suit the pcaitiai of the letter en chi
TEL |
This law farther explains how, by means of air or water, bodies of different specific gravities, although mixed ever so intimately, may be easily separated. If pieces of cork and lead be let fall together through the air, the lead will reach the ground first, and may be swept away before the cork arrives ; but in a vacuum the whole would reach the ground at the same time, as is proved by the common experiment of the guinea and feather falling in the exhausted receiver of an air-pump. Again, when a mixture of com and chaff, as it comes from any threshing machine, is showered down from a sieve in a current of air, the chaff being longer in falling, is carried farther by the wind, while the heavier corn falls almost perpendicularly*. The farmer, therefore, by winnotoing in either a natural or artificial current of air, readily separates the grain from the chaff; and, if he desire it, may even divide the grain itself into portions of different quality. Similar to the operation of separating chaff from com by wind, is that of separating sand or mud from gold-dust by water: -- the soil containing gold-dust is first spread on a fiat surface, over which a current of water is then made to pass; which current carries away the lighter rubbish, and leaves the gold. If a mass of metal be afiixed on the end of a rod of wood, the rod then, whether simplyfalling through the air, or advancing as an arrow, will follow the heavier metdL as its point. The cork of a shuttlecock is always foremost for the same reason.
The instances enumerated under this head serve to show how many and varied the results may be which flow from a single principle.
When a fluid and a solid meet each other obliquely, the impulse or effect in still perpendicular to the surface of the solid, as if they met directly, but is less forcible as the obliquity of the approach is greater.
Suppose a 6 to represent the upper edge of a smooth board or of any flat polished surface standing in a current, the fluid approaching this surface, in whatever direction, must act upon it as if approaching perpendicularly, because, on account of its smoothness, the fluid can take Fig. 1 10. HQ h^ij Qf ij iQ pygi, ii endways, either towards am b.
,^ But the impulse of a stream acting on the surface will be less forcible if the surface be oblique to the stream, both because less fluid will touch, and because the velocity of the effective approach will be less. The line e d marks the breadth, and therefore force, of the part of a stream reaching the board directly ; and the shorter line/c marks the smaller breadth that can touch it, of a stream coming obliquely in the direction c b: in the oblique stream, moreover, if the line c b mark the whole velocity, the shorter line c a marks the slower rate of the direct approach of any one particle to the board. (This subject was treated of at page 57, under the head of RemftuHan of Ibrces*)
Hence the wind blowing upon the sail of the ship, however obliqnelyY
OBLIQUE PLiriD ACTIOIT.
Fig. 112.
always presses it directly forward or perpendicularly Fig. 111. |
Now, as the condensation produced at c c and the rarefaction at r r spread with the same velocity, it follows that they must meet along the dotted lines qqqq, drawn from the edges of the fork outward, and on the planes indicated by these dotted lines, there will be no motion of the air. This fact is shown by slowly rotating the fork around its length as a vertical axis, while the fork is held near the ear. Whenever the planes qqqq are opposite the ear, there is silence. In other positions of the fork, sound is heard. In one rotation of the fork, there will be four places of silence.
The same fact is also apparent on rotating the fork over a large tumbler whose mouth is partly closed by a piece of glass. The size of the opening in the tumbler is previously so adjusted that the air in the tumbler strongly resounds to the vibrations of the fork. This experiment is shown in Fig. 275.
If we adjust the openings in two wide-mouthed bottles to resound to the fork, and then arrange the bottles and fork as shown in Fig. 276, we shall have silence when the fork is so placed that each time a condensation enters one bot-
FIG. 275.-- ILLUSTRATING INTERFERENCE.
tie a rarefaction enters other, or vice versa.
the
Beats of Sound produced by Interference.
-- Interference of sound is
FIG. 276. -- INTERFERENCE OF SONOROUS VIBRATIONS.
386 SOUND.
also produced when two sounds fall at the same time on the ear, and one of these sounds is slightly natter or sharper ' than the other. This phenomenon is always observed when two organ-pipes, forks, or any two musical instruments are slightly out of tune. The experiment is readily made with two forks which, previously in tune, are put out of tune by loading the prong of one with a small piece of wax and thus flattening its note. This decrease in the frequency of the vibrations of the loaded fork makes it give wave-lengths in the air which are longer than those given by the unloaded fork.
The velocity of the sound-waves proceeding from each fork is the same ; but, as the waves are of different lengths,
FIG. 277.-- Two SERIES OP WAVES ILLUSTRATING BEATS AND INTERFERENCE.
it follows that at a certain instant the condensation in two waves, one from each fork, will reach the ear at the same moment. Their united action will produce a sound greater than that given by the vibration of either fork alone, and consequently we hear a louder sound. The same increase in loudness occurs when rarefactions in the two sounds fall together on the ear ; but just between these periods of increased loudness there is an instant when the sound becomes very feeble. These actions give to the sound a thumping character called beating.
Fig. 277 explains the action of the two series of sound-waves on each other. The longer waves are indicated by the full line ; the shorter, by the dotted line. These waves are going from A to B. An ear at B, as implied in the figure, is receiving a condensed half -wave from one source of sound, and a rarefied half wave from the other. A very feeble sound is the result ; but when by the forward motion of the
REFLECTION OF SOUND.-- ECHOES. 387
waves the place C reaches the ear, an intense sound is heard, for the two half-waves of the sounds are here acting together.
Reflection of Sound -- Like light and radiant heat, sound is reflected, and in such a manner as to make the angle of reflection equal to the angle of incidence. Spherical mirrors may be used to prove the principle. Determine the point to which rays of light converge if transmitted from some distant source of illumination to a mirror, and reflected therefrom. Substitute a watch for the light, and hold the ear at the point of convergence. The ticking will be heard distinctly, as if it came from the mirror, instead of the watch. The wet sails of ships, when bellied by the wind, have been known to reflect, to ears that happened to be at their foci, sounds produced at great distances. |
It would be a work better suited to the genius of an industrious cyclopsedist than the writer of a plain manual like this, to attempt numbering up all the “systems,” so called, that have sprung into a temporary and fleeting popularity during the last century in the direction of healing. Besides the well-known and widely-practiced methods included in the general term “allopathy” and the more special mode prescribed by homoeopathy, there are hydropathists of various descriptions, who place different degrees of curative virtue in springs, baths, packs, hot and cold water treatments, taken now internally, now externally, then together and then separate ; vegetarian healers, herbdoctors, counter-irritation healers, and healers by jumping, lifting, dancing, fencing, the practice of light and heavy gymnastics, and movement curers; abstainers, feeders, milk-diet doctors, fruit-diet doctors, psychologic, psychopathic, magnetic, and every other imaginable kind of healing system that the diseased condition of humanity and the easy character of its faith, or perhaps we might more justly say the despair of its desperate necessity, can suggest. To all and each, there have been a sufficient number of adherents to confer upon the passing experiment some interest ; but all except the long-tried and deeply engrafted systems of allopathy and the widely diffused methods of homoeopathy
THE STATUS OF MEDICAL PRACTICE. 177
appear destined to become the ephemera of the day, and pass away like the fashion of the hour in vanity and vexation of spirit. Our readers will doubtless ask where in this long category of systems and claims for systems do we place the subject of this book, namely, electro-magnetism ? We answer, nowhere as yet, -- that is, as a system. Electricity and magnetism are original forces, or original parts of one. universal force, and, being as old as creation, their uses are simply dependent upon the degrees of intelligence with which the age is prepared to apply them.
We have already made claim for electricity as being, if not the veritable life-principle in man, at least its analogue, and the nearest approach to it we can ever find in nature outside of man. We need not go over the ground of these arguments again ; suffice it that, being as we have claimed the life itself, it must be also the restorer of life and the restorer of life’s disturbed functional activities.
Its application as a therapeutic agent is, however, something very different from our recognition of its inherent virtues and powers. How far we can command its agency as a successful healer must depend upon how far we can learn to adapt it to the human system, engraft upon it scientific modes of application, and put it to its real use as a healing power.
That it can effect much in this direction has not only been proved again and yet again, but the proofs are multiplying daily on every side of us. Living bodies are struck dead by lightning, and half-dead bodies, as in paralysis, are restored by it.
Franklin, Galvani, Volta, Aldini, Colomb, Matteucci,
H*
ELECTRICAL THERAPEUTICS.
and hosts of modern scientists, pour in their wealth of testimony to its powers and possibilities over the nerves and muscles of the dead and living both. |
But in considering the preceding demonstration, one
might aver that it is indeed true that BN is the common
tangent of the circular waves in the plane of this figure,
but that these waves, being in truth spherical, have still an
infinitude of similar tangents, namely all the straight lines
which are drawn from the point B in the surface generated
by the straight line BN about the axis BA. It remains,
therefore, to demonstrate that there is no difficulty herein:
and by the same argument one will see why the incident
ray and the reflected ray are always in one and the same
plane perpendicular to the reflecting plane. I say then that
the wave AC, being regarded only as a line, produces no
light. Fora visible ray of light, however narrow it may be,
has always some width, and consequently it is necessary,
in representing the wave whose progression constitutes the
ray, to put instead of a line AC some plane figure such as
the circle HC in the following figure, by supposing, as we
have done, the luminous point to be infinitely distant.
E Now
26 TREATISE
Now it is easy to see, following the preceding demonstra-
tion, that each small piece of this wave HC having arrived
at the plane AB, and there generating each one its parti-
cular wave, these will all have, when C arrives at B, a com-
mon plane which will touch them, namely a circle BN
similar to CH; and this will be interseéted at its middle
and at right angles by the same plane which likewise in-
tersects the circle CH and the ellipse AB.
One sees also that the said spheres of the partial waves
cannot have any common tangent plane other than the
circle BN; so that it will be this plane where there will
be more reflected movement than anywhere else, and
which will therefore carry on the light in continuance from
the wave CH.
I have also stated in the preceding demonstration that the
movement of the piece A of the incident wave is not able
to communicate itself beyond the plane AB, or at least not
wholly. Whence it is to be remarked that though the
movement of the ethereal matter might communicate itself
partly to that of the reflecting body, this could in nothing
alter the velocity of progression of the waves, on which
the
ON LIGHT. Cuap. II 27
the angle of reflexion depends. For a slight percussion
ought to generate waves as rapid as strong percussion in
the same matter. This comes about from the property of
bodies which act as springs, of which we have spoken above;
namely that whether compressed little or much they recoil
in equal times. Equally so in every reflexion of the light,
against whatever body it may be, the angles of reflexion
and incidence ought to be equal notwithstanding that the
body might be of such a nature that it takes away a portion
of the movement made by the incident light. And experi-
ment shows that in fact there is no polished body the re-
flexion of which does not follow this rule. |
law, applicable to all gaseous bodies, namely, that the expansion is equal to ¥^ of its volume for each degree of Fahrenheit that the temperature is raised from 32° to 212°. If this column of air be 10 feet high, and have its temperature raised 20°, then it will expand ^% or ^¥ of its bulk ; so that its specific gravity would be diminished, and it would require a column of air 10 feet 5 inches high to balance a column of the external air 10 feet high, when the temperature of the latter is 20° lower than that of the former. But as the height of the heated column is limited by the height of the tube or chimney, which we suppose to be only 10 feet high, the colder column presses it upwards with a force proportionate to this difference in weight, and with a velocity equal to that acquired by a body falling through a space equal to the difference in height that two columns of equal weight would occupy, which in this case is 5 inches. Now the law of gravitation is this : that the velocity of descent is relatively as the square root of the distance through which the body falls ; and as the body falls 16^ feet in a second (or 16 feet, neglecting the fraction), the velocity will be, agreeable to the well-known law of gravitation, equal to eight times the square root of the height of descent, in decimals of a foot ; or 2 V g . hy where g is the distance through which a falling body descends in one second of time, namely, 16*09 feet, and h the height of the descent.*
In the case we have supposed, five inches is the height of the effective descent of the heavy column of air. This fall of five inches is equal to '416 of a foot; therefore, by the rule, 2 \/ 16 '09 x '416 = 5 '174 feet per second, or 310 feet per minute, will be the velocity with which the heated column of air would be forced through the tube or chimney
* See Chapter V., Part II.
OF PRODUCING VENTILATIOIsT. 359
under the circumstances we have supposed. If, therefore, the tube were one foot square, there would pass out 310 cubic feet of air per minute. This rate of efflux, however, is subject to certain corrections, on account of the contaminations which increase the specific gravity of the escaping air, and also in consequence of friction, arising from various causes, but more particularly in consequence of angular deviations in the tubes. In straight tubes, the friction is found to be in all cases directly as the length of the tube, and inversely as the diameter. In general practice, a deduction of from one-fourth to one-third of the initial velocity is necessary to compensate for these several effects, and to represent the true rate of efflux. The velocity of discharge per second through ventilating tubes, or chimneys, will therefore be found (after the difference in height of the two columns of air has been calculated in the manner already stated) to be equal to eight times the square root of the difference in height of the two columns of air in decimals of a foot ; this number reduced one-fourth, to allow for friction, and the remainder multiplied by 60, will give the true velocity of efflux per minute ; and the area of the tube in feet, or decimals of a foot, multiplied by this latter number, will give the number of cubic feet of air discharged per minute.
(350.) In calculating the rate of efflux of the air from any room or building, it is not merely the height of the room which must be considered, but the total height of the column of heated air. Thus, if the ventilating tube passes through another room or loft over the room to be ventilated before it discharges the vitiated air into the atmosphere, the total vertical height from the floor of the room to the top of the tube is the effective height of the column of heated air. If the tube in its course passes horizontally, this additional length
360 OX THE VARIOUS METHODS |
Passenger Depot at Oicenslmro, Ky., Louisville (s' Nashville Railroad. -- The passenger depot of the Louisville cS: Nashville Railroad at Owensboro, Ky., the data for which were kindly furnished by Mr. R. Montford, Chief Engineer, L. & N. R. R., is a single-story brick building with stone trimmings and roofed with slate, very similar, especially the ground-plan, to that of the depot at Hopkinsville, Ky., described above and shown in Figs. 617 and 618. The interior is divided into a ladies' waiting-room, 15 ft. X 18 ft., with a circular alcove at one corner in a tower projection with a prominent cupola; a ladies' toilet-room, 4 ft. X 7 ft. 6 in.; an agent's office, 12 ft. 9 in. X 13 ft. 6 in., with a prominent scjuare bay-window projection on the track side and three ticket-windows; a colored waiting-room, 12 ft. 9 in. X 13 ft. 6 in.; a general waiting-room, 17 ft. X 18 ft.; and a baggageroom, 13 ft. X 16 ft.
Passenger Depot at Niles, Alieli., Afieliigan Central Railroad. -- The jiassenger depot of the Michigan Central Railroad at Niles, Mich., shown in Figs. 619 and 620, copied by permission from the issue of the Railroad Gazette of April 29, 1892, is described as follows in the publication mentioned:
Fig. 6ig. -- Perspective,
BUILDINGS AND STRUCTURES OF AMERICAN RAILROADS.
The building, which was erected under the supervision of Chief Engineer J. D. Hawks, and his assistant, C. W. Hotchkiss, is made of Ohio brown sandstone, and is 98 ft. X 40 ft., with a wing 40 ft. X 24 ft. The tower near the centre is 68 ft. high. The baggage-room, 22 ft. X 35 ft., is 55 ft. east of the main building, the intervening space being roofed over.
The plan shows the main floor, 1)ut the rooms immediately over the ticket-office are shown below the main plan, and the rooms above the kitchen (w hich are occupied by the family of the manager of
f 25 H
EECONO S10RY
Fig. 630. -- Ground-plan and Second story Plan.
the eating-house), are shown in a separate plan at the right of the kitchen. The other features of the floor-plan are self-explanatory.
The interior of this building is exceedingly tasteful, the use of plate and stained glass and brass ornamentation having served to give a very pleasing eft'ect in all parts of the building. The wainscoting and ceilings are quarter-sawed and carved oak, and the walls are decorated in light terracotta. 'I'he building is heated by hot water. The tower has an illuminated clock, with 5-ft. dial.
The grounds around this station are laid out on a well-designed plan, and there is an alnindance of trees and shrubbery. There is a trout pond near the east end.
Passenger Depot at Port Huron, Mich., Port Huron &= N'orthwc stern Railway. -- The passenger depot of the Port Huron & Northwestern Railway at Port Huron, Mich., which serves as a terminal depot and general office building for the railroad, is a two-story frame structure, 32 ft. X 150 ft., costing finished complete in liard wood, with steam heat, etc., about $15,000, according to data kindly furnished by Mr. A. L. Reed, Chief Engineer. The first floor has gentlemen's and ladies' waiting-rooms; toilet-rooms; ticket-office; vault; dining-room; lunch-counter; news-room; kitchen; boiler-room; baggage-room; train-despatcher's office; conductors' room; and customs-officers' room. The second floor has the general offices for the road.
Passenger Depot at Sheridan Park, III., Chicago, Mihcaiikee (2^■ St. Paul Railroad. -- The passenger dejjot of the Chicago, Milwaukee & St. Paul Railroad at .Sheridan Park, 111., which is a jjicturesijue, substantially built single-story structure, with prominent clock-tower, designed by Messrs. Holabird & Roche, architects, is illustrated in the Inland Architect and News Record, Vol. 19, No. 2. |
We should now, according to Moses, proceed to the expansion, which is produced by
the mutual acting of the light and spirit on each other: but as that belongs rather to the agency than to the parts of the heav'ns, let us pass it by for the Pekin, and go on to consider.
. The ge i and their ables Un- derfland by the luminaries, the bodies of the
sun, moon, and ftars;; and by their fluxes, the flow of light that comes from each of them to us, As the misinterpreting of the words used in scripture upon this 0 has
occasion'd the chief perplexity and confufion that now attends the philosophy of scripture, tis therefore peculiarly necessary,
that a fair and clear interpretation be giv'n.
The case is this: tis evident that fcrip-
ture (at least according to the present tran-
slation) asserts, that the sun rises and sets;
speaks of the stars as in motion; and of the
earth, as if it stood still.” From hence prin-
cipally, it has been concluded by philoso- 7 pPhers,
The Philosophy of Revelation. 43
phers, that revelation was not intended to
speak properly upon natural subjects; but that it &ccommodates-. itself to ondmard appearance, and to the apprehension of the vulgar ; yea and many common christians to this day firmly believe that the earth really stands still, and that the sun. moves all
round the earth once a day: neither can they be easily persuaded out of this opinion,
because they look upon themselves bound to believe what scripture asserts. But I hope we {hall eably remove these obstructions, and answer these difficulties, by a fair and
close review of what revelation affirms upon
this subject. As for the earth's standing still or moving, that must be consider'd when we come to speak of the earth.. At present, we must only attend to the mean-
ing of scriptute, when it mentions the Jan,
moon and stars. Moses in Gen. i. 1418. sp oaks, of two
luminaries MeARoTH, or agent for
light, . which were ordain'd to rule over
the day and night, and to divide between
the light and darkness, Sc. But 'tis very
_ necessary, that we should distinguish between
luminaries and lights, as the scripture: atually does: see Pf. Ixxiv. 16. thou HAST MA-
cuin'd HaCINOTHA, TRE 'LUMINARY
MAOR, and the 80N SHaMeSH. If the conjunction [and] be copulative in this place;
en tis plain, the iner and the SHe- MeSH,
44 Philosophia Sacra: Or, MeSH, are distindt. Observe here, as we pass on, that MAOR fignifies a luminary or instrument of light, and AOR intends /zgb7. Now the sun, moon and stais are called, not luminaries, but lights, AORIM. P cxxxvi. 6, 8. This distinction is confirm'd Ezek, xi. All THE LUMINARIES MAORI, or L16nT AOR, in the heav'n Twill make black over thee : as that place is actually render'd in the margin. As therefore revelation thus distinguishes, *tis very impror for us to confound these two things to-
gether. But this is far from being the whole
evidence for this distinction. Let us see .
what words in scripture intend the lumina- Ties themselves; and what words are used for the fluxes of the light from them. This ought to be fairly review'd, because every one knows, that tho' the bodies of the sun, moon and stars, take up but a small part of the heav'ns, yet the fluxes of light from them reach even to the earth, yea, and diffuse themselves throughout all nature. Now, whoever reads his bible in the original with any care and attention, will presently see, that our translation has given us the same English word sun, for three distinct words in the Hebrew, SHeMeSH, Ha Ma H and *HeReS. Our translation has likewise
given us the same word moon, for two diffe-
rent original words Va Ra H and LiBNa H. And 'ts this has occasion'd all the confuby sion |
is chang'd into this N : M : : i, */\^ or M : N : : i : Vn.
go That is, the angular Motion of a Body, in an Ellipfe carried along, is to
its angular Motion in the fame Ellipfe at refi, as one to the fq^uare Root of a Number, which exceeds by three the Index of the Power, whofe Ratio the Force follows.
Therefore from the given angular Motion of the Curve, the Power that the Force follows is difcover'd ; and vice verfd, from the given Power is difcover'd the angular Motion of the Curve.
I fliall give but one Example, which has its Ufe in Aftronomy. Let a Body be given, which moves in an Ellipfe, which goes forward three Degrees in each Revolution ; that is, the Motion of the Body in the Curve is transferr'd 363 Degrees, whilft it would go 360 Degrees in the quiefcent Orb-, M therefore is to N, as 363 to 360 ; or as 121 to 120 -, and M M to N N, as 14641 to 14400 : therefore N = \^^l^, and the Power of the Diftance whofe Proportion the Force follows is -144-^-?- -- 3 = 414.1^ J wherefore the Force is reciprocally as D \^^\ z= D"' -l+i- = D*^4t- nearly.
go If the Progrefs of the Apfides at every Revolution, was 3 Deg. 2', 38',
^' the Force would be reciprocally as D "■ ^■^, nearly,
go. I will propofe another Cafe, which will alfo be of ufe in what follows.
Let there be a Force given, whereby a Body is retain'd in a quiefcent El- lipfe, and which tends to the Focus ; that is, which follows the inverfe
626. 657. Ratio of the Square of the Diftance *, and let the Force be fubftrafted which follows the dire6t Ratio of the Diftance ; from the given Forces it is requir'd to find the Motion of the Apfides, and vice verfi.
-- bDz=. :^- = -gi^ * : therefore
n = 4. And N : M : : v/ ■ -f; whence b
I -- 4. b
M-t-NxM -- N
The Force is as gj-^ >
fi = I ; b= -- b, m I
MM N N
4MM^NN 2M-I-NX2M -- N" The Motion of the Apfides is diredled the fame way as the Motion of g 668 the Body * ; becaufe as the Diftance increafes, the Force increafes whereby it is taken off, whereby the Diminution in the Recefs from the Center is greater than in the inverfe Ratio of the Square of the Diftance.
In
Chap. 23- of Natural Philofophy. 165
In the foregoing Example, in which M : N : ; 12 1 : : 1 20, = -7 685,
If the angular Progrefs of the Curve, at every Revolution of the Body 687.
in the Curve, was 3 Deg. 2', 38''; ^ would be equal to --^ -- 7^ •, that is,
the Force fubftrafted would be equal to fuch a Part of the other Force, as would retain the Body in the quiefcent Ellipfe,
Voe End of the Firji Booh
BOOK II. P A R T I. Of Innate Forces.
CHAP. I.
Of the Nature, Generation, and DeflruEiion of Forces in general, and their Differences from Preffures.
AQuiefcent Body refifls Motion, not whilft it is at reft, but whilfl it is acquiring Motion * : A Body in motion, reliils Acceleration and Retardation ; not whilfl it keeps its Velocity, but whilft its Velocity is changing, whether it is increas'd, or di- » J64. miniih'd *.
688. Therefore in general, A Body^ that acquires, or lofes Velocity, refijh J which Refiftance, in the laft Cafe, is call'd an Adlion.
For a Body which acquires Motion is faid to refift by its Inertia ; if it lofes Motion, it is faid to aft by its innate Force : but thefe
689. differ only relatively. The acquiring, and lojing Velocity, often ex- ■prefs the fame Change in Motion.
690. A Body which has ten Degrees of Velocity, and lofes four, acquires the fame Velocity in a Ship, mov'd towards the fame Part as the Body, with the Velocity ten, or a greater ; and that, which in the Ship is taken for the Aftion, whereby Motion is communicated, if we do not attend to the Ship is call'd the Effedl, by which that fame Motion is confum'd : that is, the Reiiftance of the Body,
♦ 689. of which we are fpeaking, whilft the Motion is chang'd *, is look- |
General Observation. -- We shall here remark, that the very considerable differences often found between the barometric and geometrical measurement, must not be entirely imputed to the method. The latter is certain ; but the observers of the barometrical heights have often employed imperfect instruments; in general, they have had no corresponding observations ; and they have scarcely ever taken into account the difference of temperature at the posts of comparison ; these differences need therefore excite no astonishment.
Remark We must observe that the French, in general, consider 28 Paris inches
as the mean height of the barometer at the level of the sea; and as the following remarks on this subject by Mr. Kirwan, may be of use to the reader, we here subjoin them : “ Sir George Schuckburg has shewn, from 132 observations, made in
Italy and in England, that the mean height of the barometer at the level of the sea, the temperature of the mercury being 55®, and of the air 62®, is 30 04 inches ;• we may then assume the height of 30 inches as the natural mean height of the barometer at the level of the sea, in most temperatures between 32® and 82° ; for if the mercury were cooled down to 32°, that is 23° below 55°, it would be lowered by that condensation only 0 07 of an inch ; and if it were heated up to 80°, that is 25® above 55°, it would be raised only ‘078 of an inch ; quantities which, except in levelling, may be safely disregarded.
“ The French have heretofore considered 28 Paris inches as the mean height of the barometer at the level of the sea, that is 29 84 English inches. But from 1400
• Phil. Transact. 1777 p. 580.
2 X
PHILOSOPHY.
observations, made at Rochelle by Fleurieu de Bellevue, and from five years observations made at Port Louis, in the Isle of France, he concludes the mean height of the barometer at the level of the sea to be 28 inches and two lines and ja of a line, in the temperatures of from 52“ to 55° Fahrenheit, or 30 08 English inches.* Hence we may consider, in round numbers, 30 inches as the standard height of barometers at the level of the sea. And knowing the true height of any part of the earth, we may, by subtracting that height, expressed in fathoms, from the log. of 30, viz. 7471 213. find the logarithm which indicates the number of inches at which, as its natural mean, the mercury should stand at that height about the level of the sea.
“Thus, supposing the height to be 87 teet, equal to 14'300 fathoms: then
4771-213 14-500 = 4755 713, which is the logarithm of 29-9; this therefore is the
natural mean height of the barometer at the elevation of 87 feet above the level of the sea.
“ Consequently, to all heights heretofore calculated by the French, above the level of the sea, 139-32 feet must be added English measure, when the mercurial height at the level of the sea was barely supposed to be 28 French inches.” (On the Variation of the Atmosphere, by Richard Kirwaii, Esq. LL.D., F.R.S., and P.R.I.A. Dublin, 1801.)
Hu/e to compute heights by the Barometerin English measures, by Dr. Charles Hutton.
To complete the foregoing account of the measurement of altitudes by the barometer, I shall here annex the method of performing that operation in English measures, either feet or fathoms, as extracted from my Philosophical Dictionary, article Barometer, or from my Course of Mathematics, vol. 2, p. 255, edit. 6th ; which is as follows.
1. Observe the degree or height of the barometer, both at the bottom and top of the hill, or other place, the altitude of which is required, as also the degree of the thermometer, for the temperature of the air, in both the same places. |
132. Each of the twelve signs of the zodiac is divided into 30 smaller parts, called degrees ; each degree into 60 equal parts, called minutes, and each minute into 60 parts, called seconds.
The division of the zodiac into signs, is of very ancient date, each sign having also received the name of some animal, or thing, which the constellation, forming that sign, was supposed to resemble. It is hardly necessary to say, that this is chiefly the result of imagination, since the figures made by the places of the stars, never mark the outlines of the figures of animals, or other things. This is, however, found to be the most convenient method of finding any particular star at this day, for among astronomers, any star, in each constellation, may be designated by describing the part of the animal in which it is situated. Thus, by knowing how many stars belong to the constellation Leo, or the Lion, we readily know what star is meant by that which is situated on the Lion's ear or tail.
133. Names of the Signs. -- The names of the 12 signs of the zodiac are, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pices. The common names, or meaning of these words, in tlie same order, are, the Ram, the Bull, the Twins, the Crab, the Lion, the Virgin, the Scales, the Scorpion, the Archer, the Goat, the Waterer, and the Fishes.
130. Explain Fig. 255, and show why the Sun seemi to pen through the ecliptic, when ^ Earth only revolvet around the Sun. 131. What is a constellation or sign t How is the Son*! apparent place in the heavens found 1 132. Into how many parts are the signs of the Kodiac divided, and what are these parts oidled 1 Is there any resemblance between the places of the stars, and the figures or the animals after which they are called ? Ex- l^n why this is a convenient method of finding any particular star in a sign ? 133. What are the names of the twelve signs ?
S5
sign! tf t\a ZaiHac.
134. Figures of the Zodiac. -- The im^naiy figures, lepresenting tbe 12 Signs of the zodiac, are delineated in Fiy. 266, with tie rays of the Sun in the center.
136. DENSiTr OF THE) Planbts.-- AstronomeM hare no means of ascertaining nhether the planets Im composed of the same l<ind of matter as our Earth, or whether their surfaces are clothed with vegetables and forests, or not. They have, however, been able to ascertain the densities of aeMral of them, by observations on their mutual attraetion. By dennty, is meant compactness, or the quantity of matter in a given space. (72.) When two bodies are of equal bulk, that which weighs mos^ has the greatest density. It was shown, while treating of the properties of bodies, that substances attract each other in proportion to the quantities of matter {hey contain. (132.)- I^ therefore, we know the dimensions tof several liodies, and can a»certmn the proportits in which they attract each other, thcdr quantities of matter, or densities, are easily found.
135. How hu th< imtitj of ibg plsnaii bmi ucHUiDad t VnaX it nHul br 4aa- >itrT In whftt propartion do bodtflt attnot «ach olhoi 1
THB SUN. 291
136, Thus, when the planets pass each other in their cireuiti through the heavens, they are often drawn a little out of the lines of their orbits by mutual attraction. As bodies attract in proportion to their quantities of matter, it is obvious that the small planets, if of the same density, will suffer greater disturbance &om this cause, than the large ones. But suppose two planets, of the same dimensions, pass each other, and it is found that one of them is attracted twice as far out of its orbit as the other, then, by the known laws of gravity, it would be inferred, that one of them contained twice the quantity of matter that the other did, and therefore that the density of the one was twice that of .the other. |
ay's ConsideriDg now our first equation W = KE established, ^ K being, as stated, dependent only on the nature of the electrolyte, we proceed to examine the constant K and its value for different electrolytes. The primary investigation is due to Faraday, who found that if A and B be two electrolytes, and if a quantity E of electricity decomposes a mass X of A and Y of B, then X and Y are chemically equivalent^ that is, are the amounts of A and B which would take part in a double decomposition between them. According to this view we have for any electrolyte W = /icE, where /a is the amount of the electrolyte chemically equivalent to 1 gramme of water, and c is the number of grammes of water decomposed by a unit of electricity, and is called the electrochemical equivalent of water. This appears to be always true, but the law as usually stated refers to the amounts of the ions separated. The most general statement which the facts allow is the following, known as Faraday's law : -- In any electrolytic decompositiofi whateveTy the mass w of one at lecut {usually of each) of the ions, simple or complex, separated by the passage of a q^ian- Hty of electricity E, is chemically equivalent to the amount of hydrogen separated by the same quantity of electricity in a VkUer voltameter, and hence w -- mhE, where mis the chemi-
nt
cal equivalent of the tony andh the electrochemical equiffolent of hydrogen.
Since water contains |th its weight of hydrogen A >- Ic .
Faraday admitted as electrolytes only bodies containing an equal number of equivalento of their components, and accordingly found that the amount of either ion was equivalent to the hydrogen evolved in a voltameter incladed in the circuit The seventh series of Experimental Researches was devoted to proving this most important law. Two methods were adopted -- (1) by collecting and measuring the products of decomposition, a voltameter being included in the circuit, and (2) by introducing an anode with which the anion could combine (as for instance a Pb anode in fused PbClj) a silver one in fused AgCl), and determining the loss in weight of the anode. By these means the law was proved for simple fused electrolytes, such as the chlorides, ko. Daniell extended it to oxygen salt solutions, and showed that they were decomposed into a metal and a complex ion, this last splitting up into oxygen and an anhydride which united with water to form the oorresponding acid, e.g.,
ZnS04=Zn-i- (S0,+ 0).
Matteucci and E. Becquerel added a large amount of evidence in defence of the law, which was demonstrated with great accuracy (to \ per cent) by Soret {Ann, de Chitn, et de Phys,, [3] xliL 257) for a series of copper salts; and by Btiff for great variations of current strength with silver compounds.
So long OS we confine ourselves to normal salts there is little difficulty about the stetement of the relation ; even with such compounds as the series of phosphates, the double cyanides, &c., which are decomposed as in the following table, the amount of either ion may be considered equivalent to the H of the voltameter.
Electrolyte.
Anion corresponding to H in volumeter.
Cation.
OtMerrer.
Solution of
NAiPOi
P,0. »
P,0.^ }
(P^.+n,o^+o..
H,CNH4),P,0r 1
AgCj+Cy. « 4(A1,8S04)+^ +1^
Na. Na. Na. Na.
Na.
K.
K.
K.
mttorf.
Daniell and Mm«, ► Pkii. Tratu,, _ 1644, p. 1
Hittorf.
NaPOj
NtaP.O?
*'"4' t^7
NajUPO*
NaHNH4P04... KjFcCy.
KAirCy*
K,A1,4(S04) |
(m) Enamels are glalTes containing fome opake fubftance, that is either. unvitrifiable or incapable of being vitrified with the degree of heat requifite for the fufion of ordinary glafs. Of the latter fort are almoft all the enamels ufed, they being moftly compofed of glafs mixed with metallic calxes ; all which, not excepting the calx of tin, by more intenfe heat might be reduce^ to tranfparent glafTes. The white vitreous compolition which is the bails of all enamels is prepared, according to Neri, by melting together a hundred parts of frit of calcined flints, one part of pure fait of t :rtar, and a hundred parts of a calx of lead and tin. This calx is prepared by calcining together equal parts of tin and lead, and reducing the fubftance fo calcined to a very fine powdeF, by -bruifing it, palling it .through a fieve, boiling it in water, decanting the water in which the finer parts are fufpended, evaporating the water, and drying the powder ; and by repeating the calcination and fubfequent operations upon the grofier particles, till they become as fine as the former. This compolition when fiightly fufed is to be reduced to a powder, and formed into all the various colored enamels, by adding to it coloring fubflanccs. Thus by adding to fix pounds of this compofition, forty-eight grains of magnefia, a jtneiubite enamel may be prepared;' an czure blue enamel, by adding to the fame quantity three ounces of zarTte, and fixty grains of calcined copper; a turquois blue enamel, by adding three ounces of calcined copper, ninety-fix grains' of zafFre, and forty-eight grains of magnefia ; a green enamel, by adding rhree ounces of calcined copper and fixty grains of fcales of iron ; a fiining black enamel, by adding three ounces of zafFre and as much magnefia 4 a purple enamel, by adding three ounces of magnefia; zyellonv enamel, by adding three ounces of tartar and feventy two grains of magnefia; z./ea- green or berylcolored enamel, by adding three ounces of calcined brafs and fixty grains of zafFre ; and a violet colored enamel, by adding two ounces ©f magnefia and forty-eight grains of calcined copper. Thefc are
ESSAY
ENS MARTIS, and ENS VENERIS. Thefe Latin names are given to the flowers of iron and of copper made with fal ammoniac, or rather to thefe two metals i'ublimed by this fait. See Flowers.
ESSAY. Eflays are chemical operations made in fmall, to determine the quantity of metal or other matter which is contained in minerals, or to difcover the value or purity of any mafs of gold or iilver.
We fhall treat fucceflively of each kind of elTay.
ESSAY of ORES. ' Before e%s of ores can be well made, a preliminary knowledge of the nature of the feveral metallic minerals ought to be attained. Each metal has its proper and improper ores, which have peculiar characters and appearances : hence perfons, accuftomed to fee them, know pretty nearly, by the appearance, weight, and other obvious qualities, what metal is contained in a mineral. A good effayer ought to be very intelligent in this matter, that he may at once know what the proper operations are which are requifite to the effay of any given mineral. Some remarks may be found on this fubjecl: under the article Ores.
As metals are very unequally distributed in their ores, we mould be apt to make falfe and deceitful eflays, if we did not ufe all poffible precautions that the proportionable quantity of metal produced by any eiiay fhall be nearly the medium contained in the whole ore. This is effected by taking pieces of the mineral from the feveral veins of the mine, if there be feveral, or from different places of the fame vein. All thefe minerals are to be {hook together with their matrixes. The whole is to be well mixed together, and a convenient quantity of this mixture is |
Ml adfifrvd'tOrruB ou^ it will only drop from it slowly |b^(^j|,^e stnh^s jldiSMM9 it vvUl run out in a continued Atream/ Tki^ opi efc t irifl ft n j^itto^ differing from the gepen^ prin^pli^ i^j^g^- 9dtaifligha«e a^t yet been sufficimliy investigali^j^oi^^^^^^ htfjediapfm4 upon tbe general principle of alKmc^o^ ^l &)f^(i^f]|i- Xim^iibiofebb^di^ have to adhere togethev^ (K^najn f^gi^cp^r^wd loolMrsbJi^ )^% degree, while some se^pi en^q^jf^ffkk i^^Ag 3i|urQp^)i^t3r^aad eadeavour to fly from eac^ot^^c ^^b^l^l^t a^ i^yteftt Tyy, fai my opinion» to depend^na^ ^p9Bdtb^c^m^l fltfuij>4»«iii^h0ntcal propeitie» of bodieii; :fm4.#^<^lS^ st^e ifenolpf^eKpenttients have been «oourately-9^d^ H<V^lh0J9 Tsin UAoditlfimi^ to lay^ down any general rule^>fnr .#9bdp9ik $%c^|^Sdl^D ^sf^^Mm'oi emllary attraction. . v .i^-r^-i-^ .'B-'fTfiHDsrn is^dj'-' oJ ,iA«ep4«> ^ahmqgeneous is a teim PplN»N''^^~e^lifl^ ^^ yjM^iiwA densities thfooghout,; OT:9^(mCfpQ^f4'i9iia^S^<^^ i0ilfiffambtB of the jNuoe nature i- ihvahrw^mifa ^^9mf(iki^9mfi9iA
3*i*»i^p<ni»gei«w*l»dies; aii^.4bi9.4(!np]i|^N^i9 ispj^f^^^o ^^Jfe^gsiii»mou% or that which is.^19^ «iIbpf^ti»i«IWfti<yfrS|*-
2h;, appendix.
btiiiiccb difleiing from each other Id their nature and qualities ; thus, a ball of lead is an homogeneous body ; while oiie nmde up of a mixture of metal, wood, stone, kc. such as a building, or a ifaip, is called an heterogeneouz bodif : and this is what is meant in Cor. 3. of the same Proposition.
Prop. 84. Cor. 3. -- Ihxs Cor. maybe very aptly illustrated fay the motion of an arrow, where, from the head being much teafier than the shaft, the centre of gravity is very near the head, md te centre of magnitude that point which is at equal distanceff (ram the two extremities of the arrow ; hence, in its motion, the ceitie of gravity, or that point near the head, goes foremost, while iie centru of magnitude follows it as here stated.
Prop. 84. Cor. 4. -- This Cor. seems to imply, that if the body \vhich is placed in the fluid is of either greater or less specific ^- vity, it will be always in motion; whereas, what is meant, ii lin^y that if the body is heavier than the fluid, it will continually sink in it till it reaches the bottom of the vessel which contains the ntnd; er, if it is lighter than the fluid, it will always rabe towards the suifiioe,-1et it 1)6 placed in any part of the fluid beneath that surfiuse ;' but fluit if it is of the same specific gravity as the fluid, it will remam At^estt if placed in any part, and will notliave a tendency either to descend or ascend.
Prop. 85. -- On the principles shewn in this Proposition depend the use and construction of the hydrostatic balance^ or machine for asccrtaiuin.? the specific gravities of bodies, and, consequently, as applied to tne arts, the quantity of any alloy mixed with tae gouL or suvcr which we manufacture, either into coin, or difierent artides of utility or ornament; the principle of which is as follows. First, we weigh the article in the air, in the common way ; then, suspendiug it from the scale by means of a horse hair or otherwise, we let it hang in a vessel of water, and balance it b^ weights in the odier scale, and from the quantity of weight lost m weighing in tiie flutd we estimate its specific gravity ; and, consequently, knowing by experiment the specific gravity of gold or silver, we are eiiiaUM to find the quantity of alloy used. |
R is very small compared with Z this becomes 7^= 2 ir^/Ls, The period of oscillation set up in any circuit may therefore be controlled by increasing Z. By this means Professor Lodge succeeded in getting periods a considerable fraction of a second in length, but in general the discharge of a condenser may be said to be practically instantaneous. If iron cores are used in self-inductance coils for use with oscillating discharges they must be very finely subdivided, or the excessive foucault currents set up in the outer layers of the cores screen the inner parts from any magnetic eflfects.
Plff. P
. The formulas for the discharge of a condenser, through an inductive circuit, apply equally well to the charging current, which may be logarithmic or oscillating depending upon whether
-- - ^ -- • Figure F shows the dying away of the charge and 4Z '*^Zj'
the oscillations of the discharge current in an oscillating circuit. The curve which touches the maximum points of the quantity curve is logarithmic, and a similar curve similarly touching the current curve would be logarithmic. Figure G shows the growth and dying away of a current due to a transient pressure in an oscillating circuit. Figure H shows the curve of discharge and of the discharging current in a non-oscillating circuit.
7o8
ALTERNATING CURRENTS.
The oscillating electric circuit may be likened to a pendulum or an oscillating spring (Fig. /). Such a spring will have a period of vibration dependent upon the mass (inertia) of its
Figr. o
load, its elasticity, and the frictional resistance to its motion. The formula giving its period is exactly similar to that for the period of an oscillating discharge, putting mass for self-inductance, friction for resistance, and the reciprocal of elasticity
Pigr. H
(compressibility) for capacity. When the spring stands at its neutral point it is analogous to the condenser when discharged. Extending or compressing the spring is equivalent to charging the condenser. If the resistance to motion is small and the
APPENDIX D. 709
extended spring is released, it will oscillate through decreasing
distances with an isochronous period until the energy stored
in the spring by its extension is used up in
overcoming the frictional resistance to its
motion. If the resistance to its motion is
increased, its period will be lengthened and
the number of oscillations decreased. While
if the resistance is made sufficiently great (as
for instance, if the spring is immersed in syrup)
the motion will be dead beat This condi- ^'
tion is analogous to the electric discharge in a circuit in which
This subject is treated at great length in Fleming's Alternate Current Transformers, Vol. I, p. 364, et seq, ; Bedell and Crehore's Alternating Currents, Chaps. 7 and 8 ; and Gerard's Lemons sur VElectricite, 3d ed.. Vol. I, p. 253, et seq.
APPENDIX D.
ELECTRICAL RESONANCE.
The deductions of Chapters III. and IV. of the text have shown very clearly that self-inductance and capacity in a circuit may be made to neutralize each other when a sinusoidal alternating pressure is applied to the circuit, and the selfinductance and capacity are constant. In this case the selfinductance and capacity act in opposition, so that at each instant energy is being stored or released in the magnetic field at exactly the same rate as energy is being released or stored in the charge of the condenser. The self-inductance and capacity may therefore be said to supply each other's demands, and the pressure impressed on the circuit may be wholly utilized in doing work on a non-reactive receiver, such as incandescent lamps, and in heating the wires of the circuit.
710 ALTERxVATING CURRENTS. |
1 pound 1 ounce 1 drachm
Troy Weight
1 lb 2 oz. 11 dwt. 16 gr.
Apoibecarias'.
1 ft2S 4 329
0 0 7 0 17.5gn.
Apoihecariee*. 1 pound
ounce
drachm
scruple
Troy Weight.
1 pound
1 ounce
2 dwt. 12 gr.
Aroirdupoia.
13 oz. 2 dr. 17.8125
Drench Decimal fVdghL^Granmt » 15.4063 Troy Ormiw.
-» 0.0154 grmina
«B 0.1540
«B 1.5406
Milti|;ramme Cent^ramme Doci|;ramme Gramme
Appndig.
MEASUBES.
The Imperial Standard Gallon containa ten pounda Aroudapoia weight of diatiUtd mrater, weiched in air at 62^ Fahr. and 30^ Barom., or 12 lb. 1 ounce 16 pennyweighta and 16 graina Troy, >■ 70,000 graina weight of diatilled water. A cubic inch of diatilled weighs 252.458 graina, and the imperial gallon contain! 277 274 cubic inchea.
DMtiUed Waur.
hnptrxal Measure.
1 Quarter ae 8 fiuahela.
1 Bushel SB 4 Peeks.
1 Peck * 2 Gallons.
1 Gallon SB 4 Quarta.
1 Quart ^ 2 PinU.
or.
Gf&int. Aroird. lb. Cub. Inch.
Pirn.
Quart.
OaUa. Pec
87ri0 » 1.25 = 34.669
IB
OS 1
yOOOO -- 20 = 554,548 WOOOO = 80 =. 2218.192
OB
=: H r. 4
44dOOOO » 640 » 17745.536
MB
Bosh. Or.
•^pothecaritt* Measure (London Phannacopoeia).
The gallon of the former wine meaaure, and of the present Apothecariea' measure, oonina 58333.31 grains weight of distilled water, or 231 cubic inches, the ratio to the impeviml gallon being nearly as 5 to 6, or aa 08331 to 1.
Gallon.
1 Gallon 1 Pint 0 1 Ounce f S 1 Drachm T 5
8 Pints. 16 Ounces.
8 Drachms. 60 Drops, or Minima.
Pinu.
OuncM. Drachma.
Of*
Minims. Or. of Dlat Water. Cub Inch.
=r 8
60 = 56.9(i « Oil
t)r€nfk Deeinud Measure of Capaeity, Litre = 61.02525 BriHsh cubic tncftet, or
15400312 grains of distUled waUr.
Millilitre
0.06102 cubic inchea.^
Centilitre
SS5
Decilitre
sss
Litre
rs
TUIe siknoing the }f eight in Grains of various Measures (Jlpoihtcariss) of different
Fluids,
IDwUtled Water • • - uric Ether - - •
IcKibol
of Ammonia -
orialjc acid - . - -
add ....
■eid . - .
RpedSc Ormviljr.
1 Plat
Weight in OnJM of
1 Ounce.
1 Drmcboi.
41.0k
105 J27
1 Mialai.
Fig. I, «» ire
.Spparalaa for ottainitig Polattimm.
bm. luallfablfl iron, about 12 inches luns,
Iroa at leatl lfar«e eigblhi of id incli thick. A (id ii
it, and ihii ia lecuted bj bd iron rod paasing ihrouab lw(
npjwr part of Ibe pot. A gun-barrel paaaei from th'
pot made of tb
n diameler ; th itely (
npper part of Ibe pot. A gun-barrel paaaei from tnn coTsr to the rC' ^ \
ceivsr. Tlie reeeiver conaliU of two piece* It ii oiade ot tinned c<^ P^'n
Fl;. 4 per. The pii!i:e(Fig. S)iialliinparallElopipcd, 10 I I
/i h- pi inches long, i5 or6 broad, and II thiclt. It ta nhut I I
A- --i-f-i -- at the lop and open al tho baltom. It ia divided by I j
(tip ^ '\ X) ' diaphragm, n, to within one ihjrd of the bottom. r~^
On one iide is a amal! boJe into, which the end of ■'
tha gun-barrel enten, and to wl better, fitted bj grinding. Oppoaiie ti with a cork through which an iron w alio tliroiigh a cork fitted into the holi of thii wire !■ la keep Ihe gnn-bsrrrl H le other part of tha receiver, open above, and ahi t exseltj. A few inchei of napblba a pinced in ix; l>eing well luted with A bent giaea lube prot-eeds from 2 i -■ ' filled wilh naphthi
Fig. 4 alMwa the arrangement of t> '
nelted ; with i]
luted air-tight, o .
ia another Oficiuag. faM
' tight. It MB
1. TUm
claj lula miied with abuut o
iron filing! and rbarciial. and
into piecea about an inch in Icnglh. Tkii a
bound round again witli wire, and the sMt
rubbed over wilTi lute. It ahould be allon^B
dr^ a da<r or two belbre uiin^i anil the cncta
ahould he filled up
'I'be iron pol i» placed, as repieaenteif, i ■ piece of &T0 brick, and fix Elav. The bodjofihenirnBc '~:^neB long, 15 brood, t~ ' '
from
Ibe fun
•quam (iiuide).
'oryco
e may br than I; i8 deep ; ibt wiSk il Ibe flue otackM |
not evident that y'^y, it mi^ be shown thus. In the time I Og, Oz have turned through a veiy small angle tf^weosXl, hence, as in iransfonnaiion of axes,
jr'syeostf-tsintf,
which gives /sy when we reject the squares of $,
267. In many cases it will be found convenient to refer the motion to axes more generally placed. Let 0 be the origin, and let the axes be fixed relatively to the earth, but in any directions at right angles to each other. Let $^, 0^, $^ be the resolved parts of tt> about these axes, then 0^, d,, d, are knovm constants. Alter substituting from Art 244 in the equations of motion given in Art, 245 we get
ON MOTION RELATIVE TO THE EARTH. 217
For example, if we wished to determine the motion of a projectile, it will be eonvenient to take the axis of 2 vertical and the plane of as to be the plane of projection. Let the axis of x make an angle p with the meridian, the angle being measured from the south towards the west. Then
tf^=ciico8Xco8/3, 9, = - 61 COB X sin /3, 9,= -(iisinX.
These equations may be solved in any particular case by the method of continued approximation. If we neglect the small terms we get a first approximation to the values of {x, y, z). To find a second approximation we may substitute these values in the terms containing to and integrate the resulting equations. As these equations are only true on the supposition that a* may be neglect^, we cannot proceed to a third approximation.
268. Ex. 1. A particle is projected with a velocity F in a direction making an an^ a with the horizontal plane, and such that the vertical plane through the direeiion of projection makes an angle /? with the plane of the meridian, the angle /3 being measured from the sonth towards the west. If 26 be measured horizontally in the plane of projection, y be measured horizontaUy in a direction making an angle
/3+- with the meridian, and t vertically upwards from the point of projection,
prove that
x=iVcoaat+l VBUicLfi-^gfij wcosXsin/S,
y= ( Fsino(*-5grt» j wcosXco8/3+ Fcosat'wBinX,
t^Vmnat-^gfi- Fcosa^wcosXsinjS,
where X is the latitude of the place, and u the angular velocity of the earth about its axis of figure.
Show also that the increase of range on the horizontal plane through the point of projection is
4w -J sin /3 cos X sin a f ^ sin' a - 00s' a j , and the deviation to the right of the plane of projection is
4w -T- sm' a (cos Xcos 3 --=,-- -f sm X cos o). 9* o
Ex. 2. A bullet is projected from a gun nearly horizontally with great velocity BO that the trajectory is nearly flat, prove that the deviation is nearly equal to JUu sin X, where Jl is the range, and the other letters have the same meaning as in the last question. The deviation is always to the right of the plane of firing in the Northern hemisphere, and to the left in the Southern hemisphere. It is asserted (CompUi Rendtu, 1866) that the deviation due to the earth*s rotation as calculated by tluB formula is as much as half the actual deviation in Whitworth's gun.
218 XOnON IN THREE BDCEKSIOHS.
Ex. 3. A spherical bullet is projected with so great a Toloeity that the : of the air muBt be taken into account. The reeistanoe of the air being airamed i
be (^^^ , and the trajectory to be flat, proTO that^ neglectiDg the effeeta of ftlj rotation of the earth,
«=i;log^l+j^
* 9^ I t\ «* tv 2«8inj8ooeX-., { x -. f=a;tano-|^(« *-2j-l) ^ ti(el---l).
These are given by Poisson, Journal Polytechnique, 1888.
269. Let us apply i^hese equations to determine the effect d the rotation of the earth on the motion of a pendulum. In tUi as in some other cases, it will be found advantageous to refer th0 motion to axes not fixed in the earth but moving in some known manner. Let the axis of js be vertical as before and let the axe§ of X and y move slowly round the vertical with angular velocity o) sin X in the direction from the south towards the west. In this case we have
dj = (» cos\ 008/3, dj,=* -- « cosX Anfi, and ^3 = -- o) sin X + 0) sin \ = 0, |
eras preparation.
2 pee rence wy
LALO LE LO A A an AOE wee me OO Ag ee wee , ; r <r we iA . ol ri , Me ¢ . ’ “Tors fowiheceseeh
a ; .
i neither apenas anneal Lin li ater pres tn ein ig
r a : ii - aT aia.
INSTRUCTIONS GIVEN IN THE i
MR. FREDERICK HOLMES, cuca Chemist, and Lecturer on Natural Philosophy & Chemisty, , ALFRED STREET, BEDFORD SQUARE. '
*,* It is necessary to direct the attention of Purchaseré to an inferior eH
badly-constructed Instrument made to imitate that of Mr. F. HoiMEs'’s, and -
sold at a reduced price. Should any difficulty arise, a post-office order sent direct to Mr. FREDERICK HoLMBs, will receive immediate attention by return |
June, 1852.
of post. ‘e Ee |
Lixivium, is a Liquor made by the Infufion of Affies, or any burnt Subfiances, which is more or lefs pungent and penetrating, gs it is impregnated with the Saltg and fiery Particles abounding there¬ in. And what is left, after tho Evaporation of fuch a Liquor, is call’d a
Li xi vial, or
Lixiviate Salt | fuch as all tfiofo are, which are made by Incinera¬ tion.
Lobe, fignifies any Body turn’d of a roundifh Shape , whence Roots of Plants are thus call’d in Botany : And in Anatomy, di¬ vers Parts of the Body are thus diflinguifh’d 1 as the Lobes of the Ears, Lungs, Liver, and the like 1 which Parts fee. Bidloo ufes the
LG ( 249 ) L U
diminutive Lobellus , or little Lobe, ft? r the four Procefles of the Brain.
Loch, and Lohoeh , are Arabian Names for thofe Forms of Medi¬ cines, which are now commonly call’d Eclegma s Lambatives , Linetus's , or the like ; which fee.
Lochia , Leches, Signifies fuch E- vacuations, as are peculiar to Wo¬ men in Childbed- The nearefl De¬ rivation of this Term, that bears any Affinity to the Senfe it is ufed in, is from Ki'XpyLdLi, cubo , to lie down. See Placenta.
Loeulamenta , ftriftly fignifies lit¬ tle Pocket#' ; and thence the Term is made Ufe of in Botany, to exprefs thofe little diftinft Cells or Partitions within the common Capfula Semina/is of any Plant ; as jtliofe within the Seeds of Pop¬ pies, &e.
Lohoeh . See Loch.
Longevity, fignifies long Life, to procure which, Abflinence and Regularity are fuppofed to be high¬ ly conducive.
LongiJJimus Dorfi , is a Mufcle of the Back, that, at its Beginning, is not to be feparated from the Sa- crolumbalis , ariiing with it from the hinder-part of the Spine of the Ilium , and upper Part of the Os facrum , and, as it afeends, it gives Tendons to each tranfverfe Procefs of the Vertebrae of the Loins, thorax, and Neck. In Conjunc¬ tion with fonts others, this helps to keep the Body ereft.
Longitudinal, Lengthways, is oppofed to Tranfverfe.
Longus Colli , is a Mufcle, that ip fatten’d to the five upper Verte¬ bra of the Back, and to all thofe cf the Neck ; but becaufe the laft are more moveable than the firft, therefore, they are its Infertion, ^ndr fhofe of the Back its Origi¬
nation. This helps to bend the Neck.
Longus Cubit & us, is a Mufcle, that in Conjunflion with others, extends the Cubitus. It arifes from the in¬ ferior Cofia of the Scapula , nigh its Neck, and pafleth betwixt the two round Mufcles. It defeends on the Back-fide of the Hutnerus , where it joins with the Brevis and Brach tor¬ us externus.
Lotion, is a Form of Medicine compounded of aqueous Liquids, ufed to wafh any Part with, from lavo, to wafh.
Lozenges, is a Form of Medicine, made into fmall Pieces, to be held or chew’d in the Mouth till melted or watted.
Lubricity, is a Property chiefly of fluid Bodies, which makes them foft and yielding, as in Oils and the like, from Lubricitas Slipper! ~ nefs.
Lues , fignifies a Plague, qr Contagion ; but, according to modern Ufe, efpecialjy when join’d with Gallica, or Venerea , means only the Pox. There are various Opinions of this Difeafe, as to its Caufes and Propagations chiefly, which haye their Founda¬ tion in nothing but Conje&ure. And many Cafes, that pafs for a Cpnftitu ioij - Pox, feparate from a Gonorrhoea , are not dittinguiihable from fome Species of a Scurvy ; and are very often nei¬ ther from Infection, nor capable of communicating one : Such are to be managed, as the Scurvy, Leprofies, Struma’s, and the like ; and feldom require any Thing peculiar to Venereal Diforders. But where it is remarkably , and certainly from Venereal Foulnefles, it is to be managed ac¬ cording to the Appearance of Symptoms, either by Evacuation,
L U
Detergents or Abforbents, or all together. |
Profi.'Httor Wobcr haa observed that, if an induced current ia appUod to the spinal cord, one electrode being directed to the upper, and tlie other one to the lower extremity of the cord, aJl the miisclcfl of the tnuik and of the oxtreuiitie* ore thrown into tetanic conrulfliona. The stuno occnra if one electrode is placed to the anterior, and the other one to the posterior, surface of the upper portion of the cord ; and likewise when both electrodes are apjilied to iU lower portion, pn-vid.'d that (lie integrity of thv organ haa not been destroyed. Hence it would rosult that the cord ia the nerrous centre for all the muscles of the trunk and the extremities ; for if the cord were only the common trunk of all the motor nerves emerging
ci4r. u.]
THK flPIXAI. CORD.
from the Tcrtcbml catuU, tlio application of the induoMl cturent to the lower portion of tlie cord wonJd only prodace a conTaUioa of the hind-legs, bat not of all four extremitiea. If, however, the itpiiiiU cord i» divided in the middle, nnd the lower half 'u Uicji submitted to Uie eloctrie atimuluB, only the muscle* of tho hind-le|*8 enter into oontruction ; aod fvon if both piirt« of tho (.'vrd are made to touch oti>- another closely atthoxe points where the section ]i I i> II made, eo that there ia no impedtment to t)j I !-. of the electric current to th« upper |>onioti 'A t iie cord, the muwJe* of tho upjKT vxtrewitied iievL-rtheleM remain perfootly quiet. From this Profemtor Weber has inforrud that the conmlsions daieribed are not prodaoed becanae the electiiv enzreot is trvismitted from the coni to the motor nerrea, hut because the paMnu^- of the electric current excites the action proper of the cord, which in its turn excites the property of the motor nerves to produce commotions of the muscles. He also obserre*! that the tetanic coDTulsions produced in tho extremities bj the same ueaiui continued for a Certain time, sst half a minute, afW the cessation of tJie currt'nt ; while, if the unterior mota, or the mixed nerves were excited, tlie commotlous dtiui{K peared immediately aAer the circuit had been bn>ken. If the s|iLnal cord be subjected to tho action of a continuous current, convulsions of the extremitiea ire produced on making the circuit, but if the current continues to traverse the cord, an inhibitory
t. a
14S
ELECTRO-PHYSIOLOOT.
[OB&F. R.
effect is mused, whaU^rer nuiy be ihe |M>int to wbicb the polett ari> din>ct«<i. As lonj; us tlie cord ia traversed by the continaous curront, it rQiniiins ioBensible to a stimulus which may be nppliod to it. Thuti we may prick the cord by a pin or excite it by an induced curront, and tlic t^xtremitiefl will nererthcIcHs a'mniu purlV-ctly qui»t ; but ut the cessation of tlie continuous current, mcctumieol or electrical exdtaiion of the cord will again give rise to tetanic convtilaiona of the limbs. It was first pointed out by Baierlacher ' that tliis diminution of excitability is confined to the spinal cord, and does not extend to the motor nerves and muscles ; for if an induced current ia applied to the motor nerves of the hind legs, while at the same time the cord is being tmrersed by a continaous current, commolioiie ore prodnoed in tho muscles the nerves of which are submitted to the action of the induced current. The inreree continuous current appeon to hare a more powerful inhibitOTy action on the spinal cord than tlie direct current.
Weber's eii)eriment«, although carefiiHy performed, have not been entirely eonflrnied by other obserrors. Thus Tan I>een, Sehiff, and other physiologists contend tliat the substance of the cord itself does not respond at all to the electric stimulus, and tliat if convolsious are observed in consequence of such ma application, this is due to the propagation of the electricity to the roots of the spinal nerves. En-
■ Die Indndiaiit-ElfktririUt Kumbere, I8A7. p. 101.
tAt.U.']
THE SPIKAL OORIX |
with my right hand^ she had the peculiar secondary sensation, which I had also met with in Miss Sturraann, that this hody seemed to her to become li^ht, almost like down ; on the other hand, when I touched it with the left, it became heavy, and seemingly much heavier than it naturally was. Without wishing to enter more minutely into this at this moment, I nevertheless must mention it, insomuch that it furnishes another character to the opposition of the hands, in a kind of attraction and repulsion. Yet, different as she found my hands in their effect upon her, she perceived no less difference in her own. When I placed in one of her hands things like * iron pyrites, selenite, reguline metals, charcoal, <fec., they produced sensations very unhke those which they caused when I bade her transfer them into the other, although no kind of weakening of one or other half of the body in any way existed in her.
88. I have very recently gone through an investigation of this particular with Mis» Reichel, and traced it to further development than in any of the former sensitive persons. She found not only her right hand, but the whole right side, from head to foot, opposed in all its properties to the left ; nay, the mere approximation towards her of my right or left hand, affected her in an essentially different manner. I. shall detail this more fully in a subsequent treatise ; here, where we are concerned merely with the proof by facts of a magnetic polar difference in the transverse direction in the human body, I must be content to state, that the observations on Miss Maix were repeated, found the same, and confirmed anew.
89. It appears from all these investigations, that all the symmetrically placed organs of the animal body, so far as they were here investigated, but especially the hands ^ exhibited a difference which is caused by a magnetic polar opposition ; and that conseqiientlj/ a dualism of the fundamental force now wider consideration exists between them^ wholly in the way that we have found it to occur in crystals,
90. I iiave shown above, § 41 and § 63, that the terrestrial magnetism has no observable influence upon crystals, and not the slightest directing power. The same holds good in relation to the force of the hands. The force which I exert actively with my hands is always equally effective in all places and positions that I assume. -- Neither can I perceive any influence upon me passively : I have tried lying down to sleep in various directions, but to whatever quarter of the heavens I turned, I slept equally well : and the perfectly healthy man, who perhaps never is sensitive, undoubtedly never feels the least influence of the terrestrial magnetism, however actively and variously this re-acts upon the sick. Neither can I detect in animals
.^■i^iM
OF THE ORGANIC FORCE. US
anything which indicates the least dependence upon terrestrial magnetism. If a free sense were devoted to this influence, we might expect to find it in larvse, which are blind. As silk is cultivated on mj estates, I had many opportunities of observing the deportment of these so low organisms in all stages and conditions. Yet, even in spinning and changing into the chrysalis, the animal never selected any definite direction, but placed its cocoon irregularly in all possible directions ; not even a majority exhibited a preference for any particular direction during their dormant state. Therefore, the crystaliic force and the force of the hands agree perfectly in this insensibility to the universal magnetic force of the earth. |
Electricity is no exception to this law. In order to ascertain its full effects on the system at large, and to determine its position among remedies, the applications must be made in such a way that the whole system shall, so far as possible, be directly or indirectly brought under its influence. This is best accomplished by the methods of general faradization, central galvanization, and the various methods of franklinization that are hereafter to be explained in detail.
In making a detailed comparison, therefore, between the effects of electrization and the effects of recognized tonics -- quinine, iron, strychnine, physical exercise, sunlight, cold bathing, etc. -- it is logically necessary that the applications should be so given that the whole body should be brought under the direct influence of the current, just as it is brought under the influence of other recognized tonics as ordinarily administered.
The immediate effects of an application of general faradization, central galvanization, or static electricity, are often a feeling of enlivenment and exhilaration, drowsiness, temporary relief of pain, and increased warmth
200 ELECTRO-THERAPEUTICS.
of the body. The same effects are notably observed after the shower bath, a tumble in the surf, a brisk walk in the open air, or from the administration of alcohol.
Like other stimulating tonics, general faradization, central galvanization, and franklinization, when given in an overdose or in too great strength for the constitution of the patient or the condition of the system at the time, may be followed by secondary or reactive effects that are both disagreeable and positively alarming. The second or third day after an injudicious application, very sensitive patients, especially at the outset of treatment, may experience soreness in the muscles, an indefinable feeling of nervous exhaustion, irregularity of pulse, and sometimes exacerbation of special symptoms. It is well known that severe physical exercise will produce all these unpleasant secondary effects, especially in patients who are feeble and unaccustomed to muscular exertion. A cold bath, either in the surf or at home, that is too prolonged may give rise to all these symptoms the night or day following. Unpleasant effects may secondarily follow an overdose of our ordinary stimulants, as alcohol, or from internal tonics, as iron, quinine, strychnine.
The permanent effects of these general methods of treatment are as closely analogous to those which come from other tonic remedies and systems of treatment as are the immediate and secondary effects.
The very marked permanent effect of general faradization, central galvanization, and general franklinization is improvement in the sleep. Physical exercise -- walking, boating, gymnastics, bowling -- cold bathing, and the ordinary internal tonics do the same, though not so markedly and with far less uniformity.
These methods also permanently improve the appetite and digestive capacity, and regulate the bowels. Improvement in the various operations of digestion is one of the most uniform effects of our ordinary tonics, and it is for that purpose, more perhaps than for any other, that they are employed.
Like other tonics, general faradization and central galvanization equalize the circulation. This effect, when it immediately follows an application, is merely the temporary excitement, similar to what follows a rapid walk, or gymnastics, or alcoholic stimulants, and soon passes away. But when it becomes a permanent condition -- when the patient feels less annoyance from chilliness and cold extremities -- it is a resultant of the improvement in nutrition. |
When these distinctions are kept in view, the practice is easy. The discharge of blood is either an active or a passive haemorrhage, generally passive, and in neither case highly dangerous. Indeed we have seen very considerable discharges of Wood by stool, from strains in the young and active, yield to nitre, to opiates with occasional mild laxatives. The passive haemorrhages require astringents, with the vitriolic acid. Thebloorl in these cases flows from different arteries, and its source requires no variation of practice.
When the bile is dark, a previous suppression has usually occurred ; and the discharge, which is essentially necessary, must be regulated by the strength of the patient. The pitch-like bile, or perhaps the grumous blood, requires also to be evacuated ; and the best medicine for each purpose, if the strength of the patient will admit, is calomel. This medicine, were we to revive the term, we should style the true cholagogue. But the pitchy and the flaky bile, in worn-out constitu-
tions, must be gradually discharged, and the strength supported by wine, by nourishing diet, by aromatics, and by any thing but astringents.
Pains are uncommon; and if they occur, must be obviated by fomentations, and by opiates. They are truly spasmodic, for inflammatory pains only attend inflammation of the membranes of the liver.
Thte discharge from piles sometimes resembles the melaena ; but the pain, at the lower part of the rectum, the fulness and tension, sufficiently distinguish them.
See Hippocrates, lib. ii. De Morbis, sect. v. ; Hoffman, Rationalis Medicina Systema; Edinburgh Medical Commentaries, vol. iv. ; London Medical Journal, vol. i. p. 10.
MORDE'HI. A disease to which the East Indians are subject. It is a fever seemingly from bile in the stomach. See F. Hoffman, De Morb. Epidemicis.
MORDE'XYN. A disorder very common at Goa, which seizes the patient suddenly, attended with a continual nausea and vomiting, and often proves fatal. F. Hoffman, De Morbis Epidemicis.
MORHU'A. See ASELLUS MAJOR.
MORI'LLE. See AMANITA.
MORI'NA. A plant, named in honour of Dr. Morin of Paris. Marina fiersica Lin. Sp. PI. 39, said to be cordial and perspirativc.
MORI'NGA. Guillandina morin^a Lin. Sp. PI. 546. A large tree in Malabar and Ceylon, whose fruit is a foot long, angular, as thick as a carrot, and delicious to the taste. The leaves, root, bark, and fruit, are said to be antispasmodic and sudorific. See Raii Historia.
MO'RO (from morns, a mulberry}. An abscess in the flesh, resembling a mulberry.
MOROCTHUS. See OMOROCTHUS.
MORO'SIS, (from ftw^s, foolish}. STUPIDITY, IDIOTISM. This may be styled a mental disease, sometimes owing to a more slow expansion of the mental faculties, which often, however, attain their powers suddenly, and in perfection, as suppressed irritability is followed by excess of excitement. When the mental powers are developed slowly, we often find a defective conformation of the cranium, and particularly an elongation of the upper part, while the sides are unusually depressed. Pinel, who scarcely admitted any organic defect to produce mania, admits it as a cause of idiotism. When in a less degree, it is not connected with any defective organization which the knife can discover.
Dr. Cullen considers this disease as synonymous with AMENTIA. Sauvages makes it a species of AMENTIA, and defines it a slowness or inability in the faculty of imagining or conceiving; consequently a debility in judgment without delirium. Stupidity differs from folly, as stupid or idiotic persons want both conception and memory. See AMENTIA. |
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of electricity 188 Exr. 174. Wich the condensers 47 -- 175. Wich an electrophorous 3 193 -- 176 to 178. Wich condensers | 194
-- 179. Io illustrate part of the theory 200
E HAT. ME
Of atmospherical electriciti 205 Beccaria's apparatus | 206 Effects of moisture in the air 5 | 208 Sign of the weather's clearing up „ Fogs electrical 3 | 210 Diurnal atmospherical eleQricity 213 Electricity of evening der e Exe. 180. To usfrate the dectricity of dew 210 Observations on a kite for electricity and its appa- | ratus 217 Phial to preserve a charge | 220 Electrometer for the atmosphere n 220 Ditto for rain 5 3 Portable atmospherical electrometer 223 General laws deduced from the experiments with the kite 225 | Mr.
N Joni >
LOR
dd
tr ae
I --
a. --
ti icity Exp. 181.
Water
Wax
Page Mr. Achard on ele&ti cal . 228 1 of his atmospherical electrometer 235 CHAP. x On the diffusion and subdivision ve fluids by elec- With a capillary pipe | 244 -- 182. With two capillary pipes on b electrified with the different powers 245 -- 183. Luminous stream of water 24 Fiery rain why | A pail with several . tubes 246 Drop of water attracted, &. 246 Battery discharged chrough a drop of | | F Ky 247 With a drop of water 247 Long spark with water | 248 Fine hlaments procured from sealing
192. Electrified jet d' eaux 249
Kanne
CHAP.
Of che electric light in vacuo
XIV;
Exe. 193. With a tall receiver 250 An observation of Mr. Wilson 2:1 Exp. 194. Ta shew that electricity is not repulsive of itself 251 ---- 195, 196. EleQric appearances in vacuo 253 -- 197. Flask to imitate an aurora borealis 254 ---- 198, Leyden phial in vacuo 254 -- 199. Double barometer 255 -- 200. Green spatks in vacuo 25 CHAP,
cow rTENTS.
Page Of medical ufig wy ogy ns Considerations on the importance and universal 258 agency of electricity | 3 Exp. 201. On a mouse 24,24 2 -- 202. Shock through different parts of the © human bod | | 15 266 -- 203 LleQricity put in action by heat and cold | 269 ---- 204. Thermometer raised by electricity © 270 Medical apparatus and its use 273
CHAP. NXVL
Miscellaneous experiments and obseryations
Exp. 205. Made at the pantheon 282 2 207. To fire gun-powder 284
Pyramid described | 285 Exr. 208. With camphor on fire 280
-- 209. Cotton fired | 286
Mr. Volta's inflammable air lamp described . 286
ExP, 20. With Mr. Kinnersley's thermometer 288
-- 211, Oil of tartar chrystalized *' 289
-- 212. Long spark | 290
21 to 215, On phosphorous 2090
-- 216, By Mr. Achard | 293
-- 217. Jo perforate a glass tube 297
-- 218. Magic picture 299 -- 210. With brass dust | £5." 26" ; -- 220, On smoke | CSS 4 300
-- 221. The luminous chain * ooo
-- 222. The luminous discharger 7-25 $00
-- 223. The luminous tubes est 302
-- 224. The circulating ball | 303
Mr. Brooke's electrometer described 304
Exp. 225. Colour of vegetable jusce; changed ob Experiments on different elastic fluids | :
xvi SET EE MD $ Ss RS bak Page
Of the analogy between heat and eleQricity by Mr. E 317
An ESSAN on MAGNETIS M.
In which the properties of the magnet are illustrated
dy a variety of curious experiments. ne TIF EN Ol
| , TY k 7 2
J g * : Fo * > L | by . : | Im "ns
* 4 . a . pe a ; 2 ,
” = the * q bg n CY 3 , Wen 4
Page 48, I. 9, readhIK. - 4g, I. 11, for which, read and, 69, I. 3, read Hauxsbee. 69, 1. 8, Ditto, N 7, 1. 17, for fixed, read fired. 1 ERS 129, I. 3, for disploded, read exploded, 2 244, 1. 26, for phial, read pail. 2 287, 1. 27, after the reservoir A dele a. 304, 1.-13; read the ball in I. | | 304, I. 15, for fig. 69, read 96. 316, 1. 14, for needle, read needles, 325, I. 6, for fig. 98, read 106.
CONN KURT an OI
o N
ELECTRICITY.
F 4 Alt -- -- ** _ "ITY _-- _ - WE I" _ pr
HAF of g in re 1
T must appear surprising to every 1 aster truth, that Electricity, which is now F to be one of the principal agents. employed in producing the phoenomena of
nature, should have remained so long in obscu- |
Chief Cities-- Census of 1890.-- Des Moines, metropobs and capital, pop. 50,067 ;Dubuque,30,147 :Davenport,25,161 ; Burling ton,26,000:Council Bluffs 3,21,388. Keokuk, Burlington and Du¬ buque are United States ports of delivery. Cedar Rapids. 17,- 977; Clinton, 14,000; Davenport, 25,161; Keokuk, 14,075; Sioux City, 37,862.
Leading Industries.-- Agriculture, stock-raising and manu¬ facturing. -
[Salaries of State Officers, page 439.]
KANSAS.
Name Indian, means “Smoky water.” Called the “Garden State.” Kansas Territory organized May, 1854. Law known as “Missouri Compromise,” forbidding slavery in states formed outof Lonisiana purchase north of latitude 36 deg. 30 min. re¬ pealed, and question of slavery left to the territory. At first it was decided for slavery. Constitution prohibiting slavery adopted July, 1859. Admitted asa state 1881. Union soldiers fur¬ nished, 20. 149, number counties 95, miles railroad 8,810, first rail¬ road built 1864, 40 miles long. All elections Tuesday after first Monday in Nov. senators 40, representatives 125, sessions bien¬ nial, meeting second Tuesday in Jan. in odd-numbered years, limit of session 50 days; term of senators 4 years, of represent¬ atives 2 vears. Number electoral votes 9,congressman 7. Idiots, insane, convicts and rebels excluded from voting. Number col¬ leges 8, number scboolhouses over 8,000, school age 5-21 years ; school system magnificent.Endowment immense. Legal interest
7 per cent, by contract 12 per cent, usury forfeits excess of inter¬ est.
Population. -- Cens is of 1890, 1,427,096.
Extreme length E. and W., 410 miles, breadth 210 miles, area 81,700 sq. miles, 52, 288, (XX) acres. No mountains. There is little navigable water. Water powers of fair proportion, irrigation necessarv in large sections. Coal area of moderate extent ; veins usually thin; quality fair. Soil fine. Corn, wheat, oats, hemp, fiax and rye, staples. Castor beans and cotton "rows success¬ fully. Soil of prairies deep loam of dark color ; bottoms sandy loam. Peculiarly favorable to stock-raising. Prairie rich in grasses. Dairying favored. Fruits successful. Fbrests small. Limestone and colored chalk furnish building materials. Value improved land averages $12 per acre, woodland $15. Manufactur¬ ing growing. State ranks fifth in cattle, corn and rye. Climate-- Salubrious; winters mild, summers warm, air pure and clear. Temperature averages winter 31 deg., summer 78 deg., ranges
8 deg. below to 101 deg.above zero; such extremes exceptional. Rainfall averages 45 inches at east, 33 inches at we6t.
Chief Cities-- Census of 1890.-- Leavenworth, pop.21,613, To¬ peka (capital) 31. 809, Atchison 14, 222, Fort Scott, 11,837; Wichita 24,000, Lawrence 9,975. State University at Lawrence, state asy¬ lums for insane and feeble-minded at Topeka and Ossawatomie; institution for education of the blind at Wyandotte, for deaf mutes. Olathe.
Industries.-- Agriculture, stock-raising. manufacturing, etc.
SALARIES OF STATE OFFICERS.
Governor $3,000, Secretary of State $2,000, Treasurer $2,500, Auditor $2,000, Attorney General $1,500, Superintendent of Pub¬ lic Inst. $2,000, Secretary Board of Agriculture $2,000. Insur¬ ance Commissioner $2,500, three Railroad Commissioners $3,000, State Librarian $1,500, Chief Justice $3,000, two Associate Justices $3,000, Senators and Representatives $3 per day, mile¬ age 15 cents, District Judge $3,500, Pension Agent $4,000.
ui
LOUISIANA. |
93. Engines rarely receive heat from various sources in the way supposed, and the great importance of the result arises from the fact that it is immaterial from whence the heat is derived, provided that the fluid receives heat at the temperatures supposed. For example, in the perfect steam engine of Art. 62, the heat is derived from the hot gases of the furnace at a temperature much higher than that of the boiler : yet, in considering the efficiency of the engine, it is the temperature of the boiler which is considered, not that of the furnace, because it is at the temperature of the boiler that the fluid receives heat.
Thus the results are applicable to any engine whatever, receiving heat at any temperatures, provided only that the whole expansive energy of the fluid is completely utilised. Subject to this proviso, the following general statements may be made, which are equivalent to the foregoing equations.
FIRST. -- The efficiency of every possible heat engine depends solely on the mode in which it is supplied with heat, and not at all on the nature of the fluid or arrangement of the engine.
This principle is the last step of a gradual generalisation, of which the principle laid down in Art. 27, Chapter III., and Carnot's principle explained in Art. 55, Chapter V., are special cases. In Chapter III. it was shown that it is a necessary consequence of the principle of work, that the energy exerted by a given quantity of a given kind of fluid, is independent of the particular kind of machinery by means of which that energy is utilised. In Chapter V. we found that although the magnitude of the energy exerted varies according to the nature of the fluid, yet, when it receives and rejects heat at given fixed temperatures, the proportion which that energy bears to the heat expended, that is to say, the efficiency of the engine, is the
208 PERFECT ENGINES. [On. VII.
same for all fluids, and consequently for all possible engines. Now we go a step farther, and assert that this will be the case, not only when the engine receives heat at one fixed temperature and rejects heat at another fixed temperature, but also when it receives heat at any number of temperatures, provided only that the quantities of heat received at the various temperatures are in the same proportion.
Thus, if the law according to which heat is supplied be supposed given, an engine will be of maximum efficiency, and hence may be said, in a certain sense, to be "perfect," even though it receives heat at varying temperature from a source the temperature of which is much higher, the only condition of maximum efficiency being that there shall be no unbalanced expansion. With a single source of fixed temperature, that temperature is the true datum of the problem, and then it is only engines which receive the whole of their heat at that temperature which can be considered as " perfect " in the full sense of the word : all others are of less efficiency, because they receive some of their heat at a lower temperature.
We have supposed for simplicity, as being sufficiently general for the purpose, that the heat is all rejected at a single temperature, but this restriction is not necessary for the truth of the reasoning employed.
SECONDLY. -- If the heat received at any temperature by a heat engine be divided by that temperature (absolute), the sum of the quotients is unaltered by the passage of the heat through the engine.
This principle is merely the expression in words of equation (B), and amounts to saying, that although heat disappears (being changed into work), during its passage through a heat engine, yet that a certain quantity, found by dividing the heat by the temperature at which it is used, is unchanged, if the opportunity of turning heat into work, presented by the available difference of temperature, has been duly utilised. |
If one of these strings, both of equal tension and diameter, but of different lengths, be struck, the other uill vibrate with it in aliquot parts, the points of division between the parts remaining quiescent; as is evident to the sight, by pieces of paper remaining at rest on these points, while similar pieces laid on any other points will be shaken off by the vibrations. If one string be twice as long as the other, it will vibrate by halves, the middlc'point remaining quiescent; and if three times as lot^, there will bu tno points at rest, while the string is vibrating in the three different lengths of it. The reason is, because the same vibrations of the shorter string are communicated to the contiguous air, and by the air to the quiescent string, which, being of equal tension and diameter, cannot vibrate in unison with the shorter, or ivith the contiguous air, in any other manner, than by vibrating in lengths, each being equal to the length of the shorter string. And hence, wc see the reason of the construction of the double- stringed violin, whose untouched strings vibrate in unison with the others, and thereby greatly heighten the melody and harmony of the music.
Hence, also, if V and L be given, T Is proportional to D; that is, if the tending force and lengths of two strings be the same, but their diameters different, the dmes of their vibrations will be as their diameters. If the diameters be as 2 : 1, the string, whose diameter is greatest, will vibiTtte slowest in the same proportion,
and their coincidence ^vill be at cveiy second vibradon of the least; and they will therefore sound an octave.
Lastly, if D and L be given, T will be as v'F; Aat is, if the diameters and lengths of two strings be the same, the times of their vibrations will be asdiesquve roots of the tending forces, inversely.
Now, as the tone of a string depends entirely on tlie time of the \ibration, it is easy to understand, that whoever the sounding body be, or how many soever ibtit may be of them, if they perform the same number of vibrations in the same time, they will all sound the same note and be in nnison. And if the vibrations be perfonncd in unequal times, the coincidence will be after certrin inter\'als, and the shorter that these intervals arc, so mticb the more agreeable is the consonance to the ear. Hence, when one string vibrates twice, while the other vibtalts once, the coincidence will be most frequent, and ihcirfore it is called ihe most perfect concord, as it is nuM agreeable to the car. \V'hen the times of their vibration are as two to three, tlie coincidence ^vill be at evay third of the quickest, and therefore, this, which is caSrt a fifth, is in the next degree of perfection.
Thei'e are but seven whole notes or tones in & scale; for when you come to the eighth, it is no Ddta* than the octave to the first, and the octa\e above and below is only a replication of the same sound. And i skilful artist, in the construction of musical insCrunKfl>t will compound the various proportions of length, dttmeter, and tension of strings, in such a manner 4»to |iroduce the most agreeable consonance to the ear.
If, instead of strings of the same diameter and tension, but different in lengths, one string be taken mi stopped at different places while it is vibrating, it give dififerent sounds, according to the
H 251
^Ultog thai IS suffered to vibrate without intciTUptlun.
P40ie whotf lentil of the string, wliatever that iiuiy be,
I lis called the monochord, and the sound produced by it
I JE called tlie key-note. If bull" tht string be suffered to
vibi'atc, tlie sound produced is culled the octave to the
first note or sound; because musicians have particularly
six different sounds distinguished between them, which
.■ire excited by stopping the string iit certain places be.
twcen these two points, while the remainder is suffered
to vibrate. The proportion of length for making diese
sounds will be assigned presently. |
Another science which has not yet recovered from the unmerited contumely into which it had fallen, owing to its having been employed by itinerant pretenders for the purpose of drawing a crowd and amusing the thoughtless multitude for an hour, is Phrenology ; but a day will surely come when its merits will be acknowledged ; for, whatever may be alleged to the contrary, it is the only means we possess of forming an estimate of the innate mental and moral tendencies of man.
Electricity ,
Mr. Donovan, the late distinguished phrenologist of London, England, to whose kind instructions I am deeply indebted for much of my success as a consulting physician in constitutional diseases, carried the science a step further, and after many years of careful investigation, clearly proved that not only the mental and moral, but also the physical constitution of man might be determined by the conformation of the head, and the few medical men who have become conversant with the subject have borne testimony to its value in the treatment of disease ; as by the aid of phrenological diagnosis we are enabled at once to determine the original constitutional condition of a patient’s stomach , heart and lungs, and form a correct estimate respecting the amount of general vitality which he possesses.
When the merits of Phrenology shall be fully recognized, parents will take their children to well-qualified men and obtain their advice as to the employment for which they are mentally adapted, and then we shall not meet with so many men of undoubted talent whose lives have proved failures, owing to their having been educated to trades or professions for which they had neither the mental nor physical qualifications.
The study of Phrenology will then be considered as
Nature's Tonic.
indispensable a part of the education of a teacher as anatomy and physiology are now held to be with the medical student.
And, in like manner, when “ Constitutional Phrenology,” if I may so call it, has established its claims, parents will be glad to avail themselves of the advice of competent men as to the course of life to be pursued by their offspring in order to eradicate constitutional defects from their systems.
But to return to the subject of Electricity, its study and successful application must ever require time and attention. Many uneducated persons labor under the delusion that in order to test its value in any disease, it is merely necessary to obtain a battery, no matter what kind, hold the two handles, causing a current to pass through the arms and “ take a shock!' This is one of the mistaken notions which have brought Electricity into disrepute. What sensible person would imagine, that in order to cut out and fit a garment it were only necessary to purchase a pair of scissors and cut away at the cloth ?
In order to understand how it is that Electricity acts so beneficially in Chronic Diseases, by which we understand Diseases of long standing , it will be necessary to explain how diseases become chronic or lingering.
Electricity ,
Let us suppose that two individuals are overtaken in a storm, get thoroughly drenched and have to remain for some time in their wet garments. The result would in all probability be what is commonly termed “ a cold.” But while in the one person the effects might be thrown off in a few days and health completely restored, in the other they might hang on for months, settling in the joints in the form of Rheumatism, or perhaps on the lungs in the form of Consumption. |
Ax» again our ungeometrical Philosophers may object, That there is not rated n plane Superficies, a Body perfectly spheri | Geometers feign, nor any Curve But how come they to all this? scen all the Bodies that are in the. Universe, and vie w'd them thro? a Microscope? Perhaps they will say, that a Superficies cannot be plane or spheri - because in these Figures there is a Contradiction and an Im ility. But we desire they would be pleased ro make out this Contradiction: All Bodies of necessity are terminated by some Figure, plane or spherical Surfaces are the most simple and easiest to be conceived of any; where then lies the 5 that it should be impossible for a Body to be conrained under these Surfaces? I believe there is no one who is acquainted with the Elements of Geometry, but perceives more the Nature and Properties of these Figures, and knows more of their Affections, than all the Philosophers of this fort put together : but none of those ever found any R these Figures; no Geometer ever suf
pected these Contradictions in the Nature of Figures: on the contrary, so many beautiful Properties of those Fi- gures discovered and demonstrated by the Geometers, evince their - Possibility, for of an impossible thing there can be no real Property, no Demonstration. | that they acknowledge these and if they are ble, it is in " of Matter, Bodies therefore suppose two
F_="y
Led. 3- Natural Philosophy.
ewo Bodies, whereof one is terminated by Planes, the other by a be Plane, ir wil spherical Superficies 1s placed on the it touch it; but it will touch it only in one, and that an indivisible Point, or in a Point that has no Parts, by Cor. Prop. 2. El. 3. and therefore in that case there ll deajoms © wee Pele. But farther, let us suppose this spherical Body to be moved on the plane Superficies, or to be carried along without any Rotation about its Axis, insomuch that the Point touching the plane may be always found in the same Plane; then the Traft which that Point describes by its motion, will be a Mathematical Line, without any Breadth: and if the Distance betwixr
Lines, or partly of these; and partly of those, will be described. FR therefore, Lines,
ways; but we are ing
fles. We shall only farther observe, that the Distance betwixt any two Points of two Bodies, will be their given and determinate Distance: As, for example, the determinate Distance betwixt the Centers of the Sun and a fixed Star, is that which is measured by right Line hing berwix those two Fun: which,
26 An Introduttion to
the Line will remain the same in Magnitude and Position, as long as the Centers of the Bodies remain unmoved.
H aving now settled these Principles, we return to our Purpose ; which was to demonstrate that all Extension, whether corporeal or incorporeal, was divisible in infinitum, or had an infinite Number of Parts; which we shall endeavour to prove by many invincible Arguments. Of which, this shall be the first: Let AB represent a right Line, I say it is divisible into Parts exceeding any finite W what-
BE
F G Turoven A let be and parallel to it let be Line BD, and in AC as C: if therefore the right Line AB is not divisible into an infinite Number of Parts, let it be divisible only into a finite Number of Parts; and let that Number, for example, be fix. In the Line BD on the side opposite to C, let there be taken any Num- a ber of Points exceeding fix; for Example, the Points E, F, G, H, I, K, L, and let there be drawn by the first Postulate of Euclid, CE, CF, CG, CH, CI, _ CK, CL. These thus drawn, divitle the right Line A B into as many Parts as there are right Lines; for if they do not, then some of the right sect AB in one and the same Point: intersect one another-in the common
\y. } ty
LeR. 3. Natural Pbilosophy. 27 |
of the fan, the discharge-pipe being placed at that part of the circumference of the case where the eccentricity is the greatest ; the air being admitted at the centre in the same manner as before stated. In this form there is comparatively little loss of power ; but owing to the inertia of the air, some loss must always occur between the calculated and the actual discharge, the difference being always greater in proportion to the greater speed with which the fan revolves.
(364.) The mode of calculating the quantity of air discharged by any mechanical method, as also the power expended in discharging it, is necessary to be known, in order to apportion an apparatus of a proper size to any particular building. Both these subjects have been investigated by Dr. Ure,* who has made various experiments connected with this branch of inquiry. The mean velocity of the portion of the vanes of the fan by which the air is discharged is about seven-eighths of the velocity of the extremities of the leaves; but, owing to the inertia of the air, there will be a further loss in the velocity of the issuing current, increasing with the greater velocity of the vanes ; so that, under ordinary circumstances, the current will be discharged with a velocity equal to about three-fourths of the velocity of the extremities of the leaves. This velocity, in feet per second multiplied by the area of the discharge-pipe in square feet, will give the number of cubic feet of air discharged per second. To estimate the force necessary to cause the rotation of the fan, the following method of calculation, founded on the ordinary mode of estimating steam
* Philosophical Transactions, 1836. See also Peclet, " Traite de la Chaleur," 3rd edition, p. 100 et seq., for some useful calculations on the relative cost of various methods of discharging air for ventilating purposes. Also Wyman "On Ventilation," p. 169.
OP PRODUCING VENTILATION. 375
power, will be found sufficiently accurate. Suppose the effective velocity of the vanes of the fan to be 70 feet per second, and the sectional area of the eduction tube to be 3 square feet, then 70 x 3 = 210 cubic feet will be the quantity of air discharged per second ; and this number, multiplied by 60, will give the quantity per minute. As a cubic foot of air weighs 527 grains, there will be about 13 cubic feet of air to a pound ; therefore ^^-° = 969 Ibs. is the weight of air put in motion per minute with a velocity of 70 feet per second. The height from which a gravitating body must fall in order to acquire a velocity of 70 feet per second is ^ = 76*5 feet, which, multiplied by the number of pounds weight moved per minute, will give the power necessary to be expended in order to discharge this quantity of air at the stated velocity; and this product divided by 33,000 (the number of pounds weight that one horse will raise one foot high per minute) will give the amount of steam power required. Therefore ^^ = 2 • 24, or nearly 2i horses' power, will be necessary to discharge the given quantity of air at the. velocity stated.
The quantity of air discharged by bellows is easily calculated. The cubic contents of the box (or that portion of it which is filled and emptied at each alternation of the handle), multiplied by the number of strokes per minute, will, of course, give the quantity of air discharged ; making such deduction from this amount as may be necessary for imperfect fitting of the diaphragm. The ventilating pump differs from the bellows simply iii making the whole diaphragm move up and down, instead of one end being fixed. The force requisite for discharging the same quantity of air by either of these methods is the same as with a fan. For, suppose a ventilating pump three feet
376 ON THE VARIOUS METHODS |
of that Prince, had no Suspicion, that what was his Part of the Picture, was not done by himself, and had thought it his
own doing as long as he liv'd, if Vasari, who had icen the Copy while it was Drawing, had not disabus'd him; for
coming to Mantua, he was mighty well cc
entertain'd by Julio Romano, who shew'd him all the Duke's Rarities, saying, That
the fine. Thing was fill to be seen, naming the Picture of Leo X. done by Raphael, and shewing it him, Vasari « laid, 716 very fine, but tis not Raphael's,
cc.
Julio Romano looking on it more atten-
tively, reply'd, How is it not Raphael's?
Don't I know my own Work in it? Dont 1 jee the Strokes of my Pencil, and re-
« member the ftriking them? Vasari ancc
od
twer'd, Zou don't observe it closely
enough ; I afsure you, I saw Andrea del
Sarto draw this very Pifture Behind
* the
of PAINTING. 361
« the Canvas you'll see a Mark which was e put upon it to diftinguish it from the Ori- By Fulio Romano Ne about the icture, and perceiving it was Matter of
act, held up his Hands with Astonish-
„ment, saying, I value it as much as if
« it was Raphael's, and even more; for
« ?z5 Very 7. ri sing to see /o excellent Aa
c Mafer /o Wel imitated as to decerve .<. ons;” *
Now if Julio Romano with all his Art could thas mistake a Copy for an Original, which was partly his own Drawing, it can't
be suppos'd that such a Critical Skill in
Painting is easily acquired by every one. However, it does not follow from hence, but that other Gentlemen, besides those of the Profession, may have a Notion of Painiing, and be, able to know a good Picture, wheneyer they see it: It is poslible for a
Man of Sense to enter into the most mate-
rial Beauties of an Epic Poem without being able to write one. And by reading the most eminent Authors upon Painting, by seeing good Collections of Pictures, and ob-
serving the peculiar Manner of the best
Masters, Gentlemen of a tolerable Taste, tis well known, have become good Judges of Painting, and been able to discover the
| Beauties of the finest Pieces. I shall only
therefore beg Leave to recommend such Au- thors to the young Gentleman as are generally
= Mons, de Piles's Art of PAINTING, Pages 72, 3 A A 4 thoug ht
.. -- M rl A nl oC ener
362 Of PAINTING. thought to be the most curious upon the
Subject, and conclude my Oblervations up-
on Painting. The best Treatises 1 have seen of this kind, are the following.
1. The Art of Painting by Monsieur de Piles.
2. The last Edition of C. A. du Fresioy 8 Art of Painting by Mr. Graham.
3. An Essay on the Theory of an 8
by Mr. Richardson.
4. Roma Ilufrata.
These Authors are like good Critics upon the Clasics. Their Design is to give Gentlemen a true Taste of Painting, by pointbs. to the peculiar Manner, the distinguishing Excellencies of the best Masters, by dis-
playing the essential Principles of the Art in general, and shew ing the Pelicacy, the
Force and Beauty of fine Pieces in particular. .
Monsieur de Piles's Treatise was writ on Purpose to assist the Taste of the Curious,
and enable them to form a Judgment of the Works of Paiuters. To this End he
frist gives us the Idea of a perfect Painter,
by pointing to those Qualifications that con-
stitute his Character, and by explaining such Particulars as are necessary to give
Beauty and Perfection to a Picture: To these excellent Remarks is added à short
Account of some of the most eminent Mafers, Ancient and Modern, where the
most
as an = *fay
Of PAINTING. 363 most remarkable Incidents of their Lives are taken Notice of, and their peculiar Style and Expression. delcribed with great Skill and Exactness.
Monsieur du Fresnoy's Poetical: Performance, when first publish'd, was look'd upen to contain as good Directions for Painting,
as any thing that was then extant 870 the
kind. „This Author was recommended to Mr. « Dryden, who translated him, as one who
* perfectly understood the Rules of Paint- |
34 9. We shall see that the fusee is a, complete remedy for the varying action of the main-spring. Its form is a low cone, with its surface cut into a spiral groove, to receive the chain, which runs round the barrel. Now when the watch is wound up, by applying the key to the axis of the fusee at C, the mainspring, one end of which is attached to the diameter of the barrel, and the other to its axis, is closely coiled ; but as the action begins on the smallest part of the fusee, the leverage is short, and the power weak ; but as the fusee turns, and the spring uncoils, the leverage increases in proportion as the strength of the spring becomes weaker, and thus the two forces mutually equalize each other, and the watch runs at the same rate until the chain which connects them has run from the barrel to the fusee, when it again requires winding, and the same process begins again.
350. System of Wheels. -- As the wheel and axle is only a modification of the simple lever, so a system of wheels acting on each other, and transmitting the power to the resistance, is only another form of the compound lever.
351. Such a combination is shown in Fig. 70. nG - 79 - The first wheel, A, by B means of the teeth, or cogs, around its axle, moves the second wheel, B, with a force equal to that of a lever, the long arm of which extends from the center to the circumference of the wheel, where the power P is suspended, and the short arm from the same center to the ends of
the cogs. The dotted line system # WherU.
C, passing through the center of the wheel A, shows the position of the lever, as the wheel now stands. The center on which the wheel and axle turns, is the fulcrum of this lever. As the wheel turns, the short arm
349. How does the fusee equalize this force ? Explain how the forces of the sprint and fusee mutually equalize each other. 350. On what principle does a system of wheels act, as represented in Fig. 70? 351. Explain Fig. 70, and show how the power F is transferred by the action of levers 1
86 WHEEL AND AXLE.
of this lever will act upon the long arm of the next lever by means of the teeth on the circumference of the wheel B, and this again through the teeth on the axle of B, will transmit its force to the circumference of the wheel D, and so by the short arm of the third lever to the weight W. As the power or small weight fells, therefore, the resistance W, is raised, with the multiplied force of three levers acting on each other.
852. In respect to the force to be gained by such a machine, suppose the number of teeth on the axle of the wheel A to be six times less than the number of those on the circumference of the wheel B, then B would only turn round once, while A turns six times. And, in like manner, if the number of teeth on the circumference of D, be six times greater than those on the axle of B, then I> would turn once, while B is turned six times. Thus six revolutions of A would make B revolve once, and six revolutions of B would make D revolve once. Therefore, A makes thirty-six revolutions while D makes only one.
853. The diameter of the wheel A, being three times the diameter of the axle of the wheel D, and its velocity of motion ! being 86 to 1, 3 times 36 will give the weight which a power of 1 pound at P would raise at W. Thus 36 X 3 = 108. One pound at P wou|d therefore balance 108 pounds at W.
354. No Machine Creates Force. -- If the student has attended closely to what has been said on mechanics, he will now be prepared to understand, that no machine, however simple or complex, can create the least degree of force. It is true, that one man with a machine may apply a force which a hundred could not exert with their hands, but then it would take him a hundred times as long. |
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