UNIVERSITY OF CALIFORNIA.
RAMSDEH'S ELECTRICAL MACHINE.
DIONYSIUS LARDNER, D.C.L.
PROFESSOR OF NATURAL PHILOSOPHY AND ASTRONOMY IN UNIVERSITY COLLEGE, LONDON,
ELECTRICITY, MAGNETISM, AND ACOUSTICS.
GEORGE CAREY FOSTER, B.A., F.C.S.
FELLOW OF, AND PROFESSOR OF PHYSICS IN, UNIVERSITY COLLEGE, LONDON.
WITH FOUR HUNDRED ILLUSTRATIONS.
BOOKSELLER AND PUBLISHER TO UNIVERSITY COLLEGE,
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ADVERTISEMENT TO THE NEW EDITION.
THE extensive circulation which Lardner's HANDBOOK OP
NATURAL PHILOSOPHY has met with ever since its first
publication, and the large demand for it which still exists,
prove conclusively that it supplies the requirements of a
large number of students of Elementary Physics. Hence,
in preparing a New Edition of the volume which treats of
Electricity, Magnetism, and Acoustics, the Editor, while
endeavouring to bring it into harmony with the best scien-
tific teaching of the day, has adhered as closely as possible,
not only to the arrangement and general plan, but also
to the phraseology of the last edition published in the
The changes which it has been thought desirable to
make have naturally been, in part, by way of addition, and,
in part, by way of substitution and alteration. Among
the more important additions to Book I. are a Section on
the phenomenon of the residual charge of the Leyden
jar, and a Chapter (XIV.) on Sources of Electricity other
than friction. The principal additions to Book II. relate
to Ohm's law of the intensity of currents, the tangent-
galvanometer, the measurement of conducting powers, the
rheostat, ozone, the polarisation of electrodes, the retarda-
tion of telegraphic signals by inductive action in sub-
marine cables, and the laws of the development of heat
in the voltaic circuit. In the same Book, in addition to
numerous smaller alterations, Chapter I. has been almost
entirely rewritten, as well as large parts of Chapters III.
and IV. and several Sections of Chapter XIII. The
changes in Books III. and IV. are less extensive, the
most considerable being in Section 647, on the velocity
of sound, in Sections 675 and 676, on the extremes of
high and low pitch, and in Section 694, on the theory
In all cases where the new matter inserted by the present
Editor amounts to one or more whole paragraphs, it is
distinguished by being enclosed between square brackets
[ ] ; but smaller alterations and corrections are not thus
marked, except in a few cases where a slight change of
language produces an important change of meaning.
10th April, 1866.
THIS work is intended for all who desire to attain an accu-
rate knowledge of Physical Science, without the profound
methods of Mathematical investigation. Hence the expla-
nations ar6 studiously popular, and everywhere accompanied
by diversified elucidations and examples, derived from
common objects, wherein the principles are applied to the
purposes of practical life.
It has been the Author's especial aim to supply a manual
of such physical knowledge as is required by the Medical
and Law Students, the Engineer, the Artisan, the superior
classes in Schools, and those who, before commencing a
course of Mathematical Studies, may wish to take the
widest and most commanding survey of the field of inquiry
upon which they are about to enter.
Great pains have been taken to render the work complete
in all respects, and co-extensive with the actual state of the
Sciences, according to the latest discoveries.
Although the principles are here, in the main, developed
and demonstrated in ordinary and popular language, mathe-
matical symbols are occasionally used to express results
more clearly and concisely. These, however, are never
employed without previous explanation.
The present edition has been augmented by the introduc-
tion of a vast number of illustrations of the application
of the various branches of Physics to the Industrial Arts,
and to the practical business of life- Many hundred en-
gravings have also teen added to those, already numerous,
of the former edition.
For the convenience of the reader the series has been
divided into Four Treatises, which may be obtained sepa-
MECHANICS .... One Volume.
HYDROSTATICS, PNEUMATICS, and HEAT . One Volume.
OPTICS ..... One Volume.
ELECTRICITY, MAGNETISM, and ACOUSTICS . One Volume.
The Four Volumes taken together form a complete
course of Natural Philosophy, sufficient not only for the
highest degree of School education, but for that numerous
class of University Students who, without aspiring to the
attainment of Academic honours, desire to acquire that
general knowledge of these Sciences which is necessary
to entitle them to graduate, and, in the present state of
society, is expected in all well educated persons.
ELECTRICAL ATTRACTIONS AND REPUL-
I. Electrical effects l
Origin of name of electricity - z
z. Positive and n> gative electricity - 3
3. Nature of electricity ... H>.
4. Mode of describing electrical effects ib.
5. Hypothesis of <i single electric fluid 4
6. Hypothesis of two electric fluids - ib.
7. The >econd hypothesis convenient ib.
8. Explanation of the effects already
9. Electricity developed by various
bodies when submitted to fric-
tion - -. - 5
No certain test for determining
which of the bodies submitted
to friction receives positive, and
which negative electricity - - ib.
to. Classification ot positive and nega-
tive substances 6
loa. Both electricities always produced
together . .... 7
II. Method of producing electricity by
glass and silk with amalgam - ib.
IZ. Conductors and nonconductors - 7
13. Degrees of conduction - ib.
14. Insulators - - - 8
15. Insulating stools .... ib.
16 Electric^ and non-electrics obsolete
terms - - - ib.
17. Two persons reciprocally charged
with co trary electricities placed
on insulating stools ... 9
18. The atmo>phere a nonconductor - ib.
19. Effect of rarefying the air - - ib.
zo. Use of the silk string which sus-
pends pith balls - - - - 10
n. Water a conductor - - ib.
zz. Insulators must be kept dry - - 10
zj. No certain test to distinguish con-
ductors from nonconductors - ib.
Z4. Conducting power variously af-
fected by temperature - ib.
Z5. Effects produced by touching an
electrified body with a conductor
which is not insulated - n
z6. Effect produced when the touching
conductor is inflated ... ib.
zy. Why the earth is called the com-
mon reservoir .... t 'b.
z8. Electricity passes by preference on
the best conductors ... -iz_
Z9- Action of electricity at a distance - 12
30. Induction defined - - - - 13
31. Experimental exhibition of its ef-
33 Effects of sudden inductive action - 15
34. Example in the case of a frog - 16
35 Inductive shock of the human body ib
36. Development of electricity by in-
duction - - - - - ib.
37. Description of an electrical ma-
Parts of electrical machines - - ib.
The rubber - - - - - ib.
39. The conductors - ... 16.
40. The common cylindrical machine - /A.
Explanation of its operation - 18
41. Nairne's cylinder machine - - ib.
4Z. Common plate machine, known as
Van M-irum's - - - - 19
43. Ramsden's plate machine - - zi
44. Armstrong's hydro-electrical ma-
chine . - -.- 22
45. Appendages to electrical machines 24
46. Insulating stools .... ib.
4 7. Discharging rods .... ib.
,8. Jointed dischargers - - - 15
^9. Universal discharger ... t 'b.
CONDENSER AND ELBCTROPHORCS.
50. Reciprocal inductive effects of two
conductors ... - - 26
51. The condenser - 28
52. Dissimulated or latent electricity - tb.
53. Free electricity .... ib.
54. Construction of condensers - - 29
55. Collecting and condensing plates - iL.
56. Cuthbertson's condenser - - ib.
57. The electrophorus - - 30
58. Electroscopes, their general prin-
ciples ...... 31
59. Pith-ball electroscope - - -31
66. The needle electroscope ... ib.
6t. Coulomb's electroscope - - - 33
62. Quadrant electrometer - - - ib
63. Gold-leaf electroscope - - - 34
64. The condensing electroscope - - ib.
THE LEYDEN JAR.
The principle of the Leyden jar
The fulminating pane ...
Discovery of the electric shock
The Leyden jar ....
Effect of the metallic coatings
Experimental proof that the charge
adheres to the glass and not to
the coating .....
Improved form of the Leyden jar -
Lane's discharging electrometer
Cuthbertson's do. do.
Harris's circular electrometer
Charging a series of jars by cascade
Electric battery ....
Common do. ....
Manner of estimating the amount of
the charge .....
. Residual charge - -
LAWS OF ELECTRICAL FORCES.
77. Electric forces investigated by Cou-
78. Proof plane -
79. Law of electrical force similar to
that of gravitation -
80. Distribution of the electric fluid on
81. It is confined to their surfaces - 55
82. Intensity of an electrical charge
upon a conductor less in propor-
tion as the total surface of 'the
conductor is greater - - - 56
83. Faraday's apparatus - - - 57
84. How the distribution of the fluid
varies ..... 59
85. Distribution on an ellipsoid - - ib.
86. Effects of edges and points - - ib.
87. Distribution of electric fluid varied
by induction - - - 61
88. Experimental illustration of the
effects of a point - - - ib.
89. Rotation produced by the reaction of
points ..... 62
90. Experimental illustration of this
principle ... - 6?
he electrical orrery
The electrical blow pipe
910. Explanation of foregoing effects - 65
MECHANICAL EFFECTS OF ELECTRICITY.
03. Attractions and repulsions of elec-
trified bodies .... 66
94. Action of an electrified body on a
nonconductor not electrified - 67
95. Action of an electrified body on a
nonconductor charged with like
electricity - - - - - ib.
96. Its action on a non-conductor
charged with opposite electricity - ib.
on. Its action on a conductor not elec-
98. Its action upon a conductor charged
with like electricity - - 68
99. Its action upon a conductor charged
with opposite electricity - - ib.
ico. Attractions and repulsions of pith
balls explained .... ib.
101. Strong electric charges rupture
imperfect conductors - .69
lot. Curious fact observed by M. Tre-
mery ... - 70
103. Wood and glass broken by discharge ib.
104. Electrical bells - 71
105. Repulsion of electrified threads - 72
ico. Curious effect of repulsion of pith
107. Electrical dance - - - - 73
108. Curious experiments on electrified
109. Experiment with electrified sealing
wax -.. - - 74
no. Electrical see-saw ... ib.
THERMAL EFFECTS OF ELECTRICITY.
Hi. A current of electricity passing
over a conductor raises its tem-
112. Experimental verification. Wire
ib. heated, fused, and burnt
113. Thermal effects are greater as the
t'J. conducting power is less - - ib.
114. Ignition of metals - ib.
55 115. Effect of fulminating silver - - 76
116. Electric pistol - 76
117. Ether and alcohol ignited - - 77
1 18. Resinous powder burned - - 78
119. Gunpowder exploded - - - ib.
120. Electric mortars - - - ib.
121. Kinnersley's thermometer - - ib.
LUMINOUS EFFECTS OP ELECTRICITY.
izi. Electric fluid is not luminous
123. Conditions under which light is
developed by an electric current
124. The electric spark -
124/1. Duration of the spark ...
12$. Electric brush
120. The length of the spark
127. Discontinuous conductors produce
luminous effects ....
128. Various experimental illustra-
129. Effects of rarefied air -
130. Experimental imitation of the
auroral light -
131. Phosphorescent effect of the
spark > .....
132. Lichtenberg's figures -
1 33. Experiments indicating specific
differences between the two
134. Electric lightabove the barometric
135. Cavendish's electric barometer -
136. Luminous effects produced by im-
perfect conductors ...
137. Attempts to explain electric light.
The thermal hypothesis -
138. Hypothesis of decomposition and
139. Cracking noise attending electric
140. Electric shock explained - - 88
141. Secondary shock ... - 89
142. Effect produced on the skin by
proximity to an electrified body - ib.
143. Effect of the sparks taken on the
144. Methods of limiting and regula-
ting the shock by a jar - - ib.
145. Effect of discharges of various
146. Phenomena observed in the ex-
amination after death by the
147. Effects of a long succession of
moderate discharges - - - 90
148. Effects upon a succession of
patients receiving the same dis-
charge - - - - - ib.
149. Remarkable experiments of Nol-
let, Dr. Watson, and others - ib.
CHEMICAL AND MAGNETIC EFFECTS OF
150. Phenomena which supply the
basis of the electro-chemical
theory .... 91
151. Faraday's experimental illustra-
tion of this - - - - - ib.
152. Effect of an electric discharge on
a magnetic needle ... ib.
1 53. Experimental illustration of this - 92
154. Effect of an electric discharge on a
suspended magnet - ib.
SOURCES OF ELECTRICITY.
155. Sources of electricity classified - 93
156. Mechanical sources of electricity - i(>.
157. Development of electricity by heat 94
SIMPLE VOLTAIC COMBINATIONS.
158. Discovery of galvanism - - 96
159. Galvani's theory -
160. Volta's theory
161. Electromotive force - - 99
162. True explanation of results above
described - .... IQO
163. Development of electricity by
chemical action ... jot
164. Formation of an electric current - 102
165. Direction of the current - -103
166. Chemical changes accompanying
the production of the electric
current - - - - - 103
167. Effect of connecting the plates - 104
168. Direction of the current through
the liquid 105
169. The galvanic current is a circula-
tion of electricity ... ib.
170. Power of various galvanic com-
171. Electro-chemical series - - ib.
172. Necessity for using a liquid In order
to produce a galvanic current - io
A galvanic current may be pro-
dncea by the mutual action of
liquids ..... 108
Production of a current by the
combination of two gases - - 109
Conditions needed lor the pro-
duct ion of a constant current - ib.
Smee'sN system - no
Daniell's system - - - - in
Chemical theory of a Daniell's
Grove's system -
Hanson's system -
Volta's invention of the pile - 117
Explanation of the principle of
the pile - - - - - 118
Pole* of the pile - 119
Volta's first pile - - - - ib.
The couronne des tasses - - ib.
Cruii- shank's arrangement - - 120
Wollaston's anangement - - ib.
Vuncn's battery - - - - 121
Helical pile of Faculty of Sciences
at Paris ..... 122
Conductors connecting the ele-
ments - - - 124
Pile may be placed at any dis-
tance from pUce 'f experiment 125
Memorable piles. Davy's pile at
the Royal Institution - ib.
Napoleoh'f pile at Polytechnic
School - - - - - ib.
Children's great plate battery - ib.
Ha:e's deflagrator - - - ib.
Stratingh's deflagr.tor - - 126
Vepy's pile at the London Institu-
tion - - - ib.
These and all similar apparatus
h ve fallen into disuse - - ib.
Dry piles ..... ib.
D-luc'spile ..... &
Zamboni's pile -
Voltaic j<>ux de bague -
Piles of a single metal
Hitter's secondary piles
209. The voltaic current - 129
210. Voltaic circuit - ijo
211. Case 'in which the earth com-
ple f e> the circuit ... ib.
212. Methods "f connecting the poles
with the earth . - - -131
3*13. Various denominations of cur.
rents - . - - ib.
214. The electric fluid forming the
current not necessarily iu mo-
215. Resistance of conductors - - 132
216. Difference between the electrical
machine and the voltaic battery
217. Laws of voltaic currents - -
218. The intensity of the current is the
same in every part of the same
circuit - - - jj j
219 Relation between strength of cur-
rent, electro-motive force, and
resistance : Ohm's law - - ib.
220. In'ernal and external resistance - 134
221. Effect of increasing the number of
cells ...... ib.
222. Effect of increasing the size of
the plates - - - - - 135
223. Method of coating the conducting
wires - -_.- 156
224. Supports of conducting wire* - ib.
225. Ampere's reotrope to reverse the
current - - - - - ib.
226. Pohl's reotrope - - - - 137
227. Electrodes - - - - - 138
228. Floating supports for conducting
wire - - - ib.
229. AmpSre's apparatus for supporting
movable currents ... ib.
230. Velocity of electricity ... 139
RECIPROCAL INFLUENCE OF RECTILINEAR
CURRENTS AND MAGNETS.
231. Mutual action of magnets and cur-
rents . - -._
232. Electro-magnetism -
233. Case of a needle free to oscillate
in a horizontal plane -
234. Rule by which the foregoing effects
may be remembered ...
235. Case of a needle oscillating in a
vertical plane - - - ~
236. Action of a vertical current on a
needle oscillating in a horizontal
237. Direction of the force exerted by
a rectilinear current upon each
pole of a magnet -
238. Action of a rectilinear current upon
a magnet free to oscillate about
some point other than its centre
239. Apparatus to measure intensity of
this force - - - - -
240. Intensity varies inversely as the
distance ... _
241. Attractive force exerted upon a
magnet by aconduetor conveying
a current - - . - -
242. A cur lent tends to make a mag-
netic pole revolve round it - -
243. The forces which act between cur-
rents and magnets are mutual -
244 Apparatus to illustrate the electro-
magnetic rotation - -
245. To cause either pole of a magnet
to revolve round a fixed voltaic
246. To cause a movable current to
revolve round the fixed pole of
a magnet - - . _ -
247. Ampere's method - - - -
248. To make a magnet turn on its own
axis by a current parallel to it -
RECIPROCAL INFLUKNCE OF CIRCULATING
278. Conditions on which a needle is
magnetised positively and nega-
140. Front and back of circulating cur.
279. Results o,"S;ivary's experiments - ib.
280. Magnetism imparted to the needle
250 Axis of a current - il>.
251. Reciprocal action of circulating
substance which surrounds it - 165
281. Formation of powerful electro-
252. Intensity of the force vanishes
when the distance of the pole
bears a very g eat ratio to the
diameter of the current - - 154
253. But the directive power of the
282. Conditions which determine the
force of the magnet - - -167
283. Electro, magnet of Faculty of
Sciences at Paris - - - ib.
284. Forces of electro-magnets in ge-
254 Spiral and helical currents - - 155
255. Expedients to render circulating
currents movable, 155 ; Ampdre
and Delarive's apparatus - - ib.
256. Rotatoiy morion imparted to cir-
cular current by a magnetic pole 156
257. Progressive motion imparted to it ib.
258. Reciprocal action of the current
285. Electromagnetic power applied as
a mechanical agent - - - ib.
286. Electro-motive power applied in
the workshop of M. Froment 168
287. Electro - motive machines con-
structed by him, 170; descrip-
tions of the same - - - 171
287*. The electro motive machine of
259. Action of a magnet on a circular
floating current - ib.
260. Reciprocal action of the current
on the magnet - - - - 157
261. Case of unstable equilibrium of
the current .... ib.
162. Case of a spiral current - - ib.
265. Circular or spiral currents exer-
cise the same action as a magnet 158
264 Case of a helical current -, - ib.
265. Method f neutralising the effect
of the progressive motions of
288. Applied as a sonometer - - 175
289. Momentary current by induction ib.
290. Experimental illus ration - - 176
291. Momentary currents produced by
magnetic indut tion - 177
292. Experimental illustrations - - ib.
293. Inductive effects produced by a
permanent magnet revolving un-
der an electro-magnet - - 179
294. Use of a contact breaker - - 180
295. Magneto-electric machines - - ib.
296. Effects of this machine, its medical
266. Right handed and left handed
297. Clarke's apparatus - - -183
267. Front of current of each kind - ib.
268. Magnetic properties of helical
currents their poles determined id.
269. Experimental illustration of these
299. Ruhmkorff s apparatus to produce
currents of tension - 185
300. Stratification of electric light - 186
joi. Peculiar pronerties of the direct
270. The front of a circulating current
has the properties of a south,
and the back those of a north,
302. Statham's apparatus - - - 188
303. Inductive effects of the successive
convolutions of the same helix - 189
171. Adaptation of any helical current
to Ampere's and Delarive's ap-
currents produced upon revolv-
ing metallic discs Researches
272. Action of a helical current on a
magnetic needle placed in its
axis - 161
and Faraday - - - - ib.
273. Inductive effect of a voltaic cur-
rent upon a magnet, 162; soft
iron rendered magnetic by vol-
taic currents ; sewing needles
attracted bv current - - - 162
274. Magnetic induction of a helical
current - - - - - l6j
275. Pol irity produced by the induction
of helical currents ... /ft.
276. Consecutive points produced - ib.
277. Inductive action of common elec-
tricity produces polarity - - ib.
INFLUENCE OP TERRESTRIAL MAGNETISM
ON VOLTAIC CURRENTS.
305. Direction of the earth's magnetic
attraction - - - 192
306. In this part of the earth it corre-
sponds to that of the boreal or
southern pole of an artificial
magnet - - - - - ib.
307. Manner of ascertaining the di-
rection of the force impressed
by terrestrial magnetism on a
curient - - - - - ib,
308. Ve tical current - - - - 19}
309. Horizontal current in plane of
magnetic meridian ... ib.
310 Horizontal current perpendicular
to magnetic meridian - - ib.
311. Horizontal current oblique to
magnetic meridian - 193
312. Effect of the earth's magnetism
on a vertical current which turns
round a vertical axis ... 194.
313. Effect on a current vhich is capa-
ble of moving in a horizontal
plane ...... ib.
314. Experimental illustrations of these
effects. Pouillet's apparatus - ib.
315. Its application to show the effect
of terrestrial magnetism on a
horizontal current ... 156
316. Its effect on vertical currents
shown by Arape're's apparatus - ib,
317. Its effect on a circular current
shown by Ampere's apparatus - ib.
318. Its effects on a circular or spiral
current shown by Delarive's
floating apparatus ... iyj
319. Astatic currents formed by Am-
pdre's apparatus - - ib.
320. Effect of earth's magnetism on
spiral currents shown by Am-
pere's apparatus - ib.
321. Effect on a horizontal current
shown by Pouillet's apparatus - 198
322. Effect of terrestrial magnetism
on a helical current shown by
Ampere's apparatus - ion
323. The dip of a current illustrated
by Ampere's rectangle - - ib.