INDEX TO PHYSICS. 
iil 
Fechner and Becquerel’s improvements of the dry | Heat, science of, 84; expansion of bodies by, ib. ; 
pile, 161. 
Fire balls identical with shooting stars, 239. 
Flexion, axis of, 18. 
Fluids, statics of, 37; law of Archimedes with | 
respect to bodies immersed in, 39. 
Flying machine of Henson, 64. 
Focus and focal length, 120. 
Fog, production of, 212; principal localities of, 
213 ; dry, 214. 
Fohn, the, a continuation of the sirocco, 204. 
Forces, general ideas respecting, 9. 
Fortin’s barometer, 51. 
Fourneyron’s turbines, 48. 
Franklin, proves the identity between electricity 
and lightning, 242 ; invents the lightning rod, 
246. 
Franklin plate, the, 152. 
Fresnel lens, 121. 
Fresnel’s experiment on the coincidence of rays 
of light at a very acute angle, 132. 
Frost, 212. 
Galilean telescope, the, 130. 
Galvanic batteries, 157; three modifications of, 
160. 
Galvanism, nature of, 156; the galvanic circuit, 
157 ; action of the galvanic current, 161, 165; 
laws of the magnetic action of the galvanic 
current, 172; mutual influence of galvanic 
currents, 174 ; induction currents, 177. 
Galvanometer, the, 163; the differential, 182, 
Galvanoplastics, art of, 162. 
Gambey’s goniometer, 113; intensity compass, 
143. 
effects of, in changing the state of aggregation 
of bodies, 90; apparatus for measuring la- 
tent, 98; methods of determining the specific, of 
bodies, 102 ; transmission of, 104; absorption, 
reflection, and transmission of rays of, 105 ; 
heat rays capable of refraction, 107; con- 
duction of, 108; sources of, 108; animal, 
109 ; produced by mechanical means, ib. ; de- 
stroys the magnetic force, 146; electric cur- 
rents produced by, 182; distribution of, on the 
earth, 185 ; lightning, 244. 
Henley’s quadrant electrometer, 151 ; universal! 
discharger, 153. 
Henry, Prof. Joseph, his application of electro- 
magnetism to the production of magnets, 165 ; 
| his discovery of the applicability of the electro- 
| magnet to telegraphs, 168; discoveries re- 
specting induction currents, 177 ; observations 
on the effect produced by lightning on the 
magnetic telegraph, 245; plan for protecting 
houses from lightning, 247. 
Henson’s flying machine, 64. 
Hero’s ball, 59 ; fountain, 60. 
Howard’s classification of clouds, 214. 
Humboldt’s isothermal lines, 189 ; table of snow 
lines, 191 ; theory of the zodiacal light, 237. 
Hunter's differential screw, 16. 
Hurricanes, 202. 
Hydraulic ram, 48 ; press of Bramah, 61. 
Hydrodynamics, or hydraulics, 5, 46. 
Hygrometers, use of, and description of various, 
206. 
| Hydrostatic balance, the, 40. 
| Hydrostatics, 5, 37. 
Gases, statics of, 49; methods of investigating | 
the density of, 90; specific heat of, investi- 
gated by De la Roche and Berard, 103 ; re- 
fractive powers of, proportionate to their den- 
sities, 119 ; the constituent, of the atmosphere, 
184. 
Gasometer, the, 66. 
Gauss’s magnetic researches, 143. 
Gay Lussac’s areometer, 42 ; apparatus to deter- 
mine the amount of capillary attraction, 43 ; 
hand air-pump, 55; method of ascertaining 
the density of watery vapor, 93; lightning 
rod, 248. 
Geodynamics and geostatics, 5. 
Goniometer, reflecting, 112. 
Graham’s mercurial pendulum, 34. 
Gravitation, 4, 7. 
Gravity, centre of, 7. 
Greenwich, magnetic observatory at, detailed 
description of, 250. 
Grimaldi of Bologna, the discoverer of diffrac- 
tion of light, 134. 
Grove’s battery, 159. 
Guericke, Otto, the inventor of the air-pump, 55. 
Hail, two kinds of, 222; hailstones, form and 
size of, 223 ; when hail storms most frequent, 
224 ; injuries caused by, ib. ; hai] conductors, 
inutility of, 225. 
Haldat’s apparatus to. illustrate the pressure of 
liquids, 38. 
Halo, two kinds of, 233 ; descriptions of several, 
by Bouguer, Scoresby, and others, 234. 
Hampton balloon, the, 63. 
Hare’s calorimeter, 158. . 
Harrison’s gridiron pendulum, 34. . 
Hearing, organs of, 83. ° 
ICONOGRAPHIC ENCYCLOPADIA,—VOL. I, 
| Iceland spar, double-refracting property of, 138. 
Ignis fatuus, the, 237; various theories of its 
cause, 238. 
Images of objects, formation of, by lenses, 121 ; 
in mosaic composite and simple eyes, 124; 
why one image only is seen, though two are 
formed, 126. 
Impact, theory of, 36; of water, 47. 
Impenetrability, 2. 
Incidence, angle of, 111, 116. 
Inclined plane, the, 8, 14. 
Induction, explanation of electrical, 149; eur- 
rents, 178. 
Inertia, 3. 
Interference of light, the, 132. 
Intermitting spring, the, 59. 
Iridescence, explanation of, 136. 
Iron, development of magnetism in, 141 ; rods 
and bars may become magnetic by position, 
144, 
Irradiation, definition of, 126. 
Isoclinic, isodynamic, and isogenic lines, 252. 
Isothermal lines of Humboldt, 189. 
Jacobi and Lenz, laws of the magnetic action 
of the galvanic current determined by, 172. 
Kaleidoscope, description of, 112. 
Keplerian telescope, the, 130. 
Kinnersley’s thermometer, 149. 
Kopp’s differential barometer, 53 ;. his volumeter, 
54. 
Lagrange’s propositions concerning the vibrations 
of strings, 79. 
Land whirls, 206. 
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