IV INDEX TO 
Laplace’s formula for determining the rapidity 
of the motion of sound in vapors and gases, 
81. 
Lavoisier and Laplace’s method of determining 
the specific heat of bodies, 102. 
Lens, the erystalline, 125. 
Lenses, six kinds of, 119; principle of, 120 ; 
formation of images of objects by, 121; 
achromatic, 124. 
Leslie’s differential thermometer, description and 
engraving of, 105. 
Lever, the, 8; different kinds of, ib. ; applica- 
tious of, and mathematical formule respect- 
ing, 9-11. 
Leyden jar, the, 153; experiment showing that 
the charge resides in the giass, 154. 
Light, propagation of, 109 ; law of diminution of, 
110; velocity of, ib. ; reflection of, ib. ; refrae- 
tion of, 116; composed of variously colored 
rays, 122 ; duration of impression of, on the re- 
tina, 127 ; interference and diffraction of, 131 ; 
actual nature of, two hypotheses concerning, 
ib. ; reflection and refraction of, explained by 
the undulatory theory, 133; polarization and 
double refraction of, 136; chemical action of, 
139; possesses magnetizing power, 146 ; elec- 
trical, 154; the zodiacal, 236. 
Lightning, identical with electricity, 242 ; three 
kinds of, 243 ; heat, 244; course of its pas- 
sage to the earth, ib.; effects of, 245; the re- 
turning stroke, ib.; rods, 246; three classes 
of lightning rods, 247. 
Lightning plate and tubes, 155. 
Liquids, pressure of, 37; Haldat’s apparatus, 35 ; 
attraction between solids and, 43; dynamics 
of, 46 ; conversion of, into vapors or gases, 95. 
Machines, simple, 8; various electric, 150; the 
hydro-electric of Eisenlohr, 151; magneto- 
electric rotating, 179. 
Magic lantern, the, 130. 
Magnet, the natural and artificial, 140 ; method 
of determining the intensity of, 144; Duhamel 
and CEpinus’s methods of preparing an artifi- 
cial, 145; the magnetic force destroyed by 
heat, 146; magnetic battery, ib. ; rotation of 
a, round its own axis, 176; magnetic declina- 
tion, inclination, and intensity, how represented 
on charts, 252. 
. Magnetism, 140 ; development in iron or steel, 
141; magnetic action of the earth, ib. and 
249 ; laws of, investigated by Gauss and 
Weber, 143; connexion between electricity 
and, 163, action of terrestrial or galvanic 
currents, 173 ; electrical currents produced by, 
178; rotation, 181; connexion between the 
aurora and, not doubtful, 255. 
Magneto-electrie rotating machines, 179. 
Magnetometer, the, 249. 
Mariotte’s law respecting gaseous volume, 52. 
Materials, strength and stress of, 17.. 
Matter. See Bodies. 
Mechanical powers, 8. 
Mechanics, 5. 
Melloni’s thermo-multiplier, 105; experiments 
on the passage of heat rays, 106, 107. 
Mercury, eligibility of, for filling thermometer 
tubes, 89. 
Meteorie stones, 240. 
Meteorology, 184. 
Microscope, simple and compound, 128, 129 ; 
the solar, 129. 
658 
PHYSICS. 
Mirage, explanation of the, 229 ; various classes 
of, 230. 
Mirror, method of finding the position of the 
image in a plane, 111; nature of the image 
tort in a concave, 115; spherical convex, 
ib. *. 
Mistral, the, of southern France, 205. 
Momentum, definition of, 9, 36. 
Monochord, the, invented by Savart, 79. 
Monsoons, causes of the, 200. 
Montgolfier’s hydraulic ram, 48 ; his air-balloon, 
62 
Morse’s telegraph, 171. 
Motion, theory of, 25 ; modifications of the New- 
tonian laws of, 26 ; equable and varying, ib. 
Miiller, attempt of, to produce the sounds of the 
human voice, artificially, 83. 
Nairne’s cylinder electrical machine, 150. 
Natural philosophy, branches of science included 
hasan 
Needle, the magnetic, 142; dipping, ib.; action 
of the earth on, 143; oscillations of the decli- 
nation, ib.; asteel, may be magnetized by 
light, 146 ; the electric, 147; oscillations of 
the magnetic, 253. 
Neef and Wagner’s apparatus for exhibiting in- 
duction currents, 177. 
Neutral axis, the, 18. 
Newton’s hypothesis respecting the blue color of 
the sky, untenable, 226. 
Newtonian Jaws of motion, modifications of 
the, 26; telescope, 131. 
Nicholson’s areometer, 42. 
Nobili pile, description of the, 183. 
Norremberg’s polariscope, 136. 
Observatories, magnetic, 250. 
(Epinus’s method of preparing artificial mag- 
nets, 145. 
Oersted’s piezometer, 82 ; suggestion of the con- 
nexion between magnetism and electricity, 
163. 
Optical instruments, division of, into catoptric, 
dioptric, and cata-dioptric, 128. 
Optics, 109. 
Organs, construction of, 76; tongue-work and 
reed-pipes, 80. 
Oscillations of the pendulum, laws of the, 32; 
of stretched strings, method of determining, 
79; of the declination needle, 143. 
Pan’s pipe, the, 76. 
Papin’s digester, 96 ; construction of the earliest 
steam apparatus on record, 99. 
Pappus, an ancient Greek mathematician, 8. 
Parachute, the, 63. 
Parallelogram of forces, the, 5; of velocities, 
26. 
Parallelopipedon of forces, 6. 
Parhelia, various cases of, 235 ; explanation of, 
ib. 
Pendulum, the, 32 ; laws of the oscillations of, 
ib. ; Harrison’s gridiron and Graham’s mer- 
curial, 34; discoveries of Galileo, Huyghens, 
Newton, and Richer in relation to the, 34, 35 ; 
the length of the seconds’ pendulum dependent 
on its distance from the earth’s centre, 35; 
the ballistic, 37; the electrical, 147. 
Penetration, 2. 
Phenakistoscope, the, 127. 
Photograph, the, 140. 
' Physics, sub-divisions of, 1. 
