INDEX TO PITIYSICS. + 
Piezometer, the, 82. 
Pipes, reed, 80. 
Plummet, the, deviations of, in the vicinity of 
mountains, 35. 
Pluviometer, the, 217. 
Pneumatics, 5, 65. 
Polariscope, the, 136. 
Polarization of light, 136. 
Poles, magnetic, 142. 
Polyzonal lens, 121. 
Porosity, 2. 
Pressure, lateral, 47. 
Prism, description of the, 117; decomposes 
natural colors of bodies, as well as white solar 
light, 123. 
Projectiles, theory of, 30. 
Psychrometer, the, preferable to other hygrometric 
apparatus, 208. 
Pulley, the, 8; fixed and movable, 13; White’s, 
f°: 
Pump, the common and forcing, 60. 
Pyrometers, 84; Muschenbroek’s, Wedgewood’s, 
and Daniell’s, 87. 
Pyronomies, 84. 
Radiation of heat, 104. 
Rain, production of, 217 ; annual fall of, in dif- 
ferent portions of the earth, 218 ; distribution 
of, throughout the year, 220; purity of rain 
water, ib. 
Rainbow, explanation of the, 231; secondary 
bows, 232 ; lunar, 233. 
Rain gauge, 217. 
Rays, reflected from plane surfaces, 111; from 
polished curved surfaces, 114; refracted, 116; 
course of, in a prism, 118 ; passage of, through 
differently shaped lenses, 120; colored, 122; 
dispersion of, 123 ; passage of, to the retina, 
125 ; effect of coincidence of, at a very acute 
angle, 132; interference of, ib.; polarization 
and double refraction of, 137. 
Reaction of water, 47. 
Reaumur’s scale, graduation of, 85. 
Redfield’s law of storms, 202. 
Reflection, angle of, 111; of light, explained by 
the undulatory theory, 133; phenomena of 
atmospheric, 228. 
Refraction, angle of, 116, 118 ; various pheno- 
mena of atmospheric, 228; varies at different 
times, 229. 
Refraction of light, laws of, 116 ; through lenses, 
119 ; explained by the undulatory theory, 133 ; 
double, 136. 
Regulators, water, 67. 
Resultants, 5. 
Retina, the, 124; its retention of impressions 
after an object has been withdrawn, 127. 
Ritehie’s electro-magnetic apparatus, improved, 
167. 
Rochon’s micrometer, 138. 
Rotation magnetism, 181. 
Rouse’s estimate of the velocity of the wind, 198. 
Rumford’s, Count, differentia! thermometer, 104. 
Rutherford’s self-registering thermometer, 188. 
Saussure’s hair hygrometer, 206 ; diaphanometer, 
225 ; cyanometer, 226. 
Savart’s sound tubes, 75 ; monochord, descrip- 
tion of, 79; experiments on the velocity of 
sound, 82. 
Savery, the first to make a practical application 
of the steam-engine, 99. 
Schweigger’s galvanometer or multiplier, 163. 
Scoresby, his observations on snow erystals, 221 
Screw, the, 8, 15; endless, 16; Hunter’s differ: 
ential, ib. 
Seebeck, the discoverer of thermo-electricity, 
182. 
Seasons, occurrence of the, in the several zones 
186. 
Sextant, the reflecting, 113. | 
Shadows, full and half, 110. 
Shooting stars, 238 ; recorded showers of, 239. 
Sight, sensation of, 124. 
Siren, the, an instrument for determining the 
vibrations of tones, 78. 
Sirocco, the, 204. 
Snow, form of the crystals of, and region of, 
221; storms, 222; density of, ib. 
Snow lines, table of, 192. 
Solano, the, of southern Spain, 204. 
Solar spectrum, the, 118, 122 ; microscope, 129. 
Soleil’s apparatus for exhibiting the colored rings 
of polarization, 139. 
Solids, 3 ; statics of, 5; strength of, considered, 
17; dynamies of, 25 ; specific gravity of, 39 ; 
attraction between liquids and, 43 ; methods 
of ascertaining their expansion at high degrees 
of temperature, 86; practical applications of 
their expansion and contraction, 87; may 
transmit heat rays, 106 ; possess different con- 
ducting powers of heat, 108. 
Sound, theory of, 69; manner and velocity of 
its transmission through the air, 72 ; reflection 
of, 73; formation of musical tones, 74 ; its 
diffusion through all ponderable matter, 81 ; 
formula for determining its motion in vapors 
and gases, ib. ; experiments on the velocity of, 
82. 
Specifie gravity, 4, 39. 
Spectra of the first and second orders, 134. 
Spectrum, the solar, 118, 122. 
St. Elmo’s fire, 249. 
Stars, causes of the twinkling of the, 228; 
shooting, 238. 
Statics of solid bodies, 5; divisible into three 
sections, ib.; theory of the strength of bodies, 
17; of fluids, 37; of aeriform bodies, 49. 
Steam-engine, the, 99. 
Steel, use of, for artificial magnets, 141, 145. 
Steel yard, the, 9. 
Steinheil’s electric telegraph, 170. 
Stohrer’s electro-magnetic machine, 166, 181 ; 
his improvement on Daniel’s battery, 167. 
Storms, cause of, and where most prevalent, 
202 ; magnetic, 253. 
Strength and stress of materials, 17. 
Syphon, the, 58. 
Talbotype, the, 140. 
Tantalus, cup of, 58. 
Tartini, the tones of combination or accessory 
sounds of, 81. 
Telegraph, the electro-magnetic, Wheatstone’s, 
168 ; Steinheil’s, 170 ; Morse’s, 171 ; effect of 
lightning on the, 245. 
Telescope, the refracting and reflecting, 130 ; 
different kinds of, ib. 
Temperature, unequal, of the earth’s surface, 
185, 190; method of ascertaining the mean 
temperature of a place, 188 ; ratio of decreasa 
of, according to elevation, 191; of springs, 
193 ; daily variations of, less at sea than on 
land, ib. 
659 
