Hi INDEX TO PHYSICS. 
Cagniard dela Tour’s apparatus for determining 
the number of vibrations in a tone, 77. 
Calorimeter, the, 158. 
Camera lucida and obscura, description of the, 128. 
Cartesian devils, the, 40. 
Cassegrainian telescope, the, 131. 
Castor and Pollux, explanation of the phenome- 
non so called by the ancients, 249. 
Catoptries, 110. 
Centigrade scale, or scale of Celsius, graduation 
of, 85. 
Centre of gravity, 7. 
Centrifugal force, 31. 
Chamsin, a hot wind of Egypt, description of 
the, 204. 
Chemical action of light, 139. 
Chevalier’s microscope, 129. 
Chladnis sound figures, 71; experiments on 
the velocity of sound, 82; hypothesis of the 
nature and origin of meteoric stones, &c., 
241. 
Clarke’s magneto-electric machine, 180. 
Climatology, 184; climate of a country de- 
pendent on a variety of circumstances, 189. 
Clouds, nature and classification of, 214; posi- 
tion and height of, 215 ; different appearances 
of, 216 ; coloring of, 217. 
Cohesion, 3. 
Colors, seven principal, 122; subjective, 127; 
of thin plates of glass and other substances, 
135, 138. 
Commutator, the, 166. 
Compass, the, 142; daily variation of the, 143 ; 
Gambay’s intensity, ib.; the tangent and sine, 
164. 
Compensation bars or strips, 88. 
Compressibility, 2. 
Condenser, the, an apparatus for accumulating 
feeble electricity, 154. 
Condensing pump, the, 56. 
Conductors, good and bad, of electricity, 147. 
Coulomb’s methods of determining magnetic 
intensity, 144; determines the law of the 
decrease of magnetic strength, 145; magnetic 
battery, 146 ; electroscope, 147. 
Curved surfaces, reflection from, 114. 
Cyanometer, the, 226. 
Daguerre and Niepce, their method of fixing the 
images of the camera lucida, 139. 
Daniel’s constant battery, 159; improved by 
Stohrer, 167 ; hygrometer, 207. 
Daniell’s pyrometer, 87. 
Days, inequality of the length of, 186. 
De Ja Rive’s apparatus for showing the influence 
of a magnet on galvanic currents, 173. 
De la Roche and Berard’s investigations on the 
specific heat of gases, 103. 
Density, 4. 
Dew, theory of, 209. 
Dew point, the, 207. 
Diaphanometer, the, 225. 
Diathermanous bodies, 106. 
Diffraction of light, the, 135. 
Dioptrics, 116. 
Discharging rod, the, 152; Henley's universal 
discharger, 153. 
Distillation, process of, 97. 
Divisibility, 2. 
Double refraction, 137. 
Drawing of water, the, an effect of atmospheric 
reflection, 228. 
656 
Drosometer, the, 209. 
Dry pile, the, 160. 
Dufay’s theory of two distinct electrical fluids, as 
modified by Symmer, 148. 
Duhamel’s method of preparing artificial mag- 
nets, 145. on 
Dulong, experiments of, and Arago, for verifying 
Mariotte’s law, 52; apparatus for determining 
the elasticity of vapor at very high pressures, 
92; experiments of, on the refractive power 
of gases, 119. 
Dulong and Petit’s method of determining the 
specific heat of bodies, 102 ; experiments on 
the laws of cooling, 107. 
Dutrochet’s experiments on the porosity of 
liquids, 45. 
Dynamics, 5; of solid bodies, 25 ; fundamental 
propositions in, 26 ; of liquids, 46. 
Earth, magnetic action of the, 141; magnetic 
equator and poles, 142; its action on the 
needle simply directive, 143. 
Echo, nature of, 74. 
Efflux, velocity of, 46, 67. 
Eisenlohr’s hydro-electric machine, 151. 
Electric, the, dance, pistol, and mortar, 148, 149 ; 
machine, 150. 
Electricity, 146 ; conductors of, 147 ; confined to 
the surface of bodies, 148 ; positive and nega- 
tive, ib.; method of determining the kind of, 
in a body, 149 ; combined or disguised, J52 ; 
electrical light, 154; may be developed in 
several ways, 156; developed by chemical 
combination or decomposition, 163 ; intimate 
connexion between magnetism and, ib. ; pro- 
duction of electrical currents by magnetism, 
178 ; thermo-electric currents, 182; identical 
with lightning, 242. 
Electro-magnetic telegraph, the, 168 ; effect of 
lightning on the, 245. 
Electro-magnetism, and electro-magnetic ma- 
chines, 165; its employment for telegraphic 
purposes, 168. 
Electrometer, the gold leaf and straw, 147 ; 
Henley’s quadrant, 151; application of the 
dry pile to, 161. 
Electrophorus, description of the, 151. 
Electroscope or electrometer, the, 147. 
Electrotype, theory of the, 162. 
Endosmosis and the endosmometer, 45. 
Equator, the magnetic, 142. 
Equilibrium of forces, 6, 17. 
Ettingshausen’s magneto-electric rotating ma- 
chine, 179. 
Europe, causes of the mildness of the climate 
of, 190. 
Evaporation, 97. 
Exosmosis, 40. 
Expansion, 3. 
Extension and extensibility, 2. 
Eye, the mosaic composite and simple, 124 ; de- 
scription of the simple, 125. 
Falling bodies and projectiles, theory of, 28. 
Faraday’s condensation tube, engraving of, 95; 
experiments on the duration of impressions of 
light on the retina, 127; observations on 
peculiar phenomena relating to the diffraction 
of light, 135 ; discovers the diamagnetic pro- 
perty in bodies, 141; his galvanic apparatus 
begetting its own current, 175. 
Fata Morgana, the, 230 ; instance of, 231. 
