INDEX. 
Fluid mass in equilibria , physical properties of, 111, 122, 125, 126, 
— Ivory, on its equilibrium, 85. 
Fluids , conducting , Herschel on motions produced in, by electri- 
city, 162. 
Fly , structure of its feet, 385 — of certain parts of, elucidated by 
comparison with the walrus ; see walrus — foot. 
Foot, hind, of walrus, its structure analogous to that of the fly, 234 — 
principle that of a cupping glass, 239. 
Formula for finding the centre of magnetism in ships, 321. 
— — general, of interpolation, applied to chronometrical deter- 
mination of longitudes, 363. 
for finding the ellipticity and compression of a spheroid 
from the two sides and two adjacent angles of a spheroidical tri- 
angle given, 368. 
— — of Bessel for the density of the earth’s atmosphere at any 
height, 58. 
of Atwood for the change of rate of a chronometer arising 
from a change in the arc of vibration, 410. 
■ — of Sir I. Newton for the velocity of sound, 424. 
■ -- - ~ of Laplace, for the same in air of any temperature, pres- 
sure, and moisture, 427. 
— — - — - for the force of gravity in any latitude, 426. 
■ - - for reducing right ascensions and declinations of stars to the 
beginning of the year (as used by Mr. Fallows), 463, 464. 
for the density of air at any temperature, pressure, and de- 
gree of moisture, 427. 
— — — for the attraction of an ellipsoid on any point, 137, 138, 139. 
- — — — - for the attraction of an oblate spheroid of revolution, 139. 
Frost, its approach indicated by the arrival of water birds, 34. 
Fusible metal, its electro-mechanical properties, 186. 
G 
Ganglions , in insects, 7. 
Gas , olefiant, oxygen, hydrogen, &c. ; vide their respective heads. 
Gaseous mixtures, action of platina finely divided, on, 266 et seq. 
at common temperatures, 269 — at increased temperatures, 277 
—analysis of, by ditto, 286- — of hydrogen and oxygen, 269,— 
of olefiant gas and oxygen, 269— of hydrogen and carburetted 
hydrogen with oxygen, 270 — of carbonic oxide and carburetted 
hydrogen with oxygen, 274 — of oxygen, hydrogen, carburetted 
hydrogen and carbonic oxide, 274— of hydrogen, carbonic oxide 
