INDEX.

what, ibid. Its Weight manifest from Reason am!Experiments, ii. 121 n. Whence, according to SirIsaac Newton, ii. 119 n. An Element of Bodies, ii,120 n. Table of, ibid. Gravity of indicated by theMercury in the Barometer, ii. 125 n. Spring of towhat owing, ii. 122. Common Experiments forshewing, ii. 129. Its Force of Repulsion exhibsted,11. 135 n. Its Density why different at different Al-titudes, ii. 136. How decreasing upwards, ii.

If of equal Density the Height of the Atmospheremight be determined, ii. 139. But decreasing withthe Pressure becomes indefinite, ii. 141. Altitudeof how determined, ii. 142. Its Density limited, ii.143 n. Its Rarity limited, ibid. Two different Den-sities of found by Experiment, ii. 144 n> Its Rare-faction investigated by Sir Isaac Neivton, ibid. Boun-dary of where fixed, ii. 15711. Method for discover-ing the Altitude of, ibid. Mean Gravity of, what,ii. 150 n. How affecting the animal Functions, ib.Weight of proved by many Experiments, ii. icj.The Pressure of in raising Water how evinced,^ii,.J56. Spring of demonstrable by various Experriments, ii. 157. Uses and Consequences of, ii.173. Necessity of in several Particulars, ii. 174.Heat and Cold in are indicated by the Thermo-meter, ii. 180. Spring of affected by Heat andCold, ii. 181 n. Rarefaction of in the Recipient ofAir-pump calculated, ii. 195 n. Table of, ii.196. Direction of from E. and N. the Effect ofii. 209. Verified in the general Tradk-winds, ibid.Waves of, what, ii. 228.

Air-Gun described, ii. 189 n,

Air-Pump, common, described, ii, 190. Portable de-scribed, ii. 193.

Altitudes of Mercury, or Water, Table of, ii . r ,_ nOf the Air how determined, ii. 142. Of the Sunor Stars, what, iii. 249.

Amplitude, horizontal, of Projection, i, r2o , Differ-ent, of a Projectile, i, 130. Qrtive mid' Occasivewhat, iii. 286 n.

Ampbifcii, who, iii. 282.

Analysts in Natural Philosophy what, i. 4 n.

II d 4 Anemoscope,