INDEX.

like a Prism, ii. 314. Axis of, what, iii. 2 n. Ver-tex, what, ibid. Several kinds of, iii. 2 n. What,and how many Sorts of, iii. ig. Refraction by, iii.24. Double and equally Convex, Rule for findingits Focus universally, iii. 25. Convex, Remedy theFlatness of the Cornea, and Crystalline Humour", iii.40. Convex, Advantages of, iii. 41. The Imper-fection of its Figure, iii. 62 n. How remedied bythe old Opticians, ibid. And how by Sir Isaac New-*ton , iii. 63 n.

Level for a small Distance, ii. 5 n.

sever, what, !. 161. Five Kinds of, i. 164. A Com-pound Pendulum, i. 173 n. Several Properties of,ibid. &seq. Table of Powers, i. 179 n.

Llbration of the Moon, what, iii. I20n.

Lihurkun, Dr. Invention of solar Microscope, iii. 86 n.

Lifting Pump, Construction of, ii. 56 n. An excellentone invented by M. Gojsetand de la Denille , ii. 65 n.

Light, Reflection and Inflection of, i. 38 n. What,ii. 267. The immediate Means of Sight, ii. 268.Remarkable Properties of, ibid. £jf seq. New-tonian Theory of, ii. 270 n. Velocity of its,Rays, ii. 271 n. Weight of insensible, ii. 272 n.The Particles of, have Magnitude, ii. ibid.Reflections from Bodies, ibid. Gf seq. Rays ofreflected from various Mediums, ii. 396. Rays of,Jiow Bodies act upon them, ii. 300 n. Reflection,and Refraction of, how caused, ii. 301 n, Velocityof, ii. 3030. Refrangibility of, ii. 313 n. Rays ofhow reflected, ii. 326. Rays of pervade a rare Me-dium less than a denser, ii. 328. The Reflection ofthe Particles of, ii. 332 n. How variously disposed tobe reflected and transmitted, ii. 337. Velocity of un-known to the Ancients, ii. 273 n - Rays of, howmany Sorts, ii. 7 -

Lightning and Thunder , how caused, i. 37 n.

Line, what, i, 6. Of the Apsides, iii. 87.

Load-Stone. See Magnet.

Lock, what Angle the Gates of one should formwith the Sides of a River, i. 228.

Longitudt of a Place, hqvy determined by Jupiter’s Sa-tellites,