INDEX.

tine of every Degree, Table of correspondent Partsfor, i, 226 n. Of the Angle of Incidence andfraction, Method for finding, ii. 304 n. fs" seq. OfIncidence and Refraction in yellow Light, a Tableof, ii. 308 h.

Slare, Dr. his remarkable Experiment to produce Air,ii. 115 n.

Smith , Dr, his catoptric Microscope, iii. 51 h.

Solar System proved to be true, iii. 129. Telescopeand Microscope, see Telescope and Microscope.

Soldering accounted for, i. 33 n.

Solid, what, i. 6.

Solidity, what, 1. 7.

Solstices of Solstitial Points, what, iii. 17H.

Sounds, what, ii. 215. How propagated, ibid; Prin-cipal Phænomena of explained, ii. 225 n. U seq.Distinction of, whence, ii. 231. Utmost Limits of,what, ii. 232. Velocity of, ii. 233. How far au-dible, ii, 233 n. Real Velocity of investigated, ii.236 n. Table of different Estimates of, ii. 237 n.Motion of equable, found by Various Experiments,

ii. 237 n. Table strewing it, ii. 308 n. Accele-ration of, depends on the Wind, ii. 240 n. Single;fee Echo.

Sonorous Body, hew it agitates the Air, ii; 232 n.

Specific Gravities, Table of; i. 290 n. & seq.

Spectacles, concave, Use of, iii. 40. Convex, Advan-tages of, iii. 41. Common, Eault of, iii; 398. Dif-ference between them and visual Glasses, iii. 406;

Speculum, Convex and concave, iii. 75 n. Curious Pro-perty of, iii. 9 n.

Sphere , Property of in Glasses, iii. 17 n. Of Attractionproved by Experiments, i. 22. Of Archimedes , de-scribed by Clctudian, iii. 165 n. £5 seq. Right, what,

iii. 261. Parallel, what, iii. 236. Oblique, what,iii. 265. Projection of in Piano, what, iii. 293.Orthographic Projection of delineated, iii. 306 n. Itsseq. Stereographic Projection of, on what Principledepending, iii. 308 n.

Spitits, Proof, best Method of trying, i. 283 n.

Spots in the Sun first discovered by Galileo, iii. ill n.Some of considerable Magnitude, iii. 112 n. Pro-portion of their Surface to that of the Earth, ibid;

Irregular