INDEX.

60. Galilean, what, iii. 63. Cata-dioptric or Re-flecting, Excellence and Mechanism of, iii. 64. Ae-rial, why so called, iii. 65 n. Brightness of anObject in, what, iii. 68 n. Huygens’s Table cal-culated, of, iii. 71 n. Gregorian, by Sir Isaac New-ton, iii. 76 n. Cata-dioptric, Power of magnifying,iii. 77. Solar, what, iii. 84 n. How used, ibid.A new reflecting one described, 369 sis’ seq.

Thames , Quantity of Water passing daily through esti-mated, ii. 13 n.

Thermometer , what, and how constructed, ii. 180. ItsUses, ii. 181 n. With Spirits of Wine, ii. 181 n.With Linfeed-Oil, ii. 182. Of Farenheit described,ibid. Qurious, Construction of by the Earl of Ca-vendijh , ii. 187 n.

Theory of the Sails of a Wind-mill, i. 220 n. OfWheel-carriages, i. 229, 235 n. Of Pump-workdemonstrated, ii. 45 n. Of the Tides illustrated, ii.91. Of the Compound Barometer, ii. 128 n. OfWind-mills, ii. 212 n. Of Bellows, 217 n. Har-monical, rendered more general, ii. 216 n. Of Light,

ii. 270 n. Of Heat and Cold illustrated, ii. 282 n.Of Compounding and decompounding Colours, ii.363 m Of Vision, iii. 27 n. Lunar, explained,

iii, 319 iff seq. Of the Sun, Earth, Jupiter andSaturn, iii. 356. Of a new Micrometer, iii. 372.

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

Tides , Theory of, ii. 91. OfFIood and Ebb accountedfor, ii. 95. Autumnal, accounted for, ii. 96. Ver-nal, accounted for, ibid. To what ascrioed by theAncients, ii. 98 n. Phænomena of, agreeable toExperience, ii. 109 n.

Time , what, iii. 222. Measured by the Motion of theheavenly Bodies, ibid. Subdivisions of, iii. 223.British, Account of, iii. 240. I he Emendation weuse not fufsicient, and why, ibid. Equation of, howmade, iii. 235. Not measured equally by any na-tural Body, iii. 236.,

Tornados , why so called, ii. 202 n.

Torricelian Vacuum exhibited, i. 64 si?" seq. Tube andExperiment, what, ii. 125 n.

Torrid Zone, see Zone.

Vol. III;. G g Trade-