INDEX.

Mountains of St. Helena, ii. 12. Experiment madoin that Island, ibid. & seq. In the Mediterranean andThames, ibid. An Objection to his Theory of Va-pours answered, ii. 18 n. Form of a Diving-Belldescribed, ii. 175 n. The principal Phænomena ofWind taken from his History and Map, ii. 201 n.Solution of a Problem of Fenus appearing in theDay Time, iii. 135 n. Method of calculating theQuantity of the Tropical Year, iii. 225.

Harmony, what, ii. 255.

Halo's, how formed, ii. 368.

Harmonical Proportion, what, ii. 256.

Harpsichord, ocular, attempted for entertaining the Eye,with Harmonic Colours, ii. 322.

Harvest Moon, Phænomena of explained, iii. 275.

Hawksoee s accurate Method for finding the refractivePower of the Air, ii. 39 n.

Heat and Ebullition accounted for, i. 27 n. And Coldinduated by the Spring of the Air, ii. 181 n. A ge-neral Cause of Wind, ii. 203. What, ii. 279 n.281 n. Of a Polar Day calculated, iii. 187 n, Ofa Summer Tropical Day calculated, iii. 186 n. Of aWinter Tropical Day, iii. 18711, When a Maxi-mum in any given Day, Problem for finding, iii-188 n.

Heliomeier, what, iii. 373. Invented by Servington Sa-vory, ibid. U seq.

Heliojlata. Sec Gravesande.

Hemisphere, Property of, in Glasses, iii. 17 n. Cele-stial, what, iii. 297.

Heteroscii, who, iii. 283.

Hero's Crown. See Archimedes.

History of the principal Phænomena of Winds, ii. 201-

Hyperbola, Properties of, i. 326 n.

Hooke , Dr. Inventor of the Wheel Barometer, ii. 138 n--.

Horary Circle and Index, what, iii. 177.

Horizontal Amplitude of Projection, i. 129. Randomoi Projection, what, i. 129. Instrument to draw aLine truly so, ii. 3 n. Dial, what, iii. 271.

HJkins, Mr. Jojhua, his curious Mercurial Pump, £9improved by Dr. Desaguliers, ii. 57 n.

Hour-Lines, what, iii. 270 n.

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