INDEX.

Descenswn oblique, what, iii. 256.

Dial, Horizontal, what, iii. 271 n. Direct 8. and N,vertical, Reason of, iii. 272 n.

Dialling, Theory of, iii. 69 n.

Diatonic Scale of Mufick, what, ii. 254.

Dionysian Period, what, iii. 247. Why caHed greatthe Paschal Cycle, ibid.

Dioptrick Problems universal Method by Fluxions de-monstrated in many Cafes, iii. 10 n;

Dioptrics , what, iii. 2 n.

Dipping Needle, what, i, 42;

Distillation, Dr. Hale s Method of producing Air by,

ii. 116 n.

Dijfolutim of Metals accounted for, i. 38 mDiversity of Ratio’s, i. 7 n.

Dittcn, curious Property of Speculums discovered by,

iii. 9 n.

Diving-Bell, Use of,, on what depending, ii. 174-Why in the Form of a Bell, ii. 175. Dr. Halley’sForm of described- in 175 ry Inconvenience of, h-178 n. Improvements in, ii. 178 n. Descriptionof Mr. Driewalcl's of, ii. 179■ n.

Divisibility of Matter, what, i. 9. An easy Demonstra-tion of, h 10 n. Another, ibid.

Dominical Letters, what, and why so called, iii. 242.Drawing, an Observation for- taken from the GartersGbscura ,. iii. 83 n.

Drop, spherical of falling Rain- Phænomena of Reflec-tion and Refraction in, illustrated, ii. 355.

Drops of Glass, the Phænomena accounted for, i. 38 n.Duplicate Ratio, what, i. 7 m

E

If AR, curious Structure of, described, ii. 2T9 n *J '~ i How Sounds are excited in the Mind, ii. 222 n*iiart-k, with its Moon, mean Distance of, iii. 116. I tsPhasts as appearing from the Moon, iii. 122 n.True Figure of demonstrated, iii. 142 n. &sDEarth’s Orbit, why elliptical, iii. 144 n.

Earth’s third Motion represented by an Orrery, n ,;169 n. Remarkable Phænomena, from the Motionof its Axis, iii. 170 n. & fig. Conical Motion ot