[ 6 33 ] 
€igma (Mr.), his opinion concerning air in the blood, p. 233—236. 
Circle , a new and general method of finding fimple and quickly-converging ferics ; by 
which the proportion of the diameter of a circle to its circumference may eafily be 
computed to a great number of places of figures, p. 476 Excellence of this method 
in the fimplicity of the feries by which an arc is found from its tangent, p. 477. 
Clayton (Mr. William), his account of Falkland lllands, p.99. See Falkland Ijlandu 
Cleanlinefs , and plenty of frefh water, will prevent the fcurvy amongft feamen, p. 
405. 
Clouds , attra&ed by lofty mountains, p. 296. Eleftrical experiments made on the 
clouds with a kite, p. 407 — 41 t. 
Compafs, the variation of the, containing 1719 obfervations to, in, and from, The 
Eaft Indies, Guinea, Weft Indies, and Mediterranean, with the latitudes and lon- 
gitudes at the time of obfervation, p. 18. Letter from William Mountaine, Efq. 
concerning thcfe obfervations, p. 18. &c. Dr. Halley’s recommendation of them, 
p. 21. When and where the obfervations were made, p. 23. Explanation of the 
tables, 23, 24. The number of compaffes ufed, and by whom managed, p. 24. 
The variation of the compafs to, in, and from, The Eaft Indies, on board the Lyon, 
in the years 1721, 1722, 1723, and 1724, p. 25—3:4. In a voyage to Guinea, Weft 
Indies, and back to England, in the Kinfale, in the years 1725, 1726, and 1727, 
p. £5 — 68. From Madeira to the Weft Indies, in the Lark, in the years 1727 and 
x 7 2-g-, p. 69. In going towards Lilbon from England, and in the Mediterranean, on 
board the Dreadnought, in the years 1730 and 1731, p. 70. In the Mediterranean, 
on board the Heflor, in the years 173 3, 1 7 3 4 » an< ^ * 735 ’ P' 7 1 * 7 2 * 
Compafs , concerning the variation-compafs belonging to the Royal Society, p. 205— 
395. Obfervations made with it, p. 392, 393. 
C 00 k (Capt. James), his account of the method taken for preferving the health of the 
crew of his majefty’s fliip the Refolution, during his late voyage round the 
world, p. 402. See Health. Extra-ft of his letter, concerning the rob of lemons 
and oranges being furnilhed in fea -voyages, p. 406. Of opinion that fmoak and 
fire purify a (hip much better than vinegar, ibid. On the tides in the South Seas, p. 
447. See Tides. 
Copper , a difference in its weight when hot and cold, p. 510. 
Com, the manner of treading it out at Stellenbofch, in the fouthern part of Africa, 
Crimping of filh, cutting them into pieces while alive, why praftifed, p. 415. «. 
Gry/lallizaticns, on thofc, obferved on glafs, p. 53 °. Different cryftalhzations in glafs ac- 
cording to the circumftances with which their concretions have been accompanied, 
P r,j_ coq. This quality in glafs to cryftallize favours the opinion that the great 
native cryftals of ba/a/tes have been produced by (he cryftallization of a vitreous la,a, 
rendered fluid by the fire of volcanoes, p. 539 54 “' 
Days, 
