I! 1 
of forming the brafs -grinding tool, p. 506, 307. How to form the bed of hones, or 
the third too}, p. 307, 308. The manner of forming the bruifer, p. 308, 309. How 
to procure walhed emery for the working of thefe tools, p. 309. Of grinding the 
fpeculum, the brafs tool, and the bruifer together, p. 3C9 — 31 1. The manner of 
figuring the metal upon the hones, p. 31 1 — 316. Remarks on Meflrs. Hadley and 
Molyneux’s method of polifhing the fpeculum, p. 318 — 320.. Experiments which 
led to a certain and eafy method of giving an exquifite polifh, and a correft para- 
bolic figure to the metal at the fame time, p.321 — 327. How to polifh the fpe- 
culum, p. 327—333. How to give the parabolic figure to the nuetal, p. 333 — 333. 
To try the true figure of the metal, p. 338 — 341. Farther remarks on the procefs 
of polifhing the fpeculum, p. 34: — 343. Teff of a good telefcope, p.343,344. 
Sir Ifaac Newton firft propofed the polifhing with pitch, p. 344. Suppofed to be 
the only fubllance in nature that is perfe&ly calculated for that purpofe, p. 343. 347. 
Procefs for polifhing the little fpeculum, ibid. A new method of foldering the piece 
of brafs to the back of the little fpeculum, p. 346. Explanation of the figures on :he 
plate, p. 348, 349. 
' Theory . Anew theory of the rotatory motion of bodies afTefled by forces di&urbing 
fuch motion, p. 26 6. 
Thermometer, flate of it at Lyndon in Rutland, during the year 1776, p. 350. State of 
it without and within in London, for each month throughout the fame year, 
p, 358 — 38 1 . Greateft, lead, and mean height in each month, p. 382. The report 
of the committee appointed by the Royal Society to confider of the bell method of 
adjufling the fixed points of thermometers ; and of the precautions neceflary to be 
ufed in making experiments with thofe inflruments, p. 816. The quickfilver in the 
cube and in the ball fhould be of the fame heat, and the ball not immerfed deep irr 
the water, p. 818.833. Method of obtaining thefe requifites, p. 8 13. Experiments 
to determine the boiling point of thermometers, p. 8 r 8 — 8-33. Cf the difference of 
expanfion of the glafs tube and the fcale, p. 834. Concerning the correction necef- 
lary to be made when the quickfilver in the tube is of a different heat from that in 
the ball, p. 833 — 844. Rules to be obferved in adjufting the boiling point, p.845— 
853. On the freezing point, p.856, 857. Precautions neceifary to be obferved in 
making obfervations with thermometers, p. 857-. 
Thibet, or Bout an, an account of the kingdom of, p. 465. Hardly known to Euro- 
peans, ibid.. Its fituation, p. 466-. The war which led to a farther difeovery of this- 
country, p. 467. The Europeans and Beutaners firft meet at the attack of Cooch- 
Behar, ibid. Both greatly furprized at meeting with fuch a race of men, p. 467* 
468. The Boutaners conquered by the Europeans, fue for peace, p. 468. The 
governor of Bengal grants a peace* and enters into a treaty of commerce with 
them, p. 468, 469, Defcription of the country, p.469 — 471. Of the inhabitants, 
p. 470. 472. Their= drefs, p„ 472. Food, p. 472, 473. Their religion and pedi- 
