C 3 
T. 
Tartar of vitriol Mr. Beaume miftaken, in averting that he obtained it from the blue 
Argilla, p. 20. 
Telefcope, Account of an iconantidiptic telefcope, producing two images of the objed, 
the one in a dired pofition, the other reverfed, p. 130. The dired pafiage of the 
center of a liar obferved with this inftrument, p. 131. The difficulty of illumi- 
nating the threads of the telefcope obviated by this method, ibid. Why CafTe- 
grain’s conftrudion of the refleding, is preferable to either the Gregorian or New- 
tonian, p. 426. 
Thermometer . Defcription of one, for making experiments on the heat of boiling- 
water, p. 360. Table for the ufe of artihs who make them for fuch purpofes, 
p. 375. Regifter of the, at Lyndon, for 1778, p. 545. Obferved at Nain and 
Okak, p. 658. 
Tin , fufceptible of a confiderable degree of magnetifm, p. 543. 
Tin-fpar of the Germans, experiments upon it, p. 26. 
Tobacco-pipe , duly prepared, propofed to be ufed by painters inftead of white-lead, p. 20. 
Tobacco-pipe clay . Allum may be produced from, p. 19, 
U. 
XJgar , what it is, and its eiFeds, p. 327. 
Vitriolic acid y more of it in gypfum than in felenitical fpars, p. 17* 
Ulna . Treatment of a difeafe of the lower part of the, where it joins the bones of 
the carpus, p. 10. 
W. 
Water* Firft application of cold water to the human body produces heat, p. 330. The 
variation of the temperature of boiling, examined, p. 36 2 * That the heat of boiling, 
is variable, known to Fahrenheit, ibid. Becilive experiments by Le Monnier and 
Caffini, to Ihew that this quantity is very variable, p. 363. Mr. Be Luc’s oblervations 
on this fubjed, repeated by Sir George Shuckburgh in a journey over the Alps, p. 364. 
And again in 1778, p. 363 — 367. True proportion of thepreflure of the atmofphere, 
how obtained, p. 370. Sir George’s obfervations compared with Mr. Be Luc’s, 
and with each other, p.371 — 373. Water, which has Hood feme time expofed to 
th© 
