570 
I N D E X. 
Tenckrdefi, in Kent, an account of the effefts of lightning on a honle there, which wa* 
furnilhed with a pointed conductor, p. 336. See Lightning. 
Teneriff, Pic of, conjedlures concerning, p. 50. 
1 ' H E O R E M S, mathematical. 
Thcorema I. Si linea refta arcum circularem contingentibus duabus interceptum contingat, 
fegmentum ejus, contingentibus primo pofitis interceptum, in contadtus fiii punfto 
vel ^qualiter vel insqualiter divifiim eft, prout arcus ipfe circularis aequaliter vd in- 
acqualiter in eodem pundo divifuseft. Segmentaque arcus (ina'qualiter fcilicet divifi) 
et redhe contingentis majora et minora ab iifdem funt partibus inutui contach’is, 
p. 301, 30Z. 
II. Linea reda quee arcum circularem contingentibus duabus interceptum in pundo 
medio contingit, & contingentibus primo pofitis hinc inde occurrit, minima eft om- 
nium qua?, eundem arcum contingentes, contingentibus primo pofitis Intercipiuntur, 
P- 303—306. 
III. Polygonorum omnium, lateribus numero datis, datum circulum circumfcribentium, 
iequiaugulum perlmctro minimum eft, p. 306 — 308. 
IV. Polygonorum omnium, lateribus numero datis, datum circulum circumfcribentium, 
aequiangulum area minimum eft, p. 308. 
V. Polygonorum omnium, lateribus numero datis, dato circulo inferiptorum, aequila- 
terum perimetro maximum eft, p. 308. 
VI. Polygonorum omnium, lateribus numero datis, dato circulo Inferiptorum, cequila- 
terum area maximum eft, p. 310. 
Theorems. Two for the folution of polygons, p. 28 1, 282. 
Inveftigation of a general one for finding the length of any arc of any conic hyperbola, 
by means of two elliptic arcs, p. 283 — 286. Some other new and ufeful theorems de- 
duced therefrom, p. 286 — 289. 
An equilateral triangle inferibed within a circle, larger than any other triangle that can be 
infcribed within the fame circle, p. 296 — 298. 
An equilateral triangle defcrlbed about a circle, lefs than any other ttiangle that can be 
deferibed about the fame circle, p. 298. 
The fquare of the fide of an equilateral triangle Infcribed In a circle, equal to a red- 
angle under the diameter of the circle, and a perpendicular let fall from any angle of 
the triangle upon the oppofite fide, p. 299, 300* 
T‘heophraJius, an alTertor of the moon’s influence upon the weather, p. 189. 
T’hermometer, ftate of it at London throughout the year 1774, p. 140 — 164. — At Lyndon, 
In Rutland, p. 199. — At Chiflehurft, In Kent, p. 294. 
Thermometer., kept within doors, a very indifferent meafure of the heat of any climate, 
p. 202. The leaft and greateft heights of the thermometer at Allahabad in each month, 
p. 203. State of the thermometer between Mdrafs and the Southern Tropic, p. 204. Its 
ftate from thence to about 15* E. of the Cape of Good Hope; to St. Helena; to 
lat. 
