A, 
564 I N D E 
Retina, of the eye what ffroke it may fufiain, p. 439, 440. 
Robert [on , James Efq-, his dcfcription of the blunt- headed 
cachalot, p. 321. 
Robertfcn , Mr. John, his letter on cafes of compound 
intereft, p. 508. 
Roots of equations, howdifcovered univerfally, p.241, 242. 
Rofe , Cap:. Alexander, his obfervaiicns made in theEaffc 
Indies, p. 444, 445. Obferves the tranfic of Venus at 
Phefabad, p. 450. 
Rowning, Rev. Mr. his machine for finding the roots of 
equations, p. 240. 
S. 
Salt faring, how to eftimate the weight of fait which it 
contains, p. 350. 
Salts , whether they fill the pores of water, without in- 
creafing its volume, p. 327. Experiments proving 
the contrary, p. 328, &c. Fable of the elevation of 
water by the abforption of different falts, p. 330, 
331. Specific gravities of feveral, p. 336, 337. Gravities 
of faturated folutions of various fairs, d. 545, 346. 
Of folutions with a given quantity of thefe, p. 347. 
And of different quantities of the fame fait, p. 348, 149. 
Seawater , meafure of its ftrer.gth, p. 350. 
Segner , Mr. John Andrew, his method of difcovering 
the roots of equations, p. 240. Its defeft, p. 241. 
Selvofa or woody region of mount Etna, covered with 
large trees, p. 8. Furnifhes timber to Naples, as it 
did to ancient Syracufe, p. 9. 
Semen badian , the feed of the Illicium, ufed in medicine. 
p- 52 5, 53 1 * 
Serum or the blood deferibed, p. 368. Different from 
the coagulable lymph, p. 371. Requires a greater 
heat to coagulate, p. 385. 
Smith, Dr. William, obfervations of a tranfit of Mercury 
at Norriton in Pennfylvania, p. 504. 
Snow 
