[ «7 ] 
Hunter , Dr. Allay of fevcrat ores in his mufeum, p. 327. 
Hygrometer . Obfemtions with Mr. Smeaton’s, p. 167 — 173, 
I. 
Jafper s, how formed, p. 25. 
Iconantidiptic . See 9 " de/cope. 
Incruftation , a particular one defcribed, p. 41. How formed on the windows of 
Ruffian houfes, p. 326. Dangerous effects of fuch, ibid. 
Inundations . See Rivers. 
Iron , and its folutions, contribute to haften and promote theprogrefs of the concretion 
and induration of flone, whenever they meet with cementing cryftalline particles, 
which abound in fea-water, p. 38. Any induration, or petrefa&ion of matter, 
much haftened, and the confolidation rendered much more compleat by being near 
a mafs of iron, flill more by the admixture of any folution of that metal, p. 39. 
Confirmation of this do&rine by three inftances, p. 40, 41. 43. 43. Dr. fothergill's 
conjectures on this fubjeft, p. 47. Common fea fand, with a fmall mixture of the 
folution of iron, may become a very ufeful flone, p, 48. 
Iron fpathofe ores, account of, p. 29. 
Jupiter . Eclipfes of the fatellites of, obferved at Cork, p. 163 — 177. At Green- 
wich, p. 179. . i . o i 1J 
r •, : - if , / r.i . thi ;0 Mvl 
L. 
Labrador eft one, account of the, and of allum made with it, p. 23. 
Lead. Account of the white lead ore, p. Z9. Tobacco-pipe duly prepared, propofed 
to be ufed by painters inflead of white lead, p. 20. 
Lenfes , a concave, and a convex, applied before the objeft-glafs of the telefcope of 
the equatorial inltrumenf, to correct the errors arifing from the refraction in alti- 
tude, p. 3 33. 
Level. Spirit level fixed to the equatorial inflrument, its ufes, p. 334. 
Levels. General and eafy methods of taking them through large extents of countries 
where rivers pafs, p. 643. - 
Life. Difference in the modes of reftoring to it thofe who are deprived of it by 
water, and thofe who have loft it by the fumes of charcoal, p. 329. 
Lightning. Its effedls on board the Atlas, p. 160. Struck the main- m aft head, 
defcended down the rigging, and entered the gun-deck, ibid. Man ftruck 
dead fey, p. 16 1. No damage done to the fhip, mails, or rigging, nor any vifible 
track oTthe lightning to be found on the mafts, ibid. 
Loadstones , artificial, how made by Dr. Knight, p, 51. 
4U 2 
Macrocafon. 
