INDEX. 



{Juartz and filex, their difference, 89, 93 



R. 



.Rabbits, ufe of their whifkers, 154 



Rags, bleached, 119 



Rail- roads, general fyftem of, by R. L. 



Edgeworth, Efq. 221 

 Razor, to chufe a good one, 47.— To 



fharpen, 48. — On the choice and ufe 



of, sio— -Why it cuts better when 



heated, 211 

 Reflection, circles of, 4 

 Rhades, 34 

 Ribaucour, 119 

 Ridges, or elevations in the luminous 



matter of the fun, 17 

 Rollo, Dr. 204 

 Round, Mr. 104 

 Royal Society, tranfadtions of, 73 

 Ruler, plain graduated, its ufe for per- 



fpeclivc, 2S4 

 Rumford, Count, 81, 165 



Schroeter, Mr. of Lilienthal, his obferva- 

 tions on the new planet Ceres with his 

 great telefcope — denfe atmofphere — 

 fufpicion of two fatellites, 318 



Scott, Mr. 68 



Seafons, how far influenced by the changes 

 in the fun itfelf, 20 



Sebacic acid, Thenard on, 34 



Seeberg obfervatory, 288 



Segner, 34 



Senebier on the influence of air in vegeta- 

 tion, 157 



Seybert, Adam, 151 



Shallows, in the folar luminous clouds, ib. 



Shaving, art of, 47 



Sheldrake, Mr. on the nature and prepa- 

 ration of drying oils, with a view to 

 the improvement of fuch as are ufed as 

 vehicles for painting, 259 



Shocks, galvanic, 180 



Silex and quartz, their difference, 89, 93. 

 — Ignarius, 89 



Sloane, Sir Hans, 52 



Society of arts, 251 



Socquct on calorie, 76 



Soda, hidrofulphuvet of, its cryftals by 



Vauquelin, 303 

 Soldier, Prouft on the fubfiftence of, 100 

 Sound, mufical, produced by burning hi- 



drogen, 129 

 Steam engines, recommended for drawing 



carriages, 223 

 St. Genis, 157 

 Stodart, Mr. James, ferioufly affected by 



breathing the nitrous oxide, 225 

 Spar, adamantine, found in America, 151 

 Spider's wax, 299. — Webs inftead of the 



crofs wires in the foci of telefcopes, 319 

 Spirit level, its limits of accuracy, by Mr. 



Ez. Walker, 309,-312 

 Sugar, its effect in ink, 147 

 Sulphurets, native and artificial of iron, 



by Prouft, 269. — Metallic, their na- 

 ture explained by Prouft, 109 

 Sun, Herfchel's obfervations on its nature, 



13. — Sufpefted to have a bright and a 



dark fide, 21 



Telefcopes, darkening apparatus for, by 

 fluids, 224 



Tellurium, afferted to be the metal anti- 

 mony only, 234 



Thenard, Cit. on febacic acid, 34, 238 



Thomfon, Dr. Tho. on the fuppofed 

 currents in hot liquids, 81 



Thunder, remarkably well imitated by a 

 fheet of iron, 149 



Tin, fuming muriate of, improved pre* 

 paration of, 117 



Tranfa&ions, philofopbical, 73 



Tranfitinftrument, comparative excellence 

 of the plumb line and fpirit level with 

 regard to it, and adjuftment, See. by- 

 Mr. Ez. Walker, 309, 312 



Trenethick wood tin mine, 165 



Trevithack. Mr. his powerful engine for 

 raifing water by preffureof a column in- 

 clofed in a pipe, 161 



Tromfdorff, Profefftr, on a new mineral 

 refemblin* 



