INDEX. 



Pi&et, 23, 280 



Piggott, Mr. 143 



Piftol, magazine, defcription of, 250 



Planets, gene, al definition of, 128 



PJants, wax-bearing, 187. — On the dif- 

 femination of, 253. — On the fecuia of 

 green, 273. — Fibrous matter of, 274 



Plafter cement, 60 



Plunger, method of raifing or lowering 

 veflels on canals by means of, 236 



Pneumatic apparatus, improvement in 

 Read's, 6 — Woulfe's invented by Glau- 

 ber, ib. 



Porta, 197 



Powel, Dr. 137, 138 



Powers refractive and difperfive, method 

 of examining by prifmatic reflection, 89 



Prieftley, Dr. on phlogifton, 65 



Primaeval mountains, 262 



Primary colours of the prifmatic fpectrum 

 only four, 98 



Printing, origin of, 69 



Prifm, its ufe in examining the refractive 

 and difperfive powers of bodies, 89. — > 

 Square one to be preferred, 90 



Prifmatic fpectrum confifts of only four 

 primary colours, 98 



Prize quefHons, 278 



Production of colours, fame new cafes of, 

 180 



Prouft on the fecuia of green plants, 273. 

 — On the fugar of grapes, and on uree, 

 280 



Pyrites ufed 11 ftead of flints in old fire- 

 arms, 103 



Quadrant, Mr. E. Walker's reflecting, 



218 

 Quern, or Scottim hand-mill, 220 

 Queftions, prize, 278 



R. 



Rain, experiments and obfervations on, 

 159. — Annual quantity fallen in Eng- 

 land and Wales, 160. — Mean quantity, 

 161.— In Paris, 173 



Ramond fucceeds in reaching the fummit 

 of Mont Perdu, 207 



Ramfden's eye-glafs micrometer defective, 

 117 



Raphael, 234 



Rafhlfigh, Mr. 209 



Rays, invifible heat-making, 99,— Dif- 

 oxigenating, 100 



Read, Mr. improvement in his pneumatic 

 apparatus, 6 



Rees, Dr. 135 



Reflecting quadrant, Mr. E. Walker's, 

 218 



Refraction of the light of candles and of 

 electricity, effects of the, 100. — Ob- 

 lique, of Iceland cryftal, 148.— Dif- 

 perfion of colours by, 185 



Refractive powers, method of examining 

 by prifmatic reflection, 89.— Table* of, 

 93> 98 



Refrangibility, aberrations of, how cor- 

 rected, no 



Reynier, Cit. L. on the diffemination of 

 plants, 253 



Rivers, quantity of waters carried off by, 

 159.— Method of determining the quan- 

 tity that flows through, 164 



Rochon, his memoir on achromatic glaffes, 

 no 



Roi, Col. 32 



Rouelle, Hilaire, 273 



Rumford, Count, 56. — His experiments 

 on fluids as conductors of heat, 75.— 

 Not conclufive, 76 



S. 



Saint- Victor, Cit. his machine for root- 

 ing up the flumps' of trees, 243 

 Salts generated in cheefc, 277 

 Sapphire, analyiis of the, 10 

 Satire, organ oi the talent for, 234 

 Sauer, 106 ! 



SaufTurc, 34 



Secret writing, methods of, 246 

 Seeds, prefervation of, 255 —Advantages 



offteeping, 281 

 Seguinj 222 



Self- 



