Extcnftve Lcgartihinic and Tr'igommetrical Tables. 313 



of" this work. It is much to be wiflied, that the government would refume the impreflion 

 of this immenfe work, which was fufpeiuled at the fall of the affignats. 



To the notice, of which we have given an account, Cit. Prony has added a bibliographic 

 anecdote refpe£ling the Opus Palat'mum, very interefting to thofe who feek rare books. 

 They will learn with pleafure, that there are a few copies of this book, in which 86 pages 

 have been reprinted, containing the co-tangents and co-fecants of the feven firfi: degrees, 

 of which the laft figures were uncertain in the firft copies, and which Pitifcus could not 

 correft, but by carrying the fines of thefe degrees "to twenty-two decimals, which had 

 been calculated only to fifteen. 



This note is followed by the report of Citizens Lagrange, Laplace, and de Lambrc, re- 

 fpetling thefe tables, In which we find various Interefting details on the conftruflion of 

 trigonometrical tables In general, and the methods employed by one of the Commiffaries 

 to verify thofe which were fubmittcd to them. 



BtilleUn de Science, No, j2, An ()i 



VIL 



Ohfervations relative to the Means of Increaftng the Quantities of Heat obtained in the Com- 

 bujlion cf Fuel. By Count Rumford *. 



I 



T is a fa^l wlilch has been long known, that clays, and feveral other incombuftible fub- 

 ftances, when mixed with fea coal, in certain proportions, caufe the coal to give out more 

 heat in its combuftion, than it can be made to produce when it Is burned pure or unmixed } 

 but the caufe of this increafe of heat does not appear to have been yet inveftigated with that 

 attention which fo extraordinary and Important a circumftance feems to demand. 



Daily experience teaches us that all bodies, — thofe which are incombuftible, — as well as 

 thofe which are combuftible, and aftually burning, throw off in all direftions heat, or 

 rather calorific (heat-making) rays, which generate heat wherever they are flopped, or ab- 

 forbed ; but common obfervation was hardly fulBcIent to fhew any perceptible difference 

 between the quantities of calorific rays thrown off by different bodies, when heated to the 

 fame temperature, or expofed In the fame fire ; although the quantities fo thrown off, might 

 be, and probably are, very different. 



It has lately been afcertained, that when the fides and back of an open chimney fire- 

 place, in which coals are burned, are compofed of fire-bricks, and heated red-hot, they 

 throw off into the room Incomparably more heat than all the coals that could pofiibly be 

 put into the grate, even fuppofing them to burn with the greatefl pofTible degree of bright- 



* Journal of the Royal Inftitution, p. 28. 



Vol. V. — NoyEMBER, 1801. Ss nefs. 



