17 '2 French National Instil u/c. 



*lep;irtmcnt of mechanical and physical science. The se- 

 cond volume will contain, in the first place, the mathema- 

 tical elements ot" natural philosophy deduced from first prin- 

 ciples, and in many instances extended by new investiga- 

 tions : secondly, a methodical catalogue of works relatmg 

 to natural jjlnlosophv and the arts, with about ten thousand 

 references to particular memoirs and passages, and a num- 

 ber of useful tables, and of concise abstracts and remarks : 

 and lastly, a collection of the author's miscellaneous papers, 

 reprinted, with Siome alterations, principally from the Phi- 

 losophical Transactions. The work is expected to be com- 

 pleted early in the next winter. 



XXVII. Proceedings of Learned Societies. 



FRENCH NATIONAL INSTITUTE. 



j4n Account of the Lalours of the Class of the Mathema- 

 tical and Physical Sciences of the French National Insti- 

 tute from the 2(Jth of June 1604 to the same Day 1S05. 

 By M. CuviER, perpetual Secretary. 



PHYSICAL PART. 



Almost all the sciences which engage the attention of the 

 society have this year made curious and important acquisi- 

 tions ; and, as is usual, chemistry has obtained the most 

 considerable and most numerous. 



Count Rumford has examined heat under a new point of 

 view. He has endeavoured to determine the force of the 

 solar rays to produce it. The degree to which it is carried 

 when its rays are; concentrated by means of a burning glass 

 is well known : but i« their real power thereby augmented? 

 or does the effect arise from their acting in greater number 

 on a smaller space ? To ascertain this, count Rumford in- 

 vented a reservoir of heat, which is nothing else than a 

 metal vessel filled with water having a thermometer im- 

 mersed in it : it receives the solar ravs on one of its faces, 

 which is blackened, and the water it contains acquires a 

 ■certain degree of heat. Count Rumford suffers these rays 

 to arrive sometimes in a parallel direction and sometimes 

 ■concentrated by a magnifying glass ; but bringing the latter 

 nearer or making it recede in such a manned that the rays 

 shall strike on a greater or less space of the surface of the 

 vessel, though thcLr quantity continues always the same. 



Tlve 



