SCIENTIFIC NEW^. '141 



is the lefs Turprjfing that the difference fliould be fo fmall, as 

 the dimenfions of the coloured rings do not by any means vary 

 at the violet end of ihe rpe<5lrum, jo rapidly as at the red end. 

 ^ ;For performing this experiment wilh very great accuracy, a 

 heliollale would be neceffary, ftnce the molion of the fun 

 .caufes a flight ch.ange in the place of the image; and leather, 

 impregnated with the muriate of filver, would indicate the 

 efte6l with greater delicacy. The experiment, however, in 

 its prefent (late, is fufficient to complete the analogy of the 

 jnvifible with the vitible rays, and to (how that they are 

 equally liable to the general law which is the principal fub- 

 je6l of (his Paper. If we had thermometers fufficiently deli- 

 .cate, it is probable that we might acquire, by (irailar means, 

 information dill more interefiing, with rei'ped to the rays of 

 invifible heat difcovered by Dr. Herfchel; but at prefent there "*' 



is great reafon to doubt of the pra6licability of fuch an expe- 

 riment. 



SCIENTIFIC NEWS, ACCOUNT OF BOOKS, Syc, 

 National Injiitute. 



i- HE clafs of mathematical and phyfical fciences of tbe National Infti- 

 French National Inftitute had a public fitting on the 6th Mefli> ^''^^ P*"''"* 

 dor (June 25.) The fubje^ts appointed for prizes were the 

 following; 



Mathematics. " It is required to give a theory of the per- Planet Pallas, 

 turbations of the planet Pallas, difcovered by M. Olbers.** 



The prize will be a gold medal, weighing one kilogramme, 

 '(35^oz. avoirdupois.) 



Natural Philofophy. The clafs had propofed for tTie fubjefi Carbon in vegc- 

 of a prize the following queftion. '* To determine by expei-i- 

 ment the different fources of carbon in vegetables.'* The 

 concurrence is prorogued until the 1ft Germinal in the year 13 

 (March 22, IS05.) 



Tlie concurrence for the prize upon the following queftion Torpid ftate of 

 is alfo prolonged to the fame period. *' To determine by ana- *^^'.?P**^'^* ^^* 

 toraical and chemical obfervations and experiments, what are ' 



the phenomena of the torpid ftate to which certain animals* 

 fuch as marmots, dormice, &c. are fubjed during the winter, 

 with refpedt to the circulation of the blood, refpiration, and 

 irritability ; to inveftigate the caufes of this fleep, and why 

 it is peculiar to thefe animals.'* 



The 



