Scientific Intelligence. — Natural Philosophy, 391 



survey of Clare Island, on the west coast of Ireland, illustrat- 

 ing the same by maps and sections executed by Mr Bald. 



The Professor then gave a general descriptive account of a 

 splendid series of the Pheasants and Peacocks of India, speci- 

 mens of which were placed on the table. A stuffed specimen 

 of a Persian Sheep, presented to the Royal Museum by James 

 Gibson Craig, Esq. was also exhibited. Mr Audubon laid be- 

 fore the meeting several specimens of the coloured Plates of his 

 great work on American Ornithology, executed by Mr Lizars 

 of this city ; and they excited general admiration. 



SCIENTIFIC INTELLIGENCE. 



NATURAL PHILOSOPHY. 



1. Repulsion of Heat inversely as the square of the distance. 

 — Sir Isaac Newton has shewn, Principia, Lib. ii. Prop. 23 *, 

 that if the repulsion between the particles of a gas were inversely 

 as the square of the distance of their centres, the cube of the 

 pressure would be as the fourth power of the density, and vice 

 versa. Now this is precisely the relation which we formerly 

 saw should subsist between the pressure and density of air con- 

 taining a constant quantity of heat, if, as appears from experi- 

 ment, the specific heat under a constant volume be to that under 

 a constant pressure as 3 to ^-f- ; and, therefore, whilst the quan- 

 tity of heat connected with each particle of air is constant, the 

 repulsion between them is inversely as the square of their di&. 

 tance J. This being the law common to magnetism and gravita- 

 tion, scarcely leaves a doubt that the true ratio is that of 3 

 to 4. It is also the actual law of gaseous repulsion ; for that 

 first given by Newton, and generally adopted, making the re- 

 pulsion inversely as the simple distance, really compares the re=. 



* Some allege that this proposition requires each particle to act only on 

 those next it ; but it holds equally true, whilst each acts on a constant nuna- 

 ber, however great, if similarly situated. 



t See equation (C) page 336. vol. i. of this Journal. 



t Any tendency in the particles to gravitate toward each other, would not 

 afifect a ^iw similar to its own. 



" ■"■■ cc2 



