124 Mr. Meikle on the 



terrestrial radiation is diminished willhe projwrtionally warmer ^ 

 drier, of a more equable temperature, and more healthy. 



We have been given to understand that this enquiry will be 

 resumed by our author in a paper, which will shortly appear in 

 one of the scientific periodicals. 



On Mr. Ivory's Investigations of the Velocity of Sound. 

 By Henry Meikle. 



In the article on sound inserted in the Edin. Phil. Jour, for 

 October, 1827, I had acquiesced in the theory of the late cele- 

 brated Marquis Laplace, so far as it appeared to go, and only 

 suggested some small additions to it. But since writing that 

 article, I have examined more closely the investigation of that 

 eminent mathematician, given in the Conn, des Tems pour 

 I'an 1825, and Mecanique Cdeste, torn. v. page 119, and am 

 now convinced that it is in itself objectionable in several re- 

 spects, independently of any thing which I formerly hinted : 

 so that my proposed amendments on this theory are as nothing 

 compared with the thorough reform it would require ; the 

 result being neither deduced from correct principles, nor by 

 means of an accurately managed calculus. The like objec- 

 tions attach to Mr. Ivory's view of it, given in the Phil, 

 Mag. for July, 1825, p. 11. To this I shall principally 

 direct my remarks at present, because it is better known 

 in this country, and is given in a more detached form than that 

 of M. Laplace, which, though essentially the same, and, in 

 fact, the groundwork of the other, is curiously interwoven with 

 some untenable speculations regarding heat*. 



Considerable obscurity pervades Mr. Ivory's investigation, 

 especially in laying down the first principles, which are both 

 inconsistent and defective. Several of the most important 

 circumstances are overlooked altogether ; but, as will be seen 

 from extracts which soon follow, the leading idea by which the 



* In the Conn, des Terns for 1826, M. Poisson has treated the subject 

 in a more general way, with the view of embracing cases where the me- 

 dium is not uniform. The length of his Memoir would render it tedious 

 fully to discuss its merits; but, so far as regards the ordinary case of 

 sound traversing the horizon, it is not materially different from that about 

 tp be examined. 



