150 Mr H. Meikle's Refutation of Mr Ivory's Nezv Law of 



my previous labours on the same subject in No. II., had already 

 set a-working the great powers of Mr Ivory. But, on perusing 

 the numbers for February and March, of that valuable united 

 journal The PMlosophical Magazine and Annals of Philosophy, 

 I found an attempt to bear down, not by rational argument, but 

 purely by force of his own authority, all that I had formerly 

 proved on this subject. I say pj'oved ; for, although Mr Ivory, 

 throughout his recent papers, is at great pains to state^ in the 

 most pointed terms, the very reverse of what I had inculcated ; 

 yet he not only does not combat my reasoning, but admits, in 

 the strongest terms, nay, eulogizes, in one place or other of his 

 paper, all the data I have employed ; and every one who has 

 but a moderate acquaintance with the mathematics, will see that 

 the conclusions I have drawn follow as necessarily from the data, 

 as those of any proposition in Euclid. A still more elementary 

 investigation of the law of temperature in air, is given at page 

 SS6. of the last Number of this Journal ; and the same conclu- 

 sions may be legitimately drawn from the premises in various 

 other ways. 



I did not expect that on this subject I was to be opposed by 

 first rate mathematicians ; because such ought to see at once the 

 truth of my conclusions, even although they may not admit my 

 investigations to be altogether free from imperfections. Others 

 are at hberty to withhold their assent, but men of science must 

 give way, because it is not a mere matter of opinion. There is 

 no alternative, if the data be admitted. 



Mr Ivory's paper is entitled, '* Investigation of the Heat ex- 

 tricated from Air, when it undergoes a given Condensation."" In 

 the Philosophical Magazine for July 1 825, the same author has 

 given us what he calls " The Laws of the Condensation and Di- 

 latation of Air," &c. and which are intended to serve the very 

 same purpose. They had been published two years prior to 

 this, by that distinguished mathematician M. Poisson. But, in 

 the present article, no mention is made of the old laws, far less 

 whether they are now repealed to make room for the new. When 

 an author presents the public with a view^ of any subject, diiFer- 

 ent from, or directly opposed to, what he had formerly given 

 them, h^ is not only expected, but bound, in good faith^ to state 



