400 Intelligence and Miscellaneous Articles. 



M. Eegnault found 3-409. 

 Eor ethylene I obtained 



0-3950 



0-4070 



Mean .. 0-4010 



M. Eegnault gives 0-4147 and 0-3933, mean 0-4040. In two 

 other experiments, on this last gas adulterated by mixture with a 

 little air, I found 0*3850 and 0-3750 — that is to say, a value too 

 low, as was to be expected. 



The accordance between these experiments and M. Eegnault's is, 

 we see, very satisfactory. I will give, in a subsequent memoir, a 

 more exact and detailed description of the method, with a discus- 

 sion of the process and the way to eliminate the causes of error. I 

 am at present occupied in extending the experiments to other gases, 

 purposing to study especially the influence of temperature on the 

 specific heat of gases and vapours. — Bibliotheqiie Universelle, Archives 

 des Sciences, vol. li. pp. 73-76. 



ON A NEW FORMULA IN DEFINITE INTEGRALS. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 Will you allow me a few lines to say that the very considerable im- 

 provement effected by Mr. O'Kinealy (Phil. Mag. for Oct. pp. 295, 

 296) in the method of proving the formulae given in the July Number 

 (viz. by replacing the series by a finite expression involving the 

 symbol of operation E) was remarked by me almost as soon as my 

 paper was published, and that, after developing the method so far 

 as to include these formulae and several others, I communicated it, 

 with the examples, to Professor Cayley, in a letter on the 22nd or 

 23rd of July, w T hich gave rise to a short correspondence between 

 us on the matter at the end of July. My only reason for wishing 

 to mention this at once is that otherwise, as I hope soon to be able 

 to return to the subject and somewhat develop the principle, which 

 is to a certain extent novel, it might be thought at some future time 

 that I had availed myself of Mr. O'Kinealy's idea without proper 

 acknowledgment . 



I remain, Gentlemen, 



Yours faithfully, 



J. W. L. GrLAISHER. 



Trinity College, Cambridge, 

 October \874. 



