ON THE STRUCTURE OF CALCULI. 35 



ttlso small, are commonly some of them equal to y, m or Reply to Mr. 

 unity; let him take a larger number, for example 1520, and oug ' 

 resolve into squares; now e~ 1520, y sz 1444, and t zz 19 m; 

 .whereas his demonstration does not include numbers higher v , 

 than those of the form e zz y -f 2 m. 



It is not my intention to pursue this argument any far- 

 ther, because however curious the theorem may be as relat- 

 ing to the indeterminate analysis, it is perhaps uninteresting 

 to the greater part of your correspondents. If therefore, 

 Mr. Gough undertake to answer this question, I shall leave 

 it for your mathematical readers to decide for themselves, 

 how far it may be considered as satisfactory. 



Yours, &c. 



Royal Military Academy, P. BARLOW. 



Dec. 9, 1808. 



VII. 



A Letter on the Differences in the Structure of Calculi, 

 which arise from their being formed in different Parts 

 of the Urinary Passages; and on the Effects that are 

 produced upon them, by the internal Use of solvent Medi* 

 cines, from Mr, William Brande to Everard Home, 

 Esq. F.R.S. 



Dear Sir, 



H. 



AVING availed myself of the opportunity you pro* Calculi in the 

 cured for me of making a chemical examination of the cal- Huntenan 

 culi contained in the Hunterian Museum, as well as those Mr. Homes 

 in your own collection, I herewith send you an account of 

 what I have done. 



Should the observations appear to you to throw any new 

 light upon the formation of calculi, I request, that you will 

 do me the honour of laying them before the Royal Society. 



The collection, which I have examined, is not only un- very numer- 

 commonly large, but the greater part of the specimens have ous > anc ! iu 6^ 

 histories of the case annexed to them. 



I> 2 This 



