64 Proceedings of Philosophical Societies. [July, 



with a view to more delicate and refined results, professional 

 engagements have since prevented their being completed. The 

 further prosecution of these labours will be conveyed through the 

 medium of this Journal, at a period not far distant. 



Article XIII. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



On Thursday, May the 27th, a paper by Mr. Cater was read, 

 comparing the Cassegrenian and Gregorian telescopes. These 

 telescopes have been hitherto considered as quite similar. Mr. 

 Cater was led to compare them in consequence of telescopes of 

 both kinds being constructed by a self-taught artist at Ipswich, 

 who has acquired the art of constructing both in remarkable 

 perfection. The result of the comparison was, that the Casse- 

 grenian telescope gave a much clearer and better defined image 

 of the object than the Gregorian. Mr. Cater endeavours to 

 account for this difference, by supposing that in the Gregorian 

 telescope the particles of light interfere, and impede one another; 

 while this does not happen in the Cassegrenian. 



On Thursday, June the 3d, part of a paper by Mr. Brande 

 was read, containing additional facts and observations on the 

 use of magnesia in cases of urinary calculus. The paper was 

 divided into two sections. In the first, Mr. Brande related 

 several cases in which the deposition of uric acid in urine and 

 the accompanying symptoms were removed by the use of mag- 

 nesia. Among others, a Gentleman of fifty-five was afflicted 

 with pain in the kidney ; a calculus at last passed into the 

 bladder, and was voided by the urethra; it consisted of uric 

 acid. His urine deposited a considerable quantity of red sand 

 (uric acid). He tried alkalies; but they disagreed with his 

 stomach. He was induced, in order to alleviate the symptoms 

 of indigestion, to take a tea-spoonful of magnesia daily. His 

 symptoms were gradually removed, and the urine ceased to de- 

 posite red sand. Several similar cases were given, in all of which 

 the deposit of uric acid was put an end to by the use of magnesia. 

 But in one case, after a certain time, the symptoms were aggra- 

 vated, and a white sediment was deposited. This turned out, on 

 examination, to be a mixture of phosphate of lime and phosphate 

 of magnesia-and-ammonia. The object of the second section 

 of the paper was to give an account of the treatment in such 

 cases. Acids were administered, and different kinds were tried. 

 Carbonic acid In the form of soda water, citric acid, vinegar, 

 <pider, oranges, lemonade, and muriatic acid, were tried in sue- 



