PROCEEDINGS OF SOCIETIES. 245 



beautifully executed chromo-lithograpbs, whicli were handed round 

 for the inspection of the Fellows. (The paper is printed at p. 212.) 



The President felt quite siu-e that it would be the pleasure of all 

 who were present to return their thanks to M. Eenard for his 

 admirable paper ; and they would do so with the greater satisfaction, 

 seeing that it was not often they had the advantage of a paper from 

 a distinguished foreign gentleman. The subject was one of much 

 importance in geology ; indeed, there were few considerations of more 

 importance than the temperature at which these rocks were formed ; 

 and he thought they might well congratulate themselves upon having 

 brought before them the first paper which had been written upon the 

 subject of a new method of obtaining this temperature. He felt 

 personally much gratified to find that the results arrived at by 

 M. Eenard agreed so nearly with those which he had himself obtained 

 some time ago by a totally different process, his calculations being 

 based entirely upon the ratio of expansion of liquids, making the 

 cavities, in fact, act as self-registering thermometers. (Diagram 

 drawn on board.) When now examined, the cavities were found to be 

 only partially filled with fluid, and he had proceeded to find the 

 temperature necessary to expand the fluid sufficiently to make it fill 

 the cavity entirely. He thought it worth noting that M. Kenard's 

 temperatures may not be the actual temperatures at which the rocks 

 were formed, because he assumed that the liquid was in a state of 

 saturation ; but if this were not actually the case, then M. Eenard's 

 calculation may be really less than the true temperature, though it 

 was clear that whatever that might be, it could not be less than that 

 assigned by M. Renard. Considering the nature of the two methods 

 employed, that they were conducted upon entirely different bases, and 

 were independently arrived at, he thought the results were very 

 remarkable, M. Renard having found the temperature to be 307° C, 

 whilst he had himself placed it at 356° C, or a difference of only 49° C. 

 These figures seemed to show that those rocks had not been formed at 

 such a high temperature as some geologists had thought possible. 

 It was, in fact, not more than a dull red heat — a heat so dull as to 

 give out scarcely any light in the dark. He thought they must 

 certainly congratulate themselves upon having such a paper, and upon 

 having it brought before them for the first time. 



The cordial thanks of the Society were unanimously voted to 

 M. Renard for his paper. 



The Secretary called the attention of the Fellows to an improved 

 form of microscope and mounting lamp, designed by Mr. Sear and 

 manufactured by the Silber Light Company, which was placed on the 

 table for exhibition. It gave a very powerful light from a silber burner ; 

 and in addition to this advantage it had a heating table placed over 

 the lamp, on which slides might be warmed or dried as required. 



The Secretary said they had received a short paper from Professor 

 Rupert Jones — written by M. E. von Broeck — describing a new kind of 

 slip for mounting opaque objects. It was a contrivance for fastening on 

 the glass cover by means of tissue paper, in such a way that it might 

 easily be removed if it became necessary to get at the specimen, 



