Prof. Maskelyne and Dr. Lang's Mineralogical Notes. 39 



other side; that, in point of fact, the anterior side is the colder, 

 and the other the hotter V 



Such is the theory that I gave. It is the same as Mr. Tom- 

 linson's. The only difference between ns is this, — that the con- 

 clusion I came to more than twenty years ago he has arrived at 

 and considers to be new today. 



Of the correctness of that explanation I have never since had 

 any doubt. To show how well it was understood at that time, I 

 may add that the Editor of the Philosophical Magazine himself, 

 in a foot-note to the communication in the Number of the Journal 

 I have just quoted, made a suggestion for the purpose of remo- 

 ving one of the difficulties which was in its way. 



Yours truly, 



University, New York, JOHN W. DRAPER. 



November 28, 1862. 



VI. Mineralogical Notes. By Professor Maskelyne and 



Dr. Viktor von Lang, of the British Museum*. 



[With Three Plates.] 



1. On Connellite. By Nevil Story Maskelyne. 



THE rare mineral Connellite has never had a satisfactory 

 locality assigned to it. To an old specimen in the British 

 Museum a label was attached which gave'Chessy as its locality; 

 but the aspect of the specimen, and the minerals it consisted of, 

 were not those by which the mineralogist recognizes the products 

 of that famous French working. All the few known specimens, 

 on the contrary, bear their united testimony to a Cornish source 

 of this beautiful mineral, from the manner in which a massive 

 and sometimes crystalline cuprite intervening quartz, carries 

 chrysocolla and often also cupreous arseniates as a coating, or in 

 small deposits in its hollows and fissures. My attention had 

 been attracted to the mineral by the observation that the minute 

 blue velvet-like filaments which compose it seemed to possess 

 resplendent planes. Placing some under the microscope, they 

 proved to be distinct and beautiful crystals. 



During last autumn, Mr. J. M. Williams showed me his 

 splendid collection in Cornwall. I searched in it for specimens 

 of Connellite, and succeeded in finding two or three drawers, 

 through which were scattered a few specimens of this most rare 

 and beautiful mineral. They were mingled with specimens of 

 Xiroconite andCopper-mica; and the drawers which had contained 

 them previously to their removal to Carhays Castle were stated 



* Communicated by the Authors. 



