124 MINERALOGY OF CHALANCHES. 



~: T~7T — m ~7"/~^ — .~TT J which, when b vanishes, 



becomes 77? y* -, as in Lagvange^s theorem, and, when 6 is 



small, m{ >J - A . 1, or m * ; but if <*- 



\ V 2 ^4 V (2a + b))' a/ (2«)' 



were small, it would approach to ?w \/ &, the velocity due to 



the whole height of the wave. 



V. 



■A Mineralogical Descripti$n of the Mountain and Silver 

 Mine of Chalanches, in the Department of the Istre^ By 

 IIericailt be Thury, Mine Engineer*, 



Mountain of JL HE mountain of Chalanches, noted in the annals of mi- 



Chalanclies. ne ralogy for the variety and beauty of the mineral sub- 

 stances met with in it, is now become celebrated in metal- 

 lurgy, for the abundance and richness of its silver ores. 



Situation, and This mountain is in the vicinity of Allemont, in thp can? 



height. ton f pQisansf. It is above the confluence of the Olle 



and the Ilomanche, 2 myriam. [about 12 miles] east of 

 Grenoble in a straight line. Its height, taken at the build- 

 ings belonging to the silver mines, is 2159 niet. [2359 yards] 

 above the level of the sea ; but some primitive peaks, 

 stretching from south-east to north-west, rise 580 or 590 

 met. [635 or 645 yards] higher. Its loftiest summit is about 

 2750 met. [3005 yards]. 



Noticed by se- Many celebrated mineralogists have written on this moun- 



Teral, but im- ^j^ Schreiber, director of the practical school of Montr 

 perfuctlv. ' 



Blanc, who superintended the working of the silver mines 



at Chalanches several years with great success, has published 



hi si 



* Abridged from the Journal des Mines, vol. XX, p. 41. 



•Y The canton of POisans is the richest country in Fiance with respect 

 to its mineral substances. Its lofty mountains conceal ;i great number of 

 vein;, the various and superb products of which are daily eiiricliiug out 

 1 collections. 6 St< 



many 



