280 M. Renoir on the Glaciers of the Vosges, 



the minimum one so as to act with certainty ; this is not the 

 case, however, with the mercurial one, for it has heen found 

 that the glass enamel index used by Rutherford himself is 

 drawn back by the mercury, and the same happens witli 

 various substances. The material usually employed, and 

 which answers best, is steel ; this, however, is often rendered 

 useless by the mercury amalgamating with it. Various fluids 

 have been introduced to get the better of this, but all of these 

 are liable to the objection of mixing with the mercury. Af- 

 ter various unsatisfactory efforts, I at last found that, like the 

 story of Columbus and the ^^^^ it was the easiest thing in the 

 world, for it so happens, that, although mercury attracts glass 

 and amalgamates with steel, there is (for our purpose) no at- 

 traction between glass and steel, and mercury does not amal- 

 gamate with glass ; it is therefore only necessary to introduce 

 or interpose betwixt the mercury and steel a small piece of 

 glass, or second index, as is done in the thermometer on the 

 table. 



On the Glaciers which anciently covered the southern side of 

 the Mountain-chain of the Vosges, By M. Renoir. 



I have long remarked, at the foot of the ballon of Alsace, 

 on an arkose formation called the Tete-de-Flanches^ which 

 overlooks the town of Giromagny, a great number of trans- 

 ported blocks of stone, some of the accumulations of which have 

 a volume of 125 or 128 metres, and the height above the pre- 

 sent level of the valley amounts to 107 metres. 



I was accustomed to regard these blocks as having been 

 transported by some great currents ; this was the theory most 

 generally received ; but Captain Le Blanc, after having heard 

 the debates which took place respecting glaciers, at the meet- 

 ing of the Geological Society at Porrentruy, in September 

 1838, was the first, as far as I am aware, who considered the 

 blocks of Giromagny as possibly belonging to the ancient 

 moraine of a glacier. 



This view of them did not correspond to my notions, and 

 as M. Le Blanc had not at that period seen any moraines, his 



