296 'Report of the Researches of M. Agassiz. 



observations we have made upon the great reservoirs. When 

 we arrived at the glacier of the Aar, at the beginning of July 

 1842, all the crevices, as well as the hollows of the older cas- 

 cades, were filled with water even to overflowing; after a few 

 days of fine weather, we readily perceived that the water had 

 sunk; and shortly afterwards it had so considerably diminished, 

 that it was quite impossible to attribute the fall of the surface 

 to the effect of evaporation alone. 



It would have been important to have ascertained how long 

 the water which is engulphed in the glacier near the Hotel 

 des Neuchatelois takes ere it is discharged at the terminal 

 vault. For the accomplishment of this desirable object, va- 

 rious experiments were proposed, some of which were in 

 principle mechanical, and others chemical ; that mechanical 

 method which appeared most simple, consisting in throwing 

 into a cascade some bodies, such as minute balls of wood, or 

 saw-dust, which would float with the stream. The saw-dust 

 from the oak appeared the most suitable, on account of its 

 specific gravity, which very nearly corresponds with that 

 of water; although there was much reason to fear that it 

 would but too readily adhere to the sides of the ice it encoun- 

 tered. The chemical method would have been preferable on 

 a small scale ; but it was very doubtful if any re-agent, how- 

 ever energetic, could detect the presence of a solution in such 

 an immense mass of water. Notwithstanding, we often tried 

 it. M. Agassiz desired two sacks of saw-dust to be transport- 

 ed from Meyringen to the glacier, which were there thrown 

 into a cascade or moulin^ at a certain hour in the morning ; 

 but we did not see the slightest trace of it at the extremity. 

 On another occasion, 30 quarts (litres) of the infusion of log- 

 wood were poured into the same cascade, without affbrding a 

 more satisfactory result. 



2. On the Blue BandSt or those of Infiltration. 

 Our attention, when continuously directed to the structure 

 of glaciers, could not but be attracted to many particulars 

 which are produced by the transformation to which the ice is 

 subjected in the progress of its course. Long ago we had 

 observed on the surface of the glaciers long rectilinear and 



