Repm't of the Researches of M. Agassiz. 299 



Professor Forbes, upon the invitation of M. Agassiz, joined us at 

 the commencement of the campaign, with the intention of study- 

 ing, along with us, the different phenomena in general physics 

 which the glaciers present. The parallel fissures often consti- 

 tuted, during the three weeks we together inhabited the Hotel 

 des Neuchdtelois, the subject of our communings and our dis- 

 cussions ; they appeared to us much more conspicuous than in 

 the former years, and when they were examined at the margin 

 of a crevice, it was distinctly seen that they corresponded to blue 

 bands of a very deep tint, which penetrated as far as the eye 

 could follow them into the crevices. They were seen equally 

 distinctly in the bed of all the streamlets which flowed near to 

 the Hotel des Neuchdtelois^ and, in general, in all submerged 

 places. The small space cleared of the rocky debris which 

 separates the two portions of the middle morain at the Hotel 

 des Neuchdtelois^ displayed it in abundance ; and the pheno- 

 menon was seen in perfection when we cleared away a part of 

 the moraine. We even remarked that it was under the mo- 

 raine, and in its immediate neighbourhood that the blue bands 

 were largest and most numerous, so much so that in certain 

 places the glacier appeared to be really composed of immense 

 plates of glass parallel to each other, and in juxtaposition. 

 Hence we never failed when any of our friends paid us a visit 

 to clear away a corner of the moraine to shew them the blue 

 bands, and many of them were so surprised that they imagined 

 it was a phenomenon which we had artificially produced. The 

 bands are of variable width, and their number in different 

 parts of the glacier varies no less. Some are ten inches or a 

 foot broad ; others scarcely a line. Upon the whole, the white 

 prevail greatly over the blue bands, although there are places 

 in which the latter occupy nearly as much space as the former. 

 When first exposed, the bands of blue ice are perfectly trans- 

 parent, and the eye can penetrate many feet deep. But this 

 transparency continues but for a very short time, and speedily 

 minute cracks are perceived, at first superficial, but soon they 

 form a net-work, and deprive the blue ice of all its transpa- 

 rency. These cracks also pervade the white bands ; and on 

 approximating the ear to the ice, we distinctly hear a slight 

 noise of crepitation produced at the moment of their forma- 



