Report of the Besearches of M. Agoifit. 830 



age of rocks. This comparison, however, explains nothing, 

 and there is not much analogy between a mass of rock and a 

 glacier. 



During the winter of 1841-2, these blue bands gave rise to 

 keen discussions ; and hence were an object of our marked at- 

 tention during our expedition of the summer 1842. In fact, 

 we were scarcely settled again at the Hotel des NeuchdteloiSy 

 when every one commenced to collect the whole of the facts, 

 for the purpose of explaining the phenomenon in the most sa- 

 tisfactory manner. Numerous observations have, in every re- 

 spect, confirmed M. Agassiz's first suppositions concerning the 

 origin of the blue bands, namely, that they are simply bands 

 of pure ice produced from water — an account which, at the 

 same time explains why these bands are especially numerous 

 near the moraine, where the glacier is subjected to the most 

 rapid thawing. We have not space here to produce all the 

 observations and experiments upon which this explanation is 

 grounded ; and, therefore, we refer our readers to the work 

 of M. Agassiz, which is in the press, wherein this question 

 will be fully considered, and accompanied with plans and 

 plates, which will facilitate its comprehension. I shall only 

 state, that to arrive at an accurate knowledge of their distri- 

 bution, M. Agassiz caused a trench to be cut a foot wide across 

 the whole breadth of the glacier, extending to 4000 feet, and 

 to a depth sufficient for the distinct examination of the bands, 

 even in those localities where the surface was most disin- 

 tegrated. 



This trench, opened at about a league from the Hotel de 

 NeuchdteloiSy was included in the transversal band of 500 feet, 

 of which we shall say more hereafter. It results from the 

 observations, made with the greatest care by M. Vogt, and 

 traced on a scale of one-tenth of the natural size, not only 

 that the bands are much more numerous and broader under 

 the moraines and in their neighbourhood, but also that there 

 are very marked differences between the right and the left 

 banks — differences which evidently result from the position 

 of the valley in relation to the sun. Upon the right bank, 

 which is protected from the solar rays by the Griinberg, the 

 bands are fewer and more distinctly circumscribed than on the 



