162 Report of the Besearches of M. Agassiz. 



comes of this great mass of water 1 This is one of the great 

 problems of the study of glaciers, and on its solution depends 

 greatly the fate of the theory of infiltration. The first 

 observations on the lowering of the surface by melting, or, to 

 adopt the phrase of M. Agassiz, by the ablation of the surface, 

 were made in the year 1841, and published in Jameson's 

 Journal, vol. xxxiii. p. 275. When we revisited the glacier in 

 the month of July 1842, the position of our cylinders was 

 known by a small hillock of rubbish, like a gigantic mole- 

 hill, in the midst of which our No. 13 stood, indicating a 

 subsidence of about 4 feet. As the locality of this hole or 

 bore is rigorously determined, and easily discovered, all may 

 continue for the future to examine the amount of the ablation 

 of the surface in a given time. Supposing that this ablation 

 shall, on the average, amount to 10 feet a year, and that the 

 glacier continues to progress at the same rate, in other words, 

 at about the rate of 200 feet per annum, our cylinder No. 1 

 should arrive at the surface at the end of about fourteen years, 

 and that at a distance of about 3000 feet from its original in- 

 troduction. * 



Of three stakes introduced into the ice close to the same loca- 

 lity (see p. 155), two appeared at a height above the surface of 

 3 feet 7 inches, and the third at the height of S feet 5 inches- 

 The stakes placed transversely in the neighbourhood of M. 

 Hugi's hut, a quarter of a league farther down, were measured 

 somewhat later, on the 20th of July, and gave the following 

 indications. The stake No. 1 of the Finster-Aar indicated a 

 fall of 6 feet 5 inches ; the stake No. 2 of 5 feet 5 inches ; the 

 stake No. 3 of 4 feet 4 inches ; and the stake No. 1 of the 

 Lauter- Aar of 5 feet 2 inches. The other two stakes B and 

 C, of the Lauter- Aar, had lost their marks from friction. From 

 these data it results that the central part of the glacier, that 

 is to say, the portion which advances the most rapidly, was also 

 the part which had undergone the most considerable ablation. 



* In the paper by M. Agassiz quoted above, he speaks of 14 cylinders, and 

 mentions that the 14th was one foot and a half under the surface in Septembe 

 1841 (p. 276.) According to M. Desor, there were only 13 cylinders, and it was 

 the 13th which occupied the position just mentioned in 1841. In the same paper 

 (pp. 276 and 277) M. Agassiz supposes 5 feet for the amount of annual ablation, 

 and therefore calculates that 28 years must be required for the cylinder No. 1 

 reaching the surface, instead of 1 4 as now estimated by M. Desor. We mention 

 tliis merely to assist our readers in their references. — Edit. 



