1846.] MOTION OF GLACIER OF NANT BLANC, 197 



and position will be understood from a reference to the general 

 Map of the Mer de Glace. It is shaped somewhat like a tongue, 

 and is steep, without being much crevassed or very uneven, at 

 least in its middle region, where it is about 1000 feet broad, 

 where cattle are every year compelled to traverse it ; yet even 

 there it has an inclination of 18 or 20 near its centre. This 

 glacier terminates at a considerable height above the Mer de 

 Glace, and gives rise to the Nant Blanc, a torrent which gives 

 its name to the glacier, and whose volume and appearance is 

 subject to remarkable changes, depending upon the state of the 

 weather. It [the glacier] is supported on a vast pile of blocks 

 which it has brought down, and which forms its moraine ; and 

 whilst on the left bank the ice overhangs the moraine, on the 

 right, the latter being elevated in a mound, forms a barrier to 

 the former.* This glacier has a very small and crevassed nev, 

 taking its origin amongst the rugged rocks between the Aiguilles 

 of Dru and Bochard. The veined structure of the ice of the 

 glacier is perfectly normal, exhibiting the parabolic loops with 

 the frontal dip inwards. Its general form resembles that of the 

 Glacier des Bossons. 



I stationed my theodolite on the northern moraine, and 

 fixed a station towards the centre of the glacier, or rather on 

 the axis of the structural bands, which usually intimates the 

 point of swiftest motion. The inclination of the glacier was 

 here, as already mentioned, 18 or 20. Notwithstanding this 

 great declivity, the mean motion from August 4 to August 15, 

 was only 9*9 inches daily. 



Glacier du Miage. In order to complete here the observa- 

 tions on the velocity of motion of different glaciers, I shall 

 include those made also on the south side of Mont Blanc. I 

 had intended to have made a considerable number of experi- 

 ments on the remarkable Glacier du Miage, fully described in 

 my Travels, Chap. X., but I found it less suitable than I ex- 

 pected. I renewed, however, my survey of all the middle 

 region of the glacier ; and I ascertained the motion of its 



* [See Plate VIII. fig. 6.] 



