330 THE LIFE OF JAMES D. FOUBES. [CHAP. 



appears to be a good circle, carrying a powerful telescope, 

 which is permanently fixed within the window of the 

 pavilion, and is adjusted upon a mark on the other side 

 of the glacier. . . . Besides the mark on the medial 

 moraine (700 metres distant from the pavilion) are two 

 others, one on each glacier. 



* Close under the promontory of Trift, below the prin- 

 cipal crevasses, and where the glacier, having subsided 

 considerably in level, has settled against the rock which 

 it closely embraces, is the apparatus for registering the 

 motion near the edge of the glacier. This is extremely 

 simple, consisting of a board fixed to the rock, while at 

 right angles to this, and nearly touching it, a horizontal 

 lath is fixed to two supports planted on the glacier : and 

 this lath is of course slowly carried along the board by 

 the motion of the ice to which it is attached. This 

 apparatus is used for observing not only the forward 

 motion, but also any approach to or recession from the 

 rock by the ice, as well as any change of level. The 

 latter takes place continually, and with tolerable regu- 

 larity in an upward direction, as I could judge from the 

 series of pencil marks registering advance and ascent 

 made from time to time during the last fortnight by M. 

 Dolfuss-Ausset. This ascent appears paradoxical from 

 the situation, the glacier being at that spot in the act of 

 subsiding into a hollow : but I imagine it may be ex- 

 plained by an outward and upward pressure exerted by 

 the main current of the glacier on the ice which fills a 

 sort of bay on the lee side of the promontory of Trift. This 

 ice, which is exceedingly smooth and plane, would thus 

 be squeezed outwards and upwards against the rock, with 

 but little forward motion. 



* The apparatus and mode of observation were kindly 

 shown me by M. Dolfuss when I visited the pavilion on 

 my return from the Abschwung. 



* On the whole, I was greatly struck with the uncre- 

 vassed condition of the glacier in its central part. The 

 glacier of the Grunberg is decidedly concave, while those 

 of the Lauter and Finster Aar are very convex near the 



