204 THE LIFE OF JAMES 1). FORBES. [CHAP. 



Journal, August 



' A charming walk from Guttannen to the Grimsel. 

 We carefully examined the polished rocks as we passed, 

 rising as they do 1,500 or 2,000 feet above the valley. 

 They are not all polished, and even for large spaces 

 there is not a trace, but I observed two facts which 

 I think nearly general. (1) The polish is decidedly 

 greatest on the side of every projecting rock looking 

 up the valley, against which, therefore, the ice would 

 abut. (2) The inclination of the striae does not de- 

 pend, as Agassiz supposes, on the combination of the 

 vertical motion of the block in the ice with the longi- 

 tudinal motion of the ice (which would be an insen- 

 sible quantity), but the striae rise before a contraction 

 of the valley, and fall after such a contraction : the ice 

 rises to surmount an obstacle ; having surmounted it, 

 it falls. . . . 



' I cannot for one moment doubt that the configu- 

 ration of the rocks in the valley of Hasli is entirely 

 superficial, and independent of crystalline or other 

 structure, and that it is not performed by water. The 

 continuity of the strokes, the depth of the furrows 

 relatively to the hardness of the rocks, the immense 

 height above the valley to which this polishing action 

 extends, seem conclusively to negative the idea of water 

 action. . . / 



In the afternoon Agassiz went back to the Aar 

 Gletscher, while Forbes and Mr. Heath ascended the 

 Sidelhorn, finding, on their return, that Mr. Faraday 

 had arrived at the Grimsel. The next day again saw 

 them inmates of the hut. 



' In the evening we had a splendid display of the 

 phenomenon of the shadow of mountains projected on 

 clouds, which I once saw by moonlight at the Mer de 

 Glace at Chamouni. It was about 6 o'clock, when the 

 sun was near setting. The peaks of the Lauter-Aar and 

 Hugi-horner were grandly depicted on a cloud a short 

 way above them. This evening there slept at the 



