184 TWELFTH LETTER ON GLACIEKS. [1846 



to an object on the farther side of the glacier, two vertical holes 

 were made at (1) and (2), the first on the nearer, the second on the 

 farther side of the remarkable veined structure already described. 

 If that structure was occasioned, as I suspected, by the rapidity 

 with which the farther portion of the ice was moved past the 

 nearer portion, such difference of velocity might be expected to 

 be observed in a marked manner. The mark (1) was about 50 

 feet from the nearest edge of the glacier, and 103 feet below 

 the station B. The mark (2) was about 170 feet farther and 

 60 feet higher. An approximate section of this part of the 

 glacier, together with the measurements on which it is founded, 

 is given in Plate VIII. fig. 4, and will serve to compare the state 

 of matters at any future time. The following table gives the 

 result of the motions for two days : 



Motion. Motion for 24 hours. 



No. (1.) No. (2.) No. (1.) No. (2.) 



1846. Hour. inch. inch. inch. inch. 



Augusts, 9iA. M . 5 . 7 15 . 7fi 



9, 



3-7 11-25 4-55 13-85 



Sums, 9-4 27-0 Means, 4-90 14'2 



consequently the velocity of motion had increased in the space 

 of 170 feet traversed by the veined structure, in the ratio of no 

 less than 29 to 10. 



I also examined the condition of motion of the embayed 

 ice in the position C on the ground-plan, of which a section 

 (on a scale much larger than the last) is given in fig. 3. It 

 is made through the visual line, or in the direction C, C 2 of the 

 plan [p. 182]. Two pins were fixed at C 1 by excavating a niche 

 in the nearly vertical face of the ice ; one was placed vertically, 

 the other horizontally. At C 2, 40 feet higher and 69 feet more 

 distant, a vertical pin was placed. The diagonal from C to C 1 

 was also accurately measured with a line. After more than 24 

 hours' interval, it was found that the two marks at C 1 had not 

 moved towards the right hand, or in the direction of motion of 

 the glacier by the smallest perceptible quantity and that [the] 



