the Motion of Glaciers, 211 



Let us first consider the motion of scale I. (distant about 

 35 metres from the margin of the glacier). During the after- 

 noon the point moves but little, horizontally as well as verti- 

 cally, and that in the positive direction. In the later hours 

 p.m. this motion constantly diminishes, and at last entirely 

 ceases. After this, during the night (6 h -18 h ), the point moved 

 vertically upwards, and horizontally towards the valley. As 

 soon as the sun's irradiation commences (about 19 h ), absolutely 

 irregular motions take place, which last till noon ; then (from 

 h onward) again commence the slow downward movements, 

 and all is repeated in like manner. 



With Scale II. (more towards the middle of the glacier) the 

 course of the movements is similar. During the afternoon a 

 tolerably uniform motion takes place both horizontally and ver- 

 tically, in the positive direction ; at about 4 h the glacier comes 

 to a stand. But in the night, in the horizontal direction a con- 

 siderable retrograde movement came in (the opposite of what 

 took place with Scale I.), possibly amounting to 9*9 centims., 

 while the vertical motion almost always remained but feeble. 

 Then, as in the case of Scale I., with the commencement of the 

 solar irradiation begin the irregular movements, which last on 

 till midday, and thereupon pass over again into the regular 

 downward motion. 



Even at a point situated about 1 kilometre further up the 

 glacier similar movements of the ice were ascertained. Briefly^ 

 at all points observed by us the maximum of the variations of 

 the motions falls in the forenoon, commencing with the irra- 

 diation of the glacier by the sun. Thus, everywhere (at least 

 on the west side of the glacier) the sum of the motions during 

 the night was a going back toward the mountain. 



The observations of the 4th of September, finally, show that 

 with a less intense irradiation the motions of the glacier become 

 correspondingly less considerable. The motion of the glacier 

 was similar on the other days of observation. 



From the observations which have at present been made it 

 is not yet possible to perceive which of the more or less pro- 

 bable hypotheses would explain the actual motion of the ice. 

 We intend to continue these labours on a larger scale at the 

 commencement of the coming summer. 



Freiburg im Breisgau, Sept. 17, 1879, 



