506 PROCEEDINGS OF THE ACADEMY OF [1899. 



afiording au excellent view of the surface of the ice, we deter- 

 mined to use its ridge as the station for the transit. Observations 

 had been made to determine the mean direction of flow of the ice, 

 and on the 31st of July, 1899, the transit was adjusted on the 

 ridge. A large tree Avas taken as a line mark on the left side of 

 the valley. 



The plan of measuring a distance of 250 feet between the plates 

 by means of a tape measure was proved to be impracticable on 

 going on the ice. While the surface was comparatively smooth, it 

 was rolling and broken by valleys running at right angles to the 

 direction in which the measurements were to be made. In nearly 

 every case it was not possible to see from one plate to the next. 

 We accordingly decided to abandon the actual measurement, and 

 after adjusting the plates, to lay out a base line and take the 

 angles to the plates from each end. The results could then be 

 plotted on the map and the distances obtained. This plan worked 

 well, and on the second visit we were able to place a transit at 

 each end of the base line, and make readings of both angles at 

 the same time. 



Eight steel plates were laid out on the line shown on the map. 

 At this point the total breadth of the glacier is 1720 feet. Owing 

 to the rounded surface of the glacier the position for the ninth 

 plate was not visible from the ends of the base line, and as it was 

 quite close to the left border it was omitted altogether. 



On the 11th of August, or eleven days later, transits were set 

 up at each end of the base line and the bearings to each of the 

 plates taken. At the same time the exact movement of the plates 

 was accurately measured from the direct line in which they had 

 originally been placed. This will be found noted in the fourtli 

 column of the table. 



