National Geographic : 1892 Mar 21
The Rate of Ice-flow. 45 In addition to the flags, five stakes were planted in a line and about equal distances apart on the eastern side of the glacier, as shown in the map. Their movement was determined from August 6 to 29. The table gives the total movement during that time at right angles to the line of the flags, which was the direction of the slope. The direction of the moraine shows that this is approximately the direction of motion. Movement of Stakes. a 0 b 7 inches. c 11 d 3.5 e 0 This amounts to about 2" a day for the middle flag. Conditions holding at the Ends of Glaciers. Alpine Glaciers.-It has been long recognized that the com paratively stationary position of the end of a glacier is due to the FIGURE 1-End of an Alpine Glacier. general equality between the quantity of -ice flowing down and the quantity melted. The mean temperature of a valley increases as we descend; if, therefore, the end ofthe glacier should advance beyond the point where the rate of melting equals the rate of supply, the ice would melt more rapidly and the end would recede. If, on the other hand, the glacier should not reach this point, ice would flow down faster than it would melt, and the end of the glacier would advance. This point is not merely a point of equilibrium, but a point of stable equilibrium. This explanation is sufficient, so long as we merely look upon the end of a glacier as a whole. But when we consider each part of the end by itself we are met by difficulties which do not seem so far to have been noticed.
1892 May 15
1892 Feb 19