[A] 'Edinb. Phil. Journ.,' Oct. 1846, p. 417.
[B] Agassiz, 'Système Glaciaire,' p. 522.
[C] On this latter occasion my guide volunteered to cut the steps for me up to the pickets; and I permitted him to do so. In fact, he was at least as anxious as myself to see the measurement carried out.
WINTER MOTION OF THE MER DE GLACE.
(12.)
The winter measurements were executed in the manner already described, on the 28th and 29th of December, 1859. The theodolite was placed on the mountain's side flanking the glacier, and a well-defined object was chosen at the opposite side of the valley, so that a straight line between this object and the theodolite was approximately perpendicular to the axis of the glacier. Fixing the telescope in the first instance with its cross hairs upon the object, its end was lowered until it struck the point upon the glacier at which a stake was to be fixed. Thanks to the intelligence of my assistants, after the fixing of the first stake they speedily took up the line at all other points, requiring very little correction to make their positions perfectly accurate. On the day following that on which the stakes were driven in, the theodolite was placed in the same position, and the distances to which the stakes had moved from their original positions were accurately determined. As already stated, the first line crossed the glacier about 80 yards above the Montanvert Hotel.
HALF OF SUMMER MOTION.
Line No. I.—Winter Motion in Twenty-four Hours.
| No. of stake. | Inches. | |
| West 1 | 71/4 | |
| 2 | 11 | |
| 3 | 131/2 | |
| 4 | 13 | |
| 5 | 133/4 | |
| 6 | 141/4 | |
| 7 | 153/4 | |
| 8 | 153/4 | |
| 9 | 121/4 | |
| 10 | 12 | |
| 11 | 61/2 East. |