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. [Sidenote: HALF OF SUMMER MOTION.] Line No. I.--Winter Motion in Twenty-four Hours. No. of stake. Inches. West 1 7-1/4 2 11 3 13-1/2 4 13 5 13-3/4 6 14-1/4 7 15-3/4 8 15-3/4 9 12-1/4 10 12 11 6-1/2 East. [Sidenote: THE SAME LAW IN SUMMER AND WINTER.] The maximum here is fifteen and three-quarters inches; the maximum summer motion of the same portion of the glacier is about thirty inches. These measurements also show that in winter, as well as in summer, the side of the glacier opposite to the Montanvert moves quicker than that adjacent to it. The stake which moved with the maximum velocity was beyond the moraine of La Noire. The second line crossed the glacier about 130 yards below the Montanvert. Line No. II.--Winter Motion in Twenty-four Hours. No. of stake. Inches. 1 7-3/4 2 9-1/2 3 13-3/4 4 16 5 16 6 15-3/4 7 17-1/2 8 16-1/2 9 14-1/2 10 14 The maximum here is an inch and three-quarters greater than that of line No. 1. The summer maximum at this portion of the glacier also exceeds that of the part intersected by line No. 1. The surface of the glacier between the two lines is in a state of tension which relieves itself by a system of transverse fissures, and thus permits of the quicker advance of the forward portion.