I took with me in 1864 a theodolite to Pontresina, and while there had to congratulate myself on the aid of my friend Mr. Hirst, who in 1857 did such good service upon the Mer de Glace and its tributaries. We set out three lines across the Morteratsch glacier, one of which crossed the ice-stream near the well-known hut of the painter Georgei, while the two others were staked out, the one above the hut and the other below it. Calling the highest line A, the line which crossed the glacier at the hut B, and the lowest line C, the following are the mean hourly motions of the three lines, deduced from observations which extended over several days. On each line eleven stakes were fixed, which are designated by the figures 1, 2, 3, &c. in the Tables. Morteratsch Glacier, Line A. No. of Stake. Hourly Motion. 1 0.35 inch. 2 0.49 inch. 3 0.53 inch. 4 0.54 inch. 5 0.56 inch. 6 0.54 inch. 7 0.52 inch. 8 0.49 inch. 9 0.40 inch. 10 0.29 inch. 11 0.20 inch. As in all other measurements of this kind, the retarding influence of the sides of the glacier is manifest: the centre moves with the greatest velocity. Morteratsch Glacier, Line B. No. of Stake. Hourly Motion. 1 0.05 inch. 2 0.14 inch. 3 0.24 inch. 4 0.32 inch. 5 0-41 inch. 6 0.44 inch. 7 0.44 inch. 8 0.45 inch. 9 0.43 inch. 10 0.44 inch. 11 0.44 inch. The first stake of this line was quite close to the edge of the glacier, and the ice was thin at the place, hence its slow motion. Crevasses prevented us from carrying the line sufficiently far across to render the retardation of the further side of the glacier fully evident. Morteratsch Glacier, Line C. No. of Stake Hourly Motion. 1 0.05 inch. 2 0.09 inch. 3 0.18 inch. 4 0.20 inch. 5 0.25 inch. 6 0.27 inch. 7 0.27 inch. 8 0.30 inch. 9 0.21 inch. 10 0.20 inch. 11 0.16 inch. Comparing the three lines together, it will be observed that the velocity diminishes as we descend the glacier. In 100 hours the maximum motion of three lines respectively is as follows: Maximum Motion in 100 hours. Line A 56 inches Line B 45 inches. Line C 30 inches.