165. You have already assured yourself by actual contact that the body of the glacier is real ice, and you may have read that glaciers move; but the actual observation of the motion of a body apparently so rigid is strangely interesting. And not only does the ice move bodily, but one part of it moves past another; the rate of motion augmenting gradually from 12 inches a day at the side to 33 inches a day at a distance from the side. This quicker movement of the central ice of glaciers had been already observed by Agassiz and Forbes; we verify their results, and now proceed to something new. Crossing the Glacier du Géant, which occupies more than half the valley, we find that our line of stakes is not yet at an end. The 10th stake stands on the part of the ice which comes from the Talèfre. [Illustration: OUTLINE PLAN, SHOWING THE MEASURED LINES OF THE MER DE GLACE AND ITS TRIBUTARIES.] 166. Now the motion of the sides is slow, because of the friction of the ice against its boundaries; but then one would think that midway between the boundaries, where the friction of the sides is least, the motion ought to be greatest. This is clearly not the case; for though the 10th stake is nearer than the 9th to the eastern or _Chapeau_ side of the valley, the 10th stake surpasses the 9th by 6 inches a day. 167. Here we have something to think of; but before a natural philosopher can think with comfort he must be perfectly sure of his facts. The foregoing line ran across the glacier a little below the Montanvert. We will run another line across a little way above the hotel. On July 18 we set out this line, and to multiply our chances of discovery we place along it 31 stakes. On the subsequent day five of these were found unfit for use; but here are the distances passed over by the remaining six-and-twenty in 24 hours. Second Line: B B' upon the Sketch. West Stake 2 3 4 5 6 7 8 9 10 11 12 13 Inches 11 12 15 15 16 17 18 19 20 20 21 21 Stake 15 16 17 18 19 20 21 22 23 24 25 26 Inches 23 23 23 21 23 21 25 22 22 23 25 26 East