East West Stake 1 2 3 4 5 6 7 8 9 10 11 Inches 20 23 29 30 34 28 25 25 25 18 9 172. Both the first stake and the eleventh in this series stood near the sides of the glacier. On the eastern side the motion is 20 inches, while on the western side it is only 9. It rises on the eastern side from 20 to 34 inches at the 5th stake, which we, standing upon the glacier, can see to be much nearer to the eastern than to the western side. _The united evidence of these three lines places the fact beyond doubt, that opposite the Montanvert, and for some distance above it and below it, the whole eastern side of the glacier is moving more quickly than the western side._ § 24. _Suggestion of a new Likeness of Glacier Motion to River Motion. Conjecture tested._ 173. Here we have cause for reflection, and facts are comparatively worthless if they do not provoke this exercise of the mind. It is because facts of nature are not isolated but connected, that science, to follow them, must also form a connected whole. The mind of the natural philosopher must, as it were, be a web of _thought_ corresponding in all its fibres with the web of _fact_ in nature. 174. Let us, then, ascend to a point which commands a good view of this portion of the Mer de Glace. The ice-river we see is not straight but curved, and its curvature is _from_ the Montanvert; that is to say, its convex side is east, and its concave side is west (look to the sketch). You have already pondered the fact that a glacier, _in some respects_, moves like a river. How would a river move through a curved channel? This is known. Were the ice of the Mer de Glace displaced by water, the point of swiftest motion at the Montanvert would not be the centre, but a point east of the centre. Can it be then that this "water-rock," as ice is sometimes called, acts in this respect also like water? 175. This is a thought suggested on the spot; it may or it may not be true, but the means of testing it are at hand. Looking up the glacier, we see that at _les Ponts_ it also bends, but that there its convex curvature is towards the western side of the valley (look again to the sketch). If our surmise be true, the point of swiftest motion opposite _les Ponts_ ought to lie west of the axis of the glacier. 176. Let us test this conjecture. On July 25 we fix in a line across this portion of the glacier seventeen stakes; every one of them has remained firm, and on the 26th we find the motion for 24 hours to be as follows:-- Fourth Line: D D' upon the Sketch. East West Stake 1 2 3 4 5 8 7 8 9 10 11 12 13 14 15 Inches 7 8 13 15 16 19 20 21 21 23 23 21 22 17 15