those acquainted only with such dangers as I then experienced the account which I have just given must appear exaggerated. I can only say that the track which I pursued in 1858 bore no resemblance in point of difficulty to that which I followed in 1857. The reason probably is, that in my first expedition neither myself nor my companion knew anything of the route, and we were totally destitute of the adjuncts which guides commonly use in crossing the Grand Col.'

I.

OBSERVATIONS ON THE MER DE GLACE.

THE law established by Forbes and Agassiz, that the central portions of a glacier moved faster than the sides, was amply illustrated and confirmed by the deportment of lines of stakes placed across the Mer de Glace and its tributaries in 1857. The portions of the trunk glacier derived from these tributaries were easily traceable throughout the glacier by means of the moraines. Thus, for example, the portion of the trunk stream derived from the Glacier du Géant might be distinguished in a moment from the other portions by the absence of débris upon its surface. Attention was drawn by Prof. Forbes to the fact that the eastern side of the Mer de Glace in particular is excessively crevassed;' and he accounted for this crevassing by supposing that the Glacier du Géant moves most swiftly, and in its effort to drag its more sluggish companions along with it tears them asunder, thus producing the fissures and dislocation for which the eastern side of the glacier is remarkable. Too much weight must not be attached to this explanation.

6

It was one of those suggestions which are perpetually thrown out by men of science during the course of an investigation, and the fulfilment or non-fulfilment of which cannot materially affect the merits of the investigator. Indeed, the merits of Forbes must be judged on far broader grounds. The qualities of mind and the physical culture invested in his Travels in the Alps' are such as to make it, in the estimation of the physical investigator at least, outweigh all other books upon the subject.

While thus acknowledging its merits, however, let a free and frank comparison of its statements with facts be instituted. To test whether the Glacier du Géant moved more quickly than its fellows, five different lines were set out across the Mer de Glace, in the vicinity of the Montanvert. In each case it was found that the point of swiftest motion did not lie upon the Glacier du Géant at all, but was displaced so as to bring it comparatively close to the eastern side of the glacier. But though the special opinion of Forbes just referred to here falls to the ground, the deviation of the point of swiftest motion from the centre of the glacier will probably, when its cause is pointed out, be regarded as of special importance to his theory.

At the place where these five lines were run across it the glacier turns its convex curvature to