In Switzerland he spent his summer holidays both in 1856 and 1857, in the latter year examining the glaciers with Tyndall scientifically, as well as seeking pleasure by the ascent of Mont Blanc. As fruits of this excursion were published late in the same year, his "Letter to Mr. Tyndall on the Structure of Glacier Ice" ("Phil. Mag." 14 1857), and the paper in the "Philosophical Transactions of the Royal Society," which appeared--much against his will--in the joint names of himself and Tyndall. Of these he wrote in 1893 in answer to an inquiry on the subject:--] By the Observations on Glaciers I imagine you refer to a short paper published in "Phil. Mag." that embodied results of a little bit of work of my own. The Glacier paper in the "Phil. Trans." is essentially and in all respects Professor Tyndall's. He took up glacier work in consequence of a conversation at my table, and we went out to Switzerland together, and of course talked over the matter a good deal. However, except for my friend's insistence, I should not have allowed my name to appear as joint author, and I doubt whether I ought to have yielded. But he is a masterful man and over-generous. [And in a letter to Hooker he writes:--] By the way, you really must not associate me with Tyndall and talk about OUR theory. My sole merit in the matter (and for that I do take some credit) is to have set him at work at it, for the only suggestion I made, namely that the veined structure was analogous to his artificial cleavage phenomena, has turned out to be quite wrong. Tyndall fairly MADE me put my name to that paper, and would have had it first if I would have let him, but if people go on ascribing to me any share in his admirable work I shall have to make a public protest. All I am content to share is the row, if there is to be one. [The following letters to Hooker and Tyndall touch upon his Swiss trips of 1856 and 1857:--] Berne, September 3, 1856. I send you a line hence, having forgotten to write from Interlaken, whence we departed this morning.