< Page:Popular Science Monthly Volume 5.djvu
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THE POPULAR SCIENCE MONTHLY.

I would, however, ask Mr. Forbes to consider whether I, while endeavoring to hold the balance fairly between contending claims, should have been justified in accepting his father's assertion and ignoring the diametrically opposite assertion of Agassiz? On this point I would direct his attention to two sources of information; the one probably known to him, the other unknown, and which the desire not to inflame this controversy has prevented me from publishing hitherto.

In the first place, I will make a brief extract from a very rare brochure published by Agassiz, in evident affliction of mind, in 1842. In that pamphlet he addresses thus his guest of the previous autumn:

"What eloquence have I not wasted in order to cause you to accept such and such a conclusion; what lengthened excursions, extending over days, have I not made to convince you of such and such a fact? And what advantage did I derive from nearly a month of these labors? This solely. On every new subject of discussion you favored me with the profound reflections: it is very curious; it is very extraordinary; it is most remarkable; it is capable of various interpretations; various causes might have produced these effects! Never a word on the true basis of the question. And, notwithstanding this, I told you all, showed you all, even things regarding which I had published nothing."

I was in duty bound to give due weight to this side of the question; and in 1869, prior to the publication of the "Glaciers of the Alps," I wrote to M. Agassiz, inquiring whether he still maintained the position here assumed; which, it will be seen, not only touches, but is, the very point brought forward by Prof. George Forbes. I will give the pith of his reply, which, as just intimated, has lain beside me unpublished for fifteen years. After sketching the "incredible difficulties" of his early glacier campaigns, his uncertainty regarding the measurement of the motion of bowlders, his failure on the Aar, and Escher's failure on the Aletsch, to determine the motion of a series of stakes fixed in 1840, because, through ignorance of the amount of ablation, they did not sink them deep enough in the ice, Agassiz answers me thus:

"It was not until after my second visit to the Aar in the winter of 1840–'41 that I felt myself prepared for a systematic experimental investigation of the glacier; and I then went up, not with the hope of solving all the problems in one year, but with the view of laying the basis of a solution. The fact that I staked a series of poles across the whole width of the glacier, to a depth which left them standing to the following year, and that I then went up with an experienced engineer to make a minute map of the entire surface of the glacier, which was executed, will show that I had laid my plans for a successful survey of glacier phenomena before Prof. Forbes had, for the first time, set his foot upon the glaciers with a view to studying them.

"When I invited him to spend some time with me upon the glacier in 1841, I hoped to receive some valuable hints for my investigations from a physicist of so high a standing as his. But he never suggested any thing to me, while I showed him every thing I had been doing, explained all my difficulties, and the

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