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THE POPULAR SCIENCE MONTHLY, 



I would, however, ask Mr. Forbes to consider whether I, while en- 

 deavoring 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 

 vs'ord 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 1859, 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 ^5, 

 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 unpublished for fifteen years.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 difli- 

 culties" of his early glacier campaigns, his uncertainty regarding the 

 measurement of the motion of bowlders, his failure on the Aai', 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 w^ith an ex- 

 perienced 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 



