REXDU AND HIS EDITORS. 455 



not the very strongest point, is the following. Speaking of the prin- 

 ciple of plasticity, Prof. Forbes writes : 



" Perhaps the following illustration will appear to the impartial reader al- 

 most a demonstration of this principle. . . . There is a glacier basin in the 

 range of Mont Blanc called the Glacier du Talefre. Its outline is correctly rep- 

 resented in the next figure, as well as the relative dimensions of the mouth or 

 outlet bj which it pours forth the mass of ice which it is annually unable to 

 contain in its circuit. The breadth of the outlet is about seven hundred yards, 

 while the greater diameter of the basin which it discharges is more than forty -two 

 hundred yards, or at least six times greater. Can it for one moment be ima- 

 gined that any degree of liibricatmi of the bed of this cake of ice could drag it 

 through the strait in question, even if its adhesion to the soil were absolutely 

 nothing? The thing is impossible ; it speaks for itself." ^ 



The observation here referred to as so convincing is precisely of 

 that class upon which Rendu founded his theory ; and there cannot 

 be a reasonable, doubt that the very fact here brought forward more 

 or less influenced him. Still, while in the hands of Prof. Forbes it has 

 the value here set forth, in those of Rendu the " ingenious specula- 

 tions " founded upon it are not "worthy of confidence." 



It is not, and never was, my design to charge Principal Forbes 

 with conscious wrong ; but, at the time here referred to, I believed 

 him to be animated by a love of public recognition so eager, and an 

 estimate of the value of his own work so exalted, as to render it diffi- 

 cult for him to behave in a generous way toward those whose labors 

 trenched upon his own. I regarded his treatment of Agassiz as 

 harsh, if not merciless. Considering all this, I do not think that the 

 " Glaciers of the Alps," written in the midst of such contentions as I 

 have indicated, can be justly deemed intemperate in tone. Its logic 

 is sometimes stern ; ^ but its statements are irrefutable. To its chap- 

 ters, from page 269 onward, I would refer the reader for an answer to 

 a good deal of the irrelevant bluster associated with this question. 



1 am blamed for saying that, if Rendu had added to his other 

 qualifications those of a land-surveyor, he would now be deemed the 

 "Prince of Glacialists." Can this be for a moment doubted ? When 

 we find him announcing, with a fullness and precision never sur- 

 passed, and not attained even by Prof. Forbes himself until years 

 after the publication of his " Travels," the character of glacier-mo- 

 tion ; when we find him laboriously trying to determine it by obser- 

 vations of blocks at the edge and toward the middle of the glacier — 

 is it tobe imagined that, if he knew the use of the theodolite, he would 

 not have employed that instrument ? And is the absence of this sur- 

 veyor's knowledge a just reason for dismissing his labors in the fol- 



^ Philosophical Magazine, vol. xxvi., pp. 414, 415. 



2 What a courteous demeanor might have done to modify this, I cannot now say, but 

 I l?now that, after the death of Principal Forbes, no reference of mine to his work or 

 memory lacked appreciation or kindness. 



