7S o THE POPULAR SCIENCE MONTHLY. 



the Mer de Glace moves past the edges in a very considerable pro- 

 portion, quite contrary to the opinion generally entertained." This 

 communication, as I have said, bears the date of July 4th ; but it was 

 first published in the October number of the journal to which it was 

 addressed. My reason, therefore, for mentioning Agassiz first in the 

 " Forms of Water " is, that, apart from all personal complications, 

 his experiment was begun ten months prior to that of his rival, and 

 that he had also two months' priority of publication. 



Neither in his " Travels in the Alps," nor in his " Occasional Pa- 

 pers," does Principal Forbes, to my knowledge, make any reference 

 to this communication of Agassiz. I am far from charging him with 

 conscious wrong, or doubting that he justified this reticence to his 

 own mind. But my duty at present lies with objective facts, and not 

 with subjective judgments. And the fact is that, for eighteen years 

 subsequent to this campaign of 1842, Agassiz, as far as the glaciers 

 are concerned, was practically extinguished in England. The labors 

 of the following years failed to gain for him any recognition. His 

 early mistake regarding the quicker motion of the sides of a glacier, 

 and other weaknesses, were duly kept in view ; but his positive meas- 

 urements, and his Atlas, which prove the observations upon the glacier 

 of the Aar to be far more complete than those made upon any other 

 glacier, were never permitted to yield the slightest credit to their au- 

 thor. I am no partisan of Agassiz, but I desire to be just. 



Here, then, my case ends as regards the first reference to Principal 

 Forbes, in section 20 of the " Forms of Water." 



In section 48 I describe the dirt-bands of the Mer de Glace, and 

 ascribe the discovery of them to Principal Forbes. There can be no 

 thought of a " charge " here. 



The next reference that has any bearing upon this discussion oc- 

 curs in sections 59 and 60 of the " Forms of Water." I quote it fully: 



"By none of these writers is the property of viscosity or plasticity ascribed 

 to glacier-ice ; the appearances of many glaciers are, however, so suggestive of 

 this idea that we may be sure it would have found more frequent expression 

 were it not in such apparent contradiction with our every-day experience of ice. 



" Still the idea found its advocates. In a little book, published in 1773, and 

 entitled 'Picturesque Journey to the Glaciers of Savoy,' Bordier, of Geneva, 

 wrote thus : ' It is now time to look at all these objects with the eyes of reason ; 

 to study, in the first place, the position and the progression of glaciers, and to 

 seek the solution of their principal phenomena. At the first aspect of the ice- 

 mountains an observation presents itself, which appears sufficient to explain all. 

 It is that the entire mass of ice is connected together, and presses from above 

 downward after the manner of fluids. Let us, then, regard the ice, not as a 

 mass entirely rigid and immobile, but as a heap of coagulated matter, or as 

 softened wax, flexible and ductile to a certain point.' Here probably for the 

 first time the quality of plasticity is ascribed to the ice of glaciers. 



" To us, familiar with the aspect of the glaciers, it must seem strange that 

 this idea once expressed did not at once receive recognition and development. 

 But in those early days explorers were few, and the 'Picturesque Journey' 

 probably but little known, so that the notion of plasticity lay dormant for more 

 than half a century. But Bordier was at length succeeded by a man of far 

 greater scientific grasp and insight than himselft This was Rendu, a Catholic 



