real Stfucturp of Glacier Ice. 147 



surface. (2.), That had the occurrence of this structure to any 

 depth been a recognised fact subsisting previously in the mind 

 of M. Agassiz, v\ hether from his own observations or those of 

 another, Mr Heath and I would not have spent the whole after- 

 noon in what then seemed to Mr Heath " the very superfluous 

 endeavour to make out whether it was superficial or not." (3.), 

 What seems decisive in the matter, M. Agassiz claimed the 

 observation as his own in the letter to Humboldt, written in 

 October ; nor does he appear to have made any allusion to M. 

 Guyot in his communication on the same subject to the Societe 

 de Physique at Geneva, which occasioned M. Guyot to men- 

 tion his prior observation. 



Between M. Guyot and myself there remains nothing to ex- 

 plain. That gentleman has never contested the originality of 

 my observation, and I have never pretended to doubt the 

 reality of his, which, far from being made known to the world 

 by the publication of the proceedings at Porrentruy, seems to 

 have slipt entirely from the memory of the persons present 

 (including, I am informed, MM. Studer and Agassiz), whilst 

 every written proof of it remained in manuscript. Accord- 

 ingly, so soon as I had satisfactory evidence of the nature of 

 M. Guyot's communication, I hastened to write to him, and 

 assure him that I admitted his observation to be identical with 

 mine. This I did in the following terms: — 



Extract Tenth.— i^z-oni Profe&sor Forbes to Professor Guyot of 

 Neufchutel. 



" Edinburgh, 28?A Ajml 1842, 

 "My Dear Sir,— In a printed letter which M. Agassiz has forwarded 

 to me, I find a memorandum (printed for the first time) from j'our raanu- 

 script, containing- an account of the structure of the Glacier of the Gries, 

 observed in 1838, and stated to have been read at a meeting of Naturalists 

 at Porrentruy, in that year. 



" I have no hesitation in saying, that that note describes clearly a struc- 

 ture similar to that which I observed and pointed out to M. Agassiz and 

 Mr Heath, on the Glacier of the Aar, on the Oth of August last. 



" Whilst, then, I am most ready to do you full justice in respect to 

 the originality and clearness of your observation, you will, I doubt not, 

 as freely admit, that not having the pleasure of your acquaintance at the 

 time of my observing and ascertaining the existence and modifications of 

 this structure on the Aar Glacier, and never liaving heard, to the best of 



