MEMOIR OF GUYOT. 701 



of the advance of the surface portion over that below, a point already 

 explained by him [by reference to friction at bottom].* 



Guyot opens his acconnt of the blue bands with the remark that, as 

 he had seen them only on one occasion, he dares not hazard an explana- 

 tion ; but his later sentences show that he was inclined to regard them 

 as a result of deposition, and to consider the varying inclinations in the 

 layers as due to subsequent disturbing action — that is, to the irregu- 

 larities of glacier movement, caused by friction and pressure under the 

 varying conditions of the glacier valley as to form and size. 



Whether right or wrong in these suggestions as to the bands, Guyot's 

 six weeks' work in the summer of 1838 was indeed fruitful. He had the 

 satisfaction of seeing his conclusions for the most part confirmed by the 

 facts collected by Agassiz, Forbes, and others, but not of receiving 

 credit for his work and original conclusions, except on one point, and 

 chiefly because of the want of proper publication. t 



* The cited paragraph iu the Systeme Glaciaire (p. 209) is as follows : "La direction 

 de ces couches coupait k augle droit la ligue de luarche (de pente) du glacier, leur 

 incliuatiou ddviait de 30° a 40° de la perpendiculaire vers la partie inf^rieure, comme 

 si la pente superhcielle gagnait de I'avance sur la partie iuf«rieure aiiisi que je I'ai 

 d^crit plus haut." The writer learns from Mrs. Arnold Guyot that this paragraph is 

 a part of the original manuscript, and that it was by oversight that it was not sent 

 to the Neuchatel Society in 1883 with the rest. 



t Kendu's " Th^orie des Glaciers de la Savoie " was published in 1841 (Mem. Soc. 

 Roy. Savoie, Chamb^ry, vol. x). Forbes's first letter from the Alps, announcing his 

 discovery iu August, 1641, of the " blue bands " in the Aar Glacier, was communicated 

 to the Royal Society of Edinburgh, December 6, 1841, and published in January in 

 Jameson's N. Phil. J., vol. xxxii, l?-42. Agassiz's first work on glaciers, " Etudes 

 sur les Glaciers," was published iu 1840. Neither of these publications mentioned 

 Guyot or his observations. 



Guyot's communication of 1841, published in the Altdorf Verhandlungen, was 

 drawn out by a discussion between Forbes and Agassiz relating to priority as to ob- 

 servations on the blue bands, and it was made just five days before Forbes's first letter 

 was lead in Edinburgh. Agassiz claimed credit for Guyot at the meeting in 1841, aa 

 a set-off against Forbes's claim, uud again, in the N. Phil. Journ., xxxiii, 265, 1842. 

 Forbes, in the following volume of that journal, xxxiv, 145, 1843, gives Guyot credit 

 for original discovery as regards the "blue bands." and speaks of his corresponding 

 with him ou the subject; and he repeats the acknowledgement to the "ingenious 

 l)rofessor of NeuchAtel," in his Travels through the Alps of Savoy, 1843 (first edition) 

 and 1845 (second edition), page 28. Desor, in the same journal, xxxv, 308, 1843, in a 

 paper on Agassiz's recent glacier researches, introduces a translation of Guyot's ac- 

 count of the banded structure, but cuts it short at the words, "opposite sides of a 

 trausverse valley," leaving off the explanatory remarks which follow. 



Tyndall, in his " Forms of Water" (1872, page 183), gives Guyot credit for pri- 

 ority ; and he cites, both iu this work and in his earlier " Glaciers of the Alps" (1856), 

 a translation of Guyot's account, ending it a sentence short of Desor's citation, with 

 the words, "certain calcareous slates" in place of Gnyot's "certain schistose lime- 

 stones" ; and on page 187 of "The Forms of Water," knowing only apart of what Guyot 

 had written, he does him more thau justice (admitting Tyndall's view to be estab- 

 lished) insaying that he " threw out an exceedingly sagacious hint when he compared 

 the veined structure to the cleavage of slate rocks," for the comparison in Guyot's 

 paper implies rather stratification from deposition. 



The tjrst detailed comparison of tliu " blue bands" to slaty cleavage in structure. 



