136 Professor Forles on the First Discovery cf the 



crevasses, and was dislocated by them, as in the margin, and, 

 therefore, must have been anterior to their formation. 



Let us hear the evidence of INIr Heath and M. Agassiz, the 

 only witnesses present besides the guide. 



Mr Heath wrote to me thus, on sending him the above 

 statement of facts : — 



Extract First. — licv. J. 31. Heath to Professor Forhes, (printed 

 bj Mr Heath's permission.) 



Trinity College, C/A March 1042. 



" * * But those who were there this summer have very different 

 evidence that this was a new fact. I remember when it was first re- 

 marked, Agassiz said he had seen it before, but not to sucli an extent. 

 That it had a j^eculiar relation to the medial moraines, and would not 

 be found in the centre of the glacier ; tliat it was only superficial, and 

 owing, as he believed, to the sand which placed itself in jiarallcl straight 

 lines, and produced these incisions by melting the ice. The afternoon 

 was taken up in what I then thought a very superfluous endeavour to make 

 out whether it was superficial or not, and I believe he maintained the 

 contrary opinion until the discovery of the great hole of which j'ou have 

 given a drawing." 



It will be observed, then, that the whole question lies in 

 this, Wliether the lined appearance of the ice was due to an 

 inequality of melting, occasioned by a linear arrangement of 

 sand on the surface, washed from the moraines, and inter- 

 cepting here and there the sun's rays I — or. Whether it was 

 occasioned by the unequal action of the weather on alternat- 

 ing vertical bands of friable and of compact ice, of which the 

 glacier is composed. M. Agassiz appears, upon Mr Heath's 

 testimony and my own, to have taken the former view, whilst 

 I took the latter. According to him, the ice was striated on 

 its surface, because the sand lay in lines ; according to me, the 

 sand lay in lines, because the ice has a veined structure tltroiigh- 

 out its mass. 



M. Agassiz, the otJier witness, admitted as much himself, 

 when I requested him to say whether the above-cited facts 

 were accurately stated or not. In a letter to me, dated 29th 

 March 1842, he says,— 



