AGASSIZ TO THE PRINCE OF CANINO. 357 



well know the impossibility of avoiding grave 

 errors in such a work, and that they can be 

 wholly weeded out only in a second and third 

 edition. I should have written sooner in an- 

 swer to your last, had not your letter reached 

 me on the Glacier of the Aar, where I have 

 been since the beginning of July, following 

 up observations, the results of which become 

 every day more important and more convincing. 

 The most striking fact, one which I think I 

 have placed beyond the reach of doubt, is the 

 primitive stratification of the nev^, or fields 

 of snow, — stratified from the higher regions 

 across the whole course of the glacier to its 

 lower extremity. I have prepared a general 

 map, with transverse sections, showing how 

 the layers lift themselves on the borders of 

 the glacier and also at their junction, where 

 two glaciers meet at the outlet of adjoining 

 valleys ; and how, also, the waving lines formed 

 by the layers on the surface change to sharper 

 concentric curves with a marked axis, as the 

 glacier descends to lower levels. For a full 

 demonstration of the matter, I ought to send 

 you my map and plans, of which I have, as 

 yet, no duplicates ; but the fact is incontest- 

 able, and you will oblige me by announcing 

 it in the geological section at Padua. M. 



