348 M. Escher de la Linth on certain Phenomena 



have been produced, has therefore followed exactly, in its 

 progress, this tortuous circumference. Now, of whatever 

 density we may suppose a current of water or mud to be, it 

 will always be less than that of stones, if it must possess a 

 considerable quickness. Stones, moving nearly in the direc- 

 tion of the current, will no doubt here and there go along the 

 walls of the bed ; but all those which reach the side-walls, 

 under whatever angle that may be, will be thrown back 

 towards the middle of the current, and it appears to me 

 altogether impossible that they can turn the least salient 

 angle.* 



Admitting, for an instant, that a current may produce fine 

 striae, it is then necessary to suppose, with regard to such as 

 are not rectilinear, that, commencing with one stone, they 

 have been continued by a second, a third, &c., which, by an 

 accident the most improbable, should have continued the 

 striae exactly from the point where it had been left by the 

 preceding stone. 



Again, when we consider that nearly horizontal furrows 

 shew themselves in the upper valley of the Aar, in a space of 

 many thousand feet in height, we must suppose, in order to 

 account for a simultaneous origin throughout the whole 

 height, a current, at least, of equal power, a current of a den- 



* Ifo one, as far as I know, has ever pretended to have observed stria) of the 

 nature in question, produced by actual currents. Stones set in motion by a 

 torrent have neither the power to produce nor to receive striae, because in roll- 

 ing along they only rub others, and are rubbed themselves. In fact, we never 

 find striae either in the beds of torrents or on the borders of lakes, not even in 

 eboulements, such as those of the Deut-du-Midi, and Combe-Mauvoisin, near St 

 Maurice. It is true that the stones in the latter sometimes exhibit white spots, 

 a little elongated (the longest I have seen did not exceed an inch and a-half ), 

 produced by the rubbing of the stones against each other ; but these spots ap- 

 pear to enable us expressly to distinguish between what can be produced in this 

 way by debacles and glaciers. We find not one of these horizontal striae on 

 the surface of the walls, exceeding six inches in length, the edges well defined ; 

 in short, striae cut as with a graving tool. We will seek for them in vain on 

 the surface of detached stones, while they are very frequent, and sometimes of 

 astonishing perfection, on the surface of the calcareous pebbles of the moraines 

 of existing glaciers (glacier of Sustenhorn, at the foot of the Meyenthal), and 

 in the erratic formations of all Switzerland. 



