142 Professor Forbes's Thirteenth Letter on Glaciers, 



central one, marked (2.), was placed on the moraine descend- 

 ing from the Jardin. No. (1.) was nearly midway between 

 it and the northern shore at station W. Here there is a 

 hollow in the surface of the glacier, which was thickly covered 

 with snow in the end of July. At (2.) and (3.) the ice was 

 quite bare and more level, but at the same time more cre- 

 vassed, — the crevasses being remarkably well defined, nar- 

 row, rather deep, and rectilinear, or slightly curved, not un- 

 even. No. (3.) was 1068 feet beyond (2.) No. (1.) was 533 

 feet northwards from No. (2.), and was 687 feet distant from 

 the northern shore. These distances were ascertained partly 

 by direct measurement, partly trigonometrically. These three 

 points were fixed in the transverse visual line from W. on 

 the 24th July, by forming three perfectly round and vertical 

 holes, no less than 5 feet deep, by means of an iron jumper. 

 Being examined on the 31st July, after a lapse of six days 

 and seventeen hours, the motions were found to have been — 



July 24, 5 P.M. to July 31, 10 a.m., 



Or daily in inches, . . 12*9 15'7 12-9 



By a remarkable coincidence, the 1st and 3d stations had 

 been so symmetrically chosen, as to have precisely the same 

 velocity. The middle point, as usual, moved fastest. 



This velocity will be considered to be large when we recol- 

 lect the great height of the glacier above the sea, and the 

 small inclination of its surface at this place. On the other 

 hand, it is a natural consequence of the theory which regards 

 this narrow outlet as the overflow of a vast reservoir, in 

 which snow has peculiar facility in accumulating. 



I shall now mention a truly remarkable circumstance con- 

 nected with the velocity of the discharge of the icy stream 

 which empties the basin of Talefre. I was apprised by David 

 Couttet, on the 23d July last, on his return from looking for 

 crystals on the moraines of the Glacier of Talefre, that he had 

 found opposite to Les Egralets (see the map), or where the 

 ice of the Talefre joins the Glacier de Lechaud, some frag- 



