Report of the Besearches of M. Agamz. 161 



much still remains to be done upon this field, as novel as it is 

 vast. A cardinal point, which, above others, it is necessary 

 to know, is the difference between the summer and the winter 

 progress of the glacier. It will, undoubtedly, be very diffi- 

 cult to procure accurate data bearing upon this point, on ac- 

 count of the inconstancy of the seasons. But as we now 

 know the exact position of a great number of blocks at the 

 termination of last summer, we shall at least soon have 

 the power of appreciating the extent to which the mass 

 shall have advanced between this period and the ensuing 

 spring. We purpose to visit the glacier of the Aar with this 

 object, and to verify the observations of the previous autumn, 

 as soon as the snows shall have so far disappeared that the 

 blocks may be seen. By a second time measuring these points 

 at the close of summer, we shall know exactly the portion of 

 the movement which belongs to the hot season, and that which 

 belongs to the winter, comprised between the 5th of September 

 and the commencement of the spring. 



These, it is true, are but the first lineaments of a more 

 extended labour, which undoubtedly will one day be effected 

 with all the accuracy which the importance of the subject 

 merits. "We do not despair to see, ere long, a permanent ob- 

 servatory erected upon the margin of one of the great glaciers 

 of the Alps, in which may be prosecuted from day to day, 

 and from hour to hour, the progress of the glacier in all its 

 relations with meteorological phenomena. And as all inves- 

 tigation brings along with it its own reward, we have no 

 doubt that this will lead to satisfactory results. 



Observations on the changes of the Level of the Surface, — • 

 The large volume of water which daily escapes from the 

 glaciers at their terminal openings, clearly demonstrates that 

 a notable portion of their mass is carried away by melting. 

 Up to the present time, most observers have attributed this 

 melting, in part at least, to the effect of central heat. Not- 

 withstanding, when we ascend a glacier during a hot day, we 

 cannot fail to be struck by the quantity of small streams 

 which furrow the surface, and we are easily persuaded that 

 this quantity greatly exceeds that which escapes underneath 

 at the extremity of the glacier. But in this case, what be- 



VOL. XXXVl. NO. LXXI. JAN. 1844. L 



