The Edinburgh New Philosophical Journal. 247 



III. If only one disc be connected with an ore-point, 

 and the other with the timbering, or held in the hand, 

 there is no effect produced. 



IV. If an ore-point is connected with masses of ore 

 already won, a current sometimes manifests itself, some- 

 times none. 



V. When an ore-point is connected with a non-me- 

 talliferous rock, frequently no current — frequently, however, 

 a current, though always feeble, yet distinct, — takes place in 

 the connecting wire. 



In several cases Professor Reich found no trace of de- 

 viation in the force of the electric current. 



A paper on the Glaciers of the Alps, by M. J. Andre 

 De Luc, from the Biblioth. Universelle de Geneve, 1889, 

 forms the next article. M. Agassiz, in a paper which re- 

 cently appeared in the same work, ascribed the movement 

 of glaciers to the expansion of water ; but M. De Luc con- 

 siders that water infiltrating into the fissures beyond a cer- 

 tain depth cannot be frozen, and consequently cannot ex- 

 pand, since ice is so bad a conductor of caloric that water 

 at a depth of a few feet in it will not congeal. He ascribes 

 the movement of Glaciers to two causes, namely, the ac- 

 cumulation of snow on their upper surface, and the melting 

 of the ice. 



Previous to the year 1812, the lower extremity of the 

 Glacier des Bossons was surrounded with pines, the size 

 of which indicated that they must have been in undis- 

 turbed possession of the soil for ages. But in 1812, when 

 a succession of six cold summers commenced, the glacier made 

 successive advances both in length and breadth, and this 

 progression continued till 1818, when it had destroyed the 

 pine forests and covered meadows which it had never 

 reached before. In 1820 it began to retire, and in 1822 

 had retired considerably, and left the surface of the meadows 

 covered with blocks of stones and rocks of great size. 

 M. Agassiz supposes that by rolling stones beneath them, 



