388 Scientific Intelligence — Meteorology. 



32° Fahr. Such, the author stated, must necessarily be the case, 

 unless the conductive power of ice was greater than it was deemed 

 possible that it could be. He considered the sub-glacial currents as 

 powerful agents in the disintegration of the lower surfaces of glaciers, 

 especially near their lower extremities. The results of Professor 

 Forbes's observations on the motion of the Mer de Glace of Mont 

 Blanc, afforded, as regards that glacier (and, by inference, as regards 

 all other glaciers) a complete refutation of the theories which attri- 

 bute glacial movements to any expansion or dilatation of the ice. 

 The Professor had, however, put forth a new theory, which agreed 

 with that offered by Mr Hopkins in attributing glacial motion to the 

 action of gravity, but differed from it entirely as a mechanical theory 

 in other respects. The Professor appeared to reject the sliding 

 theory of De Saussure, on account of the difficulties already men- 

 tioned (which were now removed by the above experiments), and 

 assigned to the mass of a glacier the property of plasticity^ or 

 semifluidity, in a degree sufficient to account for the fact of its de- 

 scending down surfaces of such small inclination. According to 

 this theory, the motion was due to the small cohesion of one par- 

 ticle of glacial ice to another. Mr Hopkins stated his conviction 

 that the internal cohesion of the mass was immensely greater than 

 its cohesion to the surface on which it rests, whenever the lower 

 surface is in a state of disintegration. It was perfectly consistent 

 with this conclusion, to assign to the glacier whatever degree o^ plas- 

 ticity might be necessary to account for the relative motions of its 

 central and longitudinal portions under the enormous pressure to 

 which, according to his theory, he shewed it might be subjected. 

 Such relative motions, however, were probably facilitated more by 

 the dislocation than the plasticity of the mass. Sufficient, he trusted, 

 had been advanced to prove that the sliding theory assigned a cause 

 adequate to the production of all the observed phenomena of glacial 

 movements. — Athenceum, 



3. On the Transport of Erratic Blocks and Detritus from the Alps 

 to the Jura. By Mr Hopkins. — With respect to the transport of erratic 

 blocks and detritus from the Alps to the Jura, Mr Hopkins observed 

 that the greatest height which glaciers had formerly attained in the 

 valley of the Rhone (whence a large portion of the erratics had been 

 derived), appeared to be well defined by lateral moraines and polished 

 rocks, while the greatest height at which these blocks had been de- 

 posited on the Jura was also well defined. Thus, according to M. 

 Charpentier, the Rhone glacier must have risen, at the mouth of the 



