72 Geological Society : — 



longitudinal magnetic states produced by the two currents coex- 

 isted in the same substance. The torsional influence of the ex- 

 cited helix is distributed equally throughout its length ; so also is 

 that of the current in the bar. AH the torsions are closely related 

 to the well-known electric sounds, and to particular positions and 

 internal movements of the particles of the iron. 



Signs of electrotorsion were obtained with a bar of nickel, but 

 not with wires of platinum, silver, copper, lead, tin, cadmium, 

 zinc, magnesium, aluminium, brass, or German- silver, nor with 

 a thick rod of zinc, or a cord of gutta percha. 



GEOLOGICAL SOCIETY. 



[Continued from vol. xlvii. p. 462.] 



June 25, 1873. — Joseph Prestwich, Esq., F.R.S., Vice-President, 



in the Chair. 



The following communications were read : — 



1. " On six Lake-basins in Argyllshire." By His Grace the Duke 

 of Argyll, K.T., F.R.S., President. 



The author referred to the part ascribed to glacial action in the 

 formation of lake-basins, and described the basins of six lakes in Ar- 

 gyllshire, the characters presented by which seemed to him incon- 

 sistent with their having been excavated by ice. Among these lakes 

 were Loch Fyne, Loch Awe, Loch Leckan, and the Dhu Loch. The 

 upper part of Loch Fyne was said to be cut off from the rest by a bar 

 of islands, with only one or two deeper passages. The country about 

 Loch Fyne was described as consisting of Upper and Lower Silurian 

 mica-slates, which have been violently contorted, their normal strike 

 being indicated by the direction of the valleys. Loch Fyne occupies 

 a niche in the slope of the rocks, having an escarpment on one side 

 and the shelving strata on the other. The existence of a fault along 

 the line of the loch was probable, but could not easily be ascertained. 

 Its greatest depth in this part was said to be 84 fathoms. Its 

 banks show marks of glaciation, whereon the surface is well adapted 

 for their preservation ; the strongest marks are on those rock-faces 

 which look up the loch. Between Loch Fyne and Loch Awe the 

 mica-slates are interstratified with granite, which the author be- 

 lieved to have been forced up between the plains of stratification by 

 the pressure caused by the falling in of the mica-slates, as frag- 

 ments of the latter rock are imbedded in the granite. The author 

 described the different structure of the two banks of Loch Awe, the 

 upper part of which seemed to him to lie in a synclinal trough ; and 

 its waters were only prevented by a low col from finding their way 

 to the Atlantic in this direction, instead of from the lower end. 

 The formation of the basin of Loch Awe seemed to the author to be 

 due solely to geological structure, as was also the case with another 

 lake beyond the head of Loch Awe. The surrounding country was 

 said to be full of smaller lake-basins, the formation of which might 

 be due to the denudation of the softer mica- schists lying below the 



