4b'0 Geological Society. 



Thus equation (6) p 270 of my paper, which in the full 

 notation should be written s ap /s\ }p = cr a J(TQ^, is established by 

 another method. This equation, as already stated, is of 

 theoretical interest, and I hope, when suitable experiments 

 have been made, it will throw light on the action of dissimilar 

 molecules on one another both in the liquid and in the gaseous 

 states. 



I am, 



Yours faithfully, 



Berkeley. 



XLIIL Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 

 [Continued from p. 384.] 



May 2nd, 1917.— Dr. Alfred Harker, F.R.S., President, 

 in the Chair. 



HPHE following communications were read : — 



1. ' Supplementary Notes on Aclisinn De Koniuck, and 

 Aclisoides Donald, with Descriptions of New Species.' By Jane 

 Longstaff (nee Donald), E.L.S. 



2. ' The Microscopic Material of the Bunter Pebble -Beds of 

 Nottinghamshire and its Probable Source of Origin.' By Thomas 

 Harris Burton, F.G.S. 



As shown by the distribution of the heavy minerals, com- 

 bined with (a) the direction of the dip in the cross-bedding, 

 (b) the evidence adduced by boreholes and shaft- sin kings, a main 

 current from the west is indicated. In the neighbourhood of Gorse- 

 thorpe this current bifurcated, one division flowing eastwards, the 

 other running south-eastwards. 



A large quantity of the material is derived from metamorphic 

 areas, as shown by the presence of staurolite, shimmer-aggregates, 

 microcline, sillimanite, and kyanite. 



The source of the bulk of the material is probably Scotland, 

 and the westward adjoining vanished land, from rocks similar in 

 the main to those of the metamorphic and Torridonian areas known 

 in that country. Minor supplies came from the neighbouring 

 Pennine ridge, and from other surrounding tracts of high land. 



The material was transmitted by means of a north-western 

 river and its tributaries, flowing into the Northern Bunter basin. 

 During certain flood-periods this river overflowed across Derby- 

 shire, carrying its load of sediment, much of which was deposited., 

 as it is now found, in the Pebble-Beds of Nottinghamshire. 



