220 
if men are so disposed. While travelling through Belgium 
and France, to acquaint himself with the system of railways 
in those countries, he was much interested in the govern- 
ment steam guage for preventing undue pressure on the 
boilers. It was self-registering, so that at the end of the 
journey the amount of pressure at different stages could 
be seen. The engine-driver, however, by abstracting or 
adding a small portion of the mercury, could increase the 
pressure without the register giving any indication of the 
fact. The register acted, indeed, but only when the pres- 
sure was excessive. 
The Chairman was much pleased with the improved 
safety valve, and thought it approached as near perfection 
as possible. 
Mr. Nasmyth stated that six of these valves had been in 
action about eight months at the Oxford Road Twist Com- 
pany's works, Manchester, and that the managers were 
most willing to receive the visits of persons interested. 
ON THE CONTORTED STRATIFICATION OF THE DRIFT OF 
THE COAST OF YORKSHIRE. BY H. C SORBY, ESQ., F.G.S. 
The contorted stratification of the drift appears to have 
been little noticed or understood, until prominently brought 
forward by Sir Charles Lyell, in a paper read before the 
Geological Society in 1840, and subsequently published in 
the Philosophical Magazine. He then suggested that those 
seen on the coast of Norfolk had been produced by the 
action of stranded icebergs ; but the disturbed condition of 
the chalk has led many geologists to hesitate in adopting 
that theory. Since then the subject seems to have been 
much overlooked, so much so that, when the origin of the 
drift .was under discussion at the meeting of the British 
Association last year at Edinburgh, no mention whatever 
was made of the contortions ; and yet, as I hope to show, 
they are of such a character as to be of great value in 
