Proceedings. 37 



" The intensity of transmitted light when the coefficient of 

 transmission is a function of the time." 



Mr. William Brockbank, F.L.S., F.G.S., and Mr. C 

 E. DE Range, F.G.S., read the first part of a paper on 

 *' The Geological Section exposed by the railway cutting at 

 Levenshulme." The paper was illustrated by an elaborate 

 coloured chart of the whole section drawn to scale. A dis- 

 cussion ensued, in which Mr. Pergy F. KENDALL, Mr. J. W. 

 Gray, and Dr. G. H. Bailey took part. 



Mr. William Thomson, F.R.S. Ed., F.C.S., read a 

 paper by himself and Mr. FREDERICK Lewis on "The 

 action of various chemical compounds and metals on india- 

 rubber," and exhibited samples illustrating the remarkably 

 deleterious influence of copper salts. 



