xxvi Proceedings. {March 21st, i8gg. 



Ordinary Meeting, March 21st, 1899. 

 J. Cosmo Melvill, M.A., F.L.S., President, in the Chair. 



The thanks of the members were voted to the donors of the 

 books upon the table. 



Dr. C. H. Lees described the Wehnelt current-interrupter, 

 and gave an account of some experiments he had made. The 

 effect of substituting it for the mechanical make and break of 

 an induction coil used for producing Rontgen rays is that the 

 action of the Rontgen ray tube is intensified, but the anti- 

 cathode is rapidly heated, and seemed in its hot state to be 

 much less effective in producing the rays. 



Mr. George Wilson, M.Sc, read a paper entitled 

 " Experiments on the Relation between Uniform Stress 

 and Permanent Strain in Annealed Copper Bars and 

 Wires." 



Messrs. F. H. Bowman, Stanton and Thorp took part in the 

 discussion which followed. 



This paper is printed in full in the Memoirs. 



