3 



VJO^ 



J^' '^7^ 



%\\xi%% 



TO 



THE BRITISH ASSOCIATION FOE THE 

 ADVANCEMENT OP SCIENCE, 



DELIVERED AT DUBLIN, 



14th August 1878, 



BT 



WILLIAM SPOTTISWOODE, M.A., F.R.S., LL.D., D.C.L., 



President, 



