26 SECTIONAL ADDRESSES. 



course in the presence of matter the curvature is far stronger still. So 

 the universe is like the earth, on which the local curvature of hills and 

 valleys is far greater than the general curvature of the terrestrial globe. 

 In concluding these remarks I ought perhaps to apologise for having 

 said nothing about the relation of general relativity to the new wave- 

 mechanics. My excuse must be that, at the request of the Secretary of the 

 British Association, this address was sent to the printer many weeks 

 before the meeting ; and the wave-mechanics is developing so rapidly 

 that, as one eminent worker has declared, anything printed is ipso facta 

 out of date. 



