PEOCEEDINGS 



OF THE 



CAMBRIDGE PHILOSOPHICAL 

 SOCIETY 



VOL. XX. PART IV 



[Easter Term 1921.] 



CAMBRIDGE 



AT THE UNIVERSITY PRESS 



AND SOLD BY 

 DEIGHTON, BELL & CO., LIMITED, 

 AND BOWES & BOWES, CAMBRIDGE. 



CAMBRIDGE UNIVERSITY PRESS, 



C. F. CLAY, MANAGER 



FETTER LANE, LONDON, E.C.4 



1921 



Price Eight Shillings and Sixpence Net 

 10 Novemier 192L 



