PREFACE 



THE addresses printed in this volume were 

 delivered as public lectures at King's College 

 in the spring term of the present year. The 

 intention of the organisers of the course was to 

 place before the public the present position with 

 regard to the advancement of science in some of 

 its main branches, and to point out the directions 

 in which progress is actually being made or may 

 be hoped for in the near future. No uniformity 

 of treatment was expected, and each lecturer was 

 left to follow his own inspiration. Some have 

 attempted a more or less comprehensive survey 

 of the field allotted to them, while others have 

 concentrated their attention upon smaller areas. 



It is hoped that many who were unable to be 

 present at the lectures may be interested in this 

 brief review of the situation at a time when, in 

 spite of the disturbances due to the Great War 

 and the political and social unrest which have 

 followed it, the activity of scientific workers is 

 perhaps greater than at any previous period in 



the world's history. 



ARTHUR DENDY 



King's College, London 

 July 192 1 



