

SCIENCE PROGRESS 



IN THE TWENTIETH CENTURY 



A QUARTERLY JOURNAL OF 



SCIENTIFIC WORK 



& THOUGHT 



NO, 28. APRIL 1913 



EDITORS 



H. E. ARMSTRONG, Ph.D., LL.D., F.R.S. 

 J. BRETLAND FARMER, M.A., D.Sc, F.R.S. 



LONDON 

 JOHN MURRAY, ALBEMARLE STREET, W. 



1913 



Price 5/- net 



VOL. VII 



