SCIENCE PROGRESS 



IN THE TWENTIETH CENTURY 



A QUARTERLY JOURNAL OF 



SCIENTIFIC WORK 



& THOUGHT 



NO. 13. 



JULY 1909 



EDITORS 



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

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

 W. G. FREEMAN, B.Sc, A.R.C.S., F.L.S. 



LONDON 

 JOHN MURRAY, ALBEMARLE STREET, W. 



1909 



Price 51' net 



VOL. IV 



