FIRST EDITION 



Copyright, 1915, by 

 PRINCETON UNIVERSITY PRESS 



Published February, 1915 

 Second Printing, June, 1915 



REVISED SECOND EDITION 



Copyright, 1916 



Published May, 1916 



Second Printing, August, 1917 



Third Printing, March, 1918 



REVISED THIRD EDITION 



Copyright, 1919 



Printed in the United States 

 of America 



