COPYRIGHT 



jhirst Published igo'i 



Second Edition {revised) 1907. 



Reprinted 1908, 1909. 



American Edition 1909. 



German Edition 1910. 



Swedish Edition 191 1. 



Third Edition {entiely rewritten and much enlari^ed) 191 1. 



Fourth Edition {revised) 1912. 



Russian Edition, 1913. 



Fifth Edition, 1919. 



Japanese Edition, 19 19. 



Sixth Eaition, 1922. 



PRINTED IK GREAT BRITAIN 



