PREFACE 



In offering — to employ " Mr. Pleydell's " phrase — my " poor 

 thoughts " on a subject at the present time uppermost in many men's 

 minds, I am anxious to record my sincere gratitude to the many 

 public authorities and private persons in this country and in France, 

 Belgium, the Netherlands, Italy, Eussia, Japan, and elsewhere, but 

 more specifically in Canada and its Provinces, and in the United 

 States, who have kindly supplied me, with unfailing readiness and 

 unvarying courtesy, with valuable and appreciated information. 



For obvious reasons I have arranged my subject-matter under 

 various heads, taking each aspect by itself. Such arrangement 

 necessarily entails occasional reference to the same fact under 

 different heads, as bearing upon different issues. 



The subject dealt with, the present importance of which is un- 

 questionable, has so many sides to it, that it appears to me that it 

 could not well be treated in any other way. 



H. W. W. 



May, 1921. 



