IT PREFACE. 



those works; and to the American Society of Civil Engineers and the Association of 

 Knjjineering Societies for similar courtesies; and to the Commission for the canali- 

 zation of the Elbe and Moldau in Bohemia (M. W. Rubin, Chief Engineer of Construc- 

 tion) for information and photographs of that system of improvements. 



JULY, 1904. 



