PREFACE TO THE SECOND EDITION 
The marked development, during the past decade, in power 
logging machinery and methods has made it desirable to revise 
the first edition. A chapter has also been added on the use of 
crawler tractors in logging work because their rapid adaptation 
to the loggers' needs indicates the extensive adoption of this form 
of equipment. This chapter has been prepared by A. Koroleff, 
a Russian forest engineer, who has spent much time in studj-ing 
the use of this kind of equipment on logging operations in the 
United States. 
The subject matter has been rearranged, in part, to better 
meet the needs of the teacher and student and much of the text 
has been rewritten. 
Acknowledgment is here made to those whose constructive 
criticisms and suggestions relating to the revision of the first 
edition have proved invaluable, and also to all others who have 
aided in the preparation of the text. 
R. C. BRYANT 
New Haven, Conn. 
September, 1923. 
