ACKNOWLEDGMENT 



In preparing this book the authors have made frequent 

 reference to the publications of the U. S. Forest Service, the 

 Society of American Foresters and many State forestry publi- 

 cations. They acknowledge especial indebtedness to the 

 writings of William B. Greeley, Raphael Zon, Earle Clapp, 

 William Sparhawk, E. A. Smith, Gilford Pinchot, Wilbur 

 R. Mattoon, E. W. Berry and Charles Boyce. 



Additional thanks for review of manuscript are due to 

 Raphael Zon and William Sparhawk. 



Line drawings are by Garnet Jex, staff artist of Nature 

 Magazine. 



Illustrations not otherwise credited are by courtesy of the 

 United States Forest Service. 



