PREFACE 
THE subject matter of this book was briefly dealt with by 
me in three Chadwick Public Lectures, which were de- 
livered at the Royal Society of Arts, London, in May 1917, 
under the title of “ Forests, Woods, and Trees in relation to 
Hygiene.” 
An effort is made in this book to interest the statesman, 
the student of economics, the engineer, the physician, and 
the layman, as well as the forester, in certain aspects of 
forests and trees, about which vague notions are prevalent. 
An endeavour is made in the first two chapters to recognise 
and describe the far-reaching influences of forests and trees 
on climate, flow of water, erosion of the soil, shelter from 
wind, purity of air and water, etc. Such influences affect 
directly the health and comfort of man. The value of 
forest districts as sites for sanatoria and the history and 
utility of parks, open spaces, and trees in towns are then 
discussed. The afforestation of the desolate pit mounds in 
the Black Country and other districts is shown to be a 
movement of great interest, especially when, as in some 
cases, it is taken up by school children, 
One effect of the war has been to bring home to think- 
ing people the extreme importance of afforestation. The 
ancient warning, “La France périra faute de bois,” is now 
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