FORESTRY 195 



balls, gutta-percha is the one substance which furnishes 

 satisfactory insulation for submarine cables. 



53 A. Forestry. You have noted that the stems of 

 trees, both on account of their usefulness and on account 

 of their beauty, are of great importance to man. That 

 division of science which concerns the culture of trees, and 

 especially of their stems, is called forestry. (See page 52.) 



A . Importance of Forests. Primarily forests are im- 

 portant as sources of timber. Other things add to their 

 value and to the great need for their preservation. One 

 of these things is the fact that forest soil is very retentive 

 of moisture ; it acts as an absorbing reservoir in which the 

 water after heavy rains is held, and from which the excess 

 of water runs away slowly. This tends to prevent floods 

 which wash away valuable soil and in other ways cause 

 great damage. Man's enjoyment of forests also adds 

 much to the desire and need of all of us that they be not 

 ruthlessly destroyed. 



B. Aims of Forestry. It is the aim of forestry not merely 

 to preserve forests, but so to manage them that they will 

 be continuously productive. Foresters learn by careful 

 study the habits of growth and reproduction of trees, and 

 make plans for forest management which will insure the 

 usefulness of the forests to future generations as well as 

 to this one. The Bureau of Forestry of the United States 

 Government manages large tracts of public land which have 

 been set aside as forest reservations. The lumbermen 

 who cut timber on these reservations do so under gov- 

 ernment direction, and their permanent productivity is 



