16 



gum (E. corynocalyx), blackbutt (E. pilularis), and red ma- 

 hogany (E. resinifera). The jarrah and the red mahogany are 

 especially highly esteemed for furniture. The blue gum (E. 

 globulus), and the swamp mahogany (E. robusta), and the 

 lemon-scented gum (E. citriodora) are good all-around timber 

 trees, but they are inferior to the trees mentioned above. The 

 blackbutt and the blue gum are especially liable to warp and 

 twist unless carefully seasoned, and are objectionable for this 

 reason. The blue gum (E. globulus), the jarrah (E. niargin- 

 ata), and the red mahogany (E. resinifera) are especially well 

 adapted for wharves and piling because they resist to a large 

 extent the attack of the teredo, which destroys many other kinds 

 of timber. 



A more complete table of the uses of wood of the various eu- 

 calypts may be found in the Appendix. 



Watershed Protection. 



An abundant and regular flow of water is essential to the 

 successful raising of crops in Hawaii, since, in spite of heavy 

 rainfall in certain localities in the Islands, a large proportion of 

 the cultivated land is under irrigation. Many of the richest 

 sugar cane fields are absolutely dependent on an adequate supply 

 of water during the dry season. 



There are few places in the world where the relation between 

 forests and waterflow is so intimate as it is in certain parts of 

 Hawaii. Because of the climatic conditions, the physiographic 

 features, and the geologic formation prevailing here the destruc- 

 tion of the forest, especially on the steeper slopes and at the 

 higher elevations, is almost immediately followed by a marked 

 decrease in surface run-off during dry seasons, while in heavy 

 rains the water runs down in torrents, washing and gulleying 

 the mountain sides. The native forest which once covered the 

 mountains with its numerous ferns, moss, vines and brush, was 

 an ideal watershed protection, acting as a sponge in catching 

 the rain and retaining the water for a long time. No matter 

 how dry the air, the floor of the forest was always damp and the 

 springs were always full. In many places, however, the forest 

 maintained itself with great difficulty ; and in consequence of 

 the introduction by the white man of cattle, Hilo grass, lantana 

 and other animals and obnoxious plants the native forest is 

 rapidly disappearing and the denudation of the mountain slopes 

 is becoming more and more serious. 



A systematic artificial reforestation of denuded slopes on im- 



