PHILIPPINE SOILS. 



285 



the plants grow or the more exposed the location; on the other hand, 

 the greater the normal humiditj' the less the drying action. 



In the Philippines the average force of the wind is not high and will 

 scarcely influence ordinary crops. Typhoons often do a considerable 

 amount of damage, bnt it is comparatively seldom that a true typhoon 

 strikes the Philippine Archipelago. Of much graver consideration is the 

 question of the influence of winds on the growing of crops, for example 

 rubber, which are introduced from the absolutely still, tropical forest. 

 The rubber tree is extremely brittle and a small amount of wind will often 

 injure it enough to set it back considerably in its development. The 

 Weather Bureau reports are not sufficiently complete to warrant any 

 special study of winds, but I recommend that prospective planters pay 

 attention to this feature. 



Evaporation measurements which are comparable with evaporation from 

 the soil show that evaporation is approximately in proportion to the dura- 

 tion of the sunshine and is inversely proportional to the cloudy days and 

 rainfall, although it is somewhat influenced by the slightly increased 

 temperature during the summer months, as shovra by the following curve. 



?70 



210 

 ■^180 







^ 

















































\ 























\ 















/ 











\ 











^ 



5 



30 

 60 

 30 













\ 





\ 



^ 

































































































JAN. FCB. MAH. APR. MAY. JUNE. JULY. At/G. S£PT. OCT. NOV. 



Fig. 2. — Normal evaporation 1885-1907, Manila.'' 

 *From numbers, \w\ Rept. Dii: P. I. Weather Bur. (1907), 1.52. 



