PRECIPITATION OVER WOODS AND OPEN FIELDS. 



115 



To eliminate this, compare the stations mentioned with other German 

 stations of about the same elevation. For this purpose the rainfalls at 

 192 stations given by Dr. van Bebber were used, and these and the 

 previous ones were combined for each hundred meters. 



This comparison throws some light not only on the amount of sur- 

 plus over woods, l)ut on the distribution of it. It increases rapidly 

 with the elevation. For 328 feet (99.9 m.) or under, it is but 1 per cent; 

 from this to 1,.300 feet (396 m.) it is 7 to 14 per cent; between 1,950 

 (594 m.) and 2,270 feet (092 m.) it is 19 per cent; between 2,270 (692 m.) 

 and 2,028 feet (801 m.) it is 41 per cent; and above the last the sur- 

 plus appears to be 84 per cent, or the precipitation over forests is nearly 

 doubled. 



It is easy to show that, in general, heavily wooded districts have a 

 higli rainfall, as compared with similar districts Avithout forests. This 

 is notably true in India, as shown by Dr. Brandis and others. It is 

 enough to say that the heaviest known rainfall occurs in one of the 

 densest and most extensive known forests, that of the middle and 

 lower Brahmaputra. But in all these cases it is more probable that 

 the forest exists because of the rainfall, rather than vice versa. A 

 case which is more favorable to the influence of forests on rainfall is 

 given by Dr. Woeikoff, depeuding on the rainfall distribution on Java 

 and Celebes. Java has extended and dense forests in the south and in 

 the southwestern interior, while the north coast has been largely defor- 

 ested. The station Tjilatjap on the south coast is at a distance from 

 mountains. Its annual rainfall is 182.3 inches (4,630 mm.). That for 

 three stations on the north coast (Batavia, Tegal, and Samarang) is 

 78.4 inches (1,991 mm.) or 43 per cent only. In this region the north 

 side of the islands is the weather side for the northwest monsoons and 

 should have, at least from December to March, more rain than the 

 south side, because this wind descends to reach the latter. As ^ mat. 

 ter of fact there falls in these months — • 



At Tjilatjap 45.7 inches (1,161 mm.) 



At the north coast stations 1.3.3 inches (1,100 mm.) 



or almost as much on the lee side as on the windward, while there 

 should be very much less on the latter, . 



