» 
379 
characteristics of the vegetation is great.1' They will be considered in 
the order of their relative importance. 
Humidity.—Schimper ** bases his climatic formations mainly on rain- 
fall; those of the tropical lowlands fall under two heads—the tropical 
rainy and the tropical monsoon forests. The former are found in 
places where evergreen forests prevail during almost the entire year; the 
latter are those in which the dry districts are occupied by deciduous 
woodlands or savannahs. From the above it will be seen that the 
tropical rain forests are not necessarily those having precipitation which 
is uniform throughout the year; any alternation of wet and dry periods 
will show corresponding marked differences in the vegetation. 
TABLE I.—Average monthly rainfall, in millimeters, at Manila, 1865-1902. 
ees j | 
| 
| Dec. | Jan. Feb. | Mar. | Apr. | May. June. | July. | Aug. | Sept. | Oct. | Nov. Total. | 
| 
| 
| | oc Sa 
} $8] 2) 98} 18.6) 264 / 101.6) 247.6) 31 
| 
ee | arard ues: | oa a <) Sees A 
¢ Ben es 
361.2 | 374.7 | 191.8 | 186.5 1,988.3 | 
TABLE Il.—Rainfall, in millimeters, at three stations at Lamao compared with that for 
the same perio at Manila for a part of the year 1905. 
Dec. Jan. Feb. Mar. Apr. |May. June. July. Aug. Sept. 
See Ever er cetieemteest Onl euae eter ers pean i — —_—— | —— aca - epee gee 
Station T aes Rees Bae | 0 0.8) 127 | 881) 497.2 1,071.8 | 270.5 | 425.4 
| ; : 
Station 2 _..--..__.... “oie trea 6136 1 199.7 | ahd eee eee SRE el ee 
| Pte Bl el 2.2 6.8 273.3 70.1 1,084.3 | 1,401.6 | 294.6 | 709.2 
5A (t) prceaperness | 20.2 | 0} 28! 1.1 |18173,8 | 24 346.2 594.4 | 212.8 | 289.6 | 
TRESS. | | Fan of | | Pes See Ait + ey Se ee j 
In this and in the following tables station 1 is at sea level, station 2 
at an elevation of 85 meters, 4 kilometers inland, and station 3 at an 
elevation of 640 meters, 13 kilometers inland. These two tables con- 
clusively show well-marked wet and dry seasons both for Manila and the 
stations at Lamao. So slight is the rainfall during the dry season that 
one is surprised to find a forest in which the evergreen is as characteristic 
as the deciduous element and not a completely deciduous one to cor- 
respond with this climatic condition. During the season of little or no 
"The necessity of a base for comparative climatic data can not be too strongly 
emphasized. Isolated readings without such a comparison are practically worth- 
less; on the other hand, with such data their value becomes nearly as great as 
would be that of continuous records. However, the readings must be made 
simultaneously. For the Manila records up to 1903 given here, see Algué, Rev. 
Jose. Climate. Census of Philippine Islands, 1903, 1: 87. I am indebted to 
R. Meyer, T. Hanley, and other employees of the Bureau of Forestry for assistance 
in the collection of climatic data. 
“1. ¢., 160, 261. 
* The excessive rainfall for April is the highest ever recorded. It is mainly 
the amount which fell during the typhoon which visited the Islands on the 30th 
of that month. 
