

THE ISLANDS AND THEIR POPULATION 25 
within the tropics, although the Batanes group, north 
of Luzon, stretches to within little more than a hundred 
miles of the limits of this zone. The temperature, as 
might be expected in an island climate, is remarkably 
equable. The warmest and coldest months in Manila 
differ by less than four degrees centigrade, and the 
greatest observed differences are only twenty-two 
degrees apart. The climate, with the exception of a few 
localities, is an unusually healthy one for the tropics. 
The rainfall is very variable, as might be expected from 
the irregular configuration of land and sea and the inter- 
spersed character of the mountain ranges. It is however 
generally fairly heavy, ranging from forty to one hun- 
dred and fifty inches a year, or from two to four times as 
much as in most parts of the temperate zone. Even 
those districts in the interior of Northern Luzon which 
are sometimes spoken of as semi-arid, must be under- 
stood as being so only in a comparative sense; they 
probably receive more rain than most parts of the 
United States. The precipitation is, on the whole, 
seasonal, but the seasons vary as much as the amount of 
rainfall. Some districts enjoy two rainy seasons, others 
only one. On some islands one flank is in the dry 
period while the other is in the wet. Such a thing as a 
completely arid season is however almost unknown in 
the Philippines. There is probably no district in which 
some rain does not normally fall during every month 
of the year. 
The combination of continuous tropical warmth and 
great precipitation produces the usual result; a rapid 
growth of a heavy and luxuriant vegetation. Practically 
the whole surface of the Philippines is naturally clothed 
with dense forest: the regions—like parts of northern 
Luzon—which are now more or less denuded, appearing 
to be so through human agencies. Over most of the 

