1 CLIMATE AND ASPECTS OF THE EQUATORIAL ZONE 231 
conditions. Whether we are at Singapore or Batavia, in the 
Moluccas or New Guinea, at Para, at the sources of the 
Rio Negro, or on the Upper Amazon, the equatorial climate 
is essentially the same, and we have no reason to believe that 
it materially differs in Guinea or the Congo. In certain 
localities, however, a more contrasted wet and dry season 
prevails, with a somewhat greater range of the thermometer. 
This is generally associated with a sandy soil, and a less dense 
forest, or with an open and more cultivated country. The 
open sandy country with scattered trees and shrubs or occa- 
sional thickets, which is found at Santarem and Monte-Alegre 
on the lower Amazon, are examples, as well as the open 
cultivated plains of Southern Celebes; but in both cases the 
forest country in adjacent districts has a moister and more 
uniform climate, so that it seems probable that the nature of 
the soil or the artificial clearing away of the forests, are 
important agents in producing the departure from the typical 
equatorial climate observed in such districts. 
Effects of Vegetation on Climate 
The almost rainless district of Ceara on the north-east coast 
of Brazil, and only a few degrees south of the equator, is a strik- 
ing example of the need of vegetation to react on the rainfall. 
We have here no apparent cause but the sandy soil and bare 
hills, which, when heated by the equatorial sun, produce ascend- 
ing currents of warm air and thus prevent the condensation of 
the atmospheric vapour, to account for such an anomaly ; and 
there is probably no district where judicious planting would 
produce such striking and beneficial effects. In Central India 
the scanty and intermittent rainfall, with its fearful accom- 
paniment of famine, is perhaps in great part due to the 
absence of a sufficient proportion of forest-covering to the 
earth’s surface ; and it is by a systematic planting of all the 
hill-tops, elevated ridges, and higher slopes that we shall 
probably cure the evil. This would almost certainly induce 
an increased rainfall; but even more important and more 
certain is the action of forests in checking evaporation from 
the soil and causing perennial springs to flow, which may be 
collected in vast storage tanks and serve to fertilise a great 
extent of country ; whereas tanks without regular rainfall or 
