7i — 
total supply of rain from this cause alone cannot be very great, 
the trifling increase of quantity clue to the action of the for- 
ests cannot be worth taking into account. 
It may be said that trees have some influence upon the 
electric condition of the atmosphere, but to what extent the 
quantity of rain may be modified in consequence, it is not 
easy to determine ; it is generally considered, however, that 
electric changes are more often the consequence than the 
cause of condensation. 
Now as there is no cause of rain which may not be traced 
ultimately to one, as to the combined action of several of the 
processes which have been mentioned, it seems sufficiently 
clear that the extent of the forests has very little to do with 
the actual quantity of rain. 
It will be seen, further, that the permanent physical condi- 
tions under which the Island of Mauritius is placed, render it 
positively certain that large quantities of rain must fall, whe- 
ther forests exist or not. We have huge masses of rugged 
mountains, supporting elevated table lands in the centre of 
the island, the whole surrounded, to a great distance in every 
direction, by an ocean, yielding a constant and enormous sup- 
ply of vapour, under the influence of a tropical sun ; it neces- 
sarily results from these conditions, that from which ever di- 
rection the wind arrives, it comes in a very humid state. ’ 
almost always at a high temperature, such winds must t > - 
sit rain when passing over the elevated and cold parts of the 
island. 
It would have been very interesting to have procured re- 
liable statistical evidence shewing the quantity of rain that 
hasffallen at different periods, during a long series of years 
but that has not been possible, and it would require many 
years of carefully conducted observations, made simultane- 
ously in different parts of the island, to enable any positive 
deductions to be made from that source, as to the relation be- 
tween the extent of forests, and the quantity of rain. 
As far as the evidence of former legislation may be taken, 
it would appear that a periodical scarcity of water has always, 
from the earliest times, seemed to be quite as imminent as it 
is now ; and at very distant periods measures have been taken 
