FORESTS, RESERVOIRS, AND STREAM FLOW 269 
and many people ascribed this fact to deforestation, which allowed the 
water to find its way more quickly into the lakes. During the Nineties, 
there was a period of general subsidence, occasioning considerable 
anxiety, and it was frequently asserted at that time that this was due 
to deforestation, which was drying up the streams. For some years 
now the Lakes have been rising, Ontario being the highest in 40 years; 
and with another wet year the levels will almost reach record heights. 
The long record.of the Danube floods, already referred to, is another 
example. Almost invariably high floods would follow each other for 
several years in close succession, and then would come long intervals 
of. ordinary high waters. 
These periodic changes are not, of course, due at all to the presence 
or absence of forests, for they occur just the same whether forest con- 
ditions remain unchanged or not. It is an order of Nature not at all 
understood, but nevertheless fully established as a fact. Just now we 
are in an era of high precipitation and consequently of high waters. 
There is a disposition to “view with alarm” these exaggerated condi- 
tions. Rarely does one stop to think how far better it is to the country 
to have these wet periods, even with all their floods, than the dry 
periods that will surely follow. A single dry year may cause more 
loss to the country through the shrinkage of crops than the floods of 
an entire cycle of wet years. 
Related to the subject of precipitation is that of evaporation as 
affecting the quantity of water that remains upon the ground. Gen- 
erally speaking, the surface evaporation in summer should be greater 
in the open than in the forest because of the more direct action of the 
sun and wind; but in the height of summer the forests arrest precipi- 
tation to such an extent in the leaves and humus, that more of it 
escapes through evaporation than in the open. The effect of forests 
upon evaporation through the medium of their leaves finds its counter- 
part in the similar action of the growing crops that overspread defor- 
ested areas. As already pointed out, the forests of the mountains 
increase the evaporation from snow very materially. 
Where the balance lies among all these conflicting influences af- 
fecting precipitation and evaporation it is impossible to say, and 
when the records are examined it must be admitted that they afford 
no answer. So far as the researches of Science have yet determined, 
the presence or absence of forests cuts no figure in climatic conditions, 
