124 Canadian Record of Science. 
function of the Adirondack forests is found in the influence 
which they exert upon the streams heading among the hills 
of the Adirondack plateau, which distribute the heavy rain- 
fall of this region. As reservoirs of moisture, these forests 
are essential to the continued prosperity of the State. 
Their infinence is felt far beyond the limits of the State, 
and their destruction must be followed by widespread com- 
mercial disaster. The future of the rivers which flow from 
the Adirondack plateau may be judged by their past. 
Great changes have been noticed in these streams since the 
area of the Adirondack forests has been materially reduced. 
All the testimony which the commissioners have been able 
to collect upon this subject, indicates that the summer flow 
of the Adirondack rivers has been decreasing within the 
memory of men now living, from thirty to fifty per cent. 
These effects have a simple explanation. Any land area 
covered by forest has its rate of evaporation reduced by the 
shade thus afforded to the extent of 38 per cent., as com- 
pared with cleared lands; and the reduced evaporation 
under such circumstances so far exceeds the loss of water 
by transpiration, that there is an actual accumulation of 
water in the soil of forest-covered areas. Moreover, the 
organic matter accumulated in the growth of a forest, and 
the abundauce of moss induced by the moist shade thus 
afforded, serves as a retaining medium to hold the excess of 
water and allow it to gradually flow away into the st: cams. 
It follows from this, that streams rising in a dense forest 
will be distinguished by the uniformity of their volume and 
rate of flow; drought and flood are rare; springs abound. 
A removal of the forest destroys all the conditions upon 
which these phenomena depend. The stream experiences 
strong fluctuations in vclume and rate of flow; springs dis- 
appear, and drought becomes frequent ; while every rainfall 
is immediately precipitated down the steep hillsides, rap- 
idly merging into a flood, which carries disaster in all 
directions. 
