H 
GENERAL INTRODUCTION. 
ing January, February, and March. Notwithstanding these facts, 
diseases of the lungs are rare among the inhabitants, and even the 
severe winters have proved of benefit to those consumptives that have 
remained here throughout the entire year. 
The mean annual rain-fall exceeds that of most portions of the 
State, and is estimated by Mr. Colvin, from the available data, to be 
45.18 inches (1,149 mm.) for the entire region. The mean annual rain- 
fall over the whole State is 41.94 inches (1,063 mm.).* 
There are two elements that tend to increase the humidity of this 
region : 1st, its mountainous character, for mountains always act as 
condensers of moisture; and 2d, its heavy covering of forests, for 
dense vegetation protects the underlying soil and rock from the direct 
action of the sun, and keeps the temperature lower — thus favoring 
condensation and the precipitation of excess moisture. 
“A deciduous tree, during the season when in foliage, is constantly 
drawing from the earth and giving off from its leaves a considerable 
amount of moisture, and in some cases this amount is very great. 
This change of state, from a fluid to a gaseous condition, is a cooling 
process, and the air near the surface, being screened from the sun and 
from the winds, becomes by this means so humid, that a rank suc- 
culent vegetation often springs up and thrives, which in an open field 
would wither and perish in an hour. "*j* 
Now it is well known that there is, in nature, no such thing- as a 
<L> 
perfectly dry atmosphere, for at all times, and in all places, it is laden 
with less or more aqueous vapor in a state of suspension. The higher 
the temperature the greater the capacity for carrying moisture, and 
consequently the more moisture required to produce saturation — by 
which term we understand the maximum quantity of watery vapor 
that a definite amount of atmospheric air can contain at any given de- 
gree of temperature. No evaporation whatever can take place from any 
surface in a saturated atmosphere, and any cooling of such an atmos- 
* Meteorology of New York State, Second Series, F. B. Hough, 1872, p. ix. 
•j Hough’s Report on Forestry, 1878, p. 289. 
