J 4 GENKRAL INPRODUC TION. 



uYj^ January, February, and March. Notwithstandino- tlicse facts, 

 diseases of die lungs are rare among the inhal)itants, and even the 

 severe winters liave prov(id of l)enefit to those consumptives that have 

 remained here throughout the entire year. 



The mean annual rain-fall exceeds that of most jiortions of the 

 State, and is estimated by Mr. Colvin, from the available data, to be 

 45. 1 8 inches (i , 149 mm.) for the entire region. The mean annual rain- 

 f^dl over the whole State is 41.94 inches (1,063 mm.).''' 



There are two elements that tend to increase the humidity of this 

 region : ist. its mountainous characttM", for mountains alwa)-s act as 

 condensers of moisture; and 2d, its heav)- covering of forests, for 

 dense vegetation protects die 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 Huid to a gaseous condition, is a cooling 

 process, antl die air near the surface, being scr(;ened from the sun and 

 from the winds, becomes b)- this mcians so humid, that a rank suc- 

 culent veg(;tation oftcMi si)rings up and thri\('s, which in an oj)en field 

 would wither and perish in an li()ur."-j- 



Now it is well known that there is, in nature, no such thing as a 

 perfecdy dr)- atmosphere, for at all times, and in all i)laces, it is laden 

 with less or more aqueous va[)or in a state of suspension. The higher 

 the temperature the greater the capacity for carr}'ing moisture, and 

 consec^uendy the more moisture recjuired to produce saturation — by 

 which term we understand the maximum ([uaiitit)' of watery vapor 

 that a definite amount of atniosi)heric air can contain at any given de- 

 gree of tcMiiperature. No evaporation whatever can take place from any 

 surface in a saturated atmosphere, and any cooling of such an atmos- 



* Meteorology of New Vork Stale, Second Series, 1<". 15. Hough, 1872, p. ix. 

 \ Hough's Report on Forestry, 187S, p. 2S9. 



