122 PHYSICAL GEOGRAPHY. 



intense, on account of the fierce winds. In the southern portion of the 

 state we have the trees and the birds, and we raise the grain and the 

 fruits common in the Northern states, while on the slopes of the moun- 

 tains and on the highlands in the vicinity of Connecticut lake, we 

 have the trees and the birds, and raise only the grain and the fruits of 

 the far north. 



Notwithstanding our extremes of temperature, we have a climate far 

 more healthful than that of most of the states east of the Rocky Moun- 

 tains. The extreme heat of summer is of so short a duration that it does 

 not produce the enervating effect of long continued heat, though of a 

 considerably lower temperature. The bracing air of winter, and the 

 charm of our autumn months, largely compensate for the few extremes 

 of summer and of winter. The lassitude produced by months of heat in 

 southern latitudes, and the extremes of cold, accompanied by fierce winds 

 that descend with such fell swoop in the west, are both unknown ; for 

 with us winds of great velocity, accompanied by intense cold, except on 

 the summits of our mountains, are extremely rare. 



Moisture of the Atmosphere. 



The climate of a country, as affecting vegetation, does not depend 

 altogether upon the absolute amount of rain-fall during the year ; but in 

 New Hampshire, particularly, the rain must be distributed through the 

 months when vegetation is growing, so that drouth will not check its 

 growth. Even when vegetation is growing, there must be other condi- 

 tions of moisture than rain-fall. The most important is the relative 

 humidity of the atmosphere. This is the relative amount of moisture in 

 the atmosphere, compared with that which it is capable of sustaining at 

 a given temperature. Saturation is assumed as ioo, and perfectly dry air 

 as o. The following is the absolute amount of moisture at the given 

 temperatures. 



Degrees F. Weight in grains Troy. 

 30 2.04 



50 4.08 



70 7.99 



80 IO.94 



Suppose the temperature is 30 , and the absolute amount of moisture 

 in the atmosphere is 2 grains, then there is half the amount present that 



