130 APPLICATION OF PRINCIPLES. 



It is to be remarked that the easterly winds are, in 

 this country, both the coldest and the driest. Mr. 

 Daniell tells us that the " moisture of the air flowing 

 from any point between n. e. and s. E. inclusive, is, 

 to that of the air from the other quarters of the com- 

 pass, in the proportion of *814 to "907, upon an ave- 

 rage of the whole year ;" and Mr. Thompson has 

 found the hygrometer to indicate not uncommonly 

 from 20° to 30° of dryness, during the long pre- 

 valence of the north-easterly winds in spring. At 

 the same time, the air is very cold, the effect of which 

 is to cause the sap- vessels of the stem to contract, and 

 refuse to convey their fluid ; so that the blossoms of 

 fruit trees in a north-east wind, while they are robbed 

 of their fluid contents by evaporation, can get no as- 

 sistance from the roots through the stem, and neces- 

 sarily perish. I find, however, from Mr. Thompson's 

 observations, that the greatest dryness we experience 

 in this climate is, not when the wind is in the east, 

 but when it is in the south. For example : in nine 

 years, between 1826 and 1834, the four driest days 

 were, in the year 1834, in June, when it was 33° on 

 the 1st, 35° on the 2d, and 31° on the 21st ; on the 

 1st of June, 1833, it was 30°, and always with a south 

 wind ; and, during the whole of those nine years, 

 there was but one other day on which the dryness 

 was found as high as 30°, namely on the 10th of April, 

 1834, with a north-east wind. The duration of dry- 

 when the gauge was upon or near the ground the annual average 

 was only 20-28 inches, or little more than half the amount evapo- 

 rated in a free and elevated exposure. 



