132 ESSAY 



increase the quantity of moisture in the atmo- 

 sphere, must likewise tend to increase the pro- 

 duction of dew. Thus dew, in equally calm 

 and clear nights, is more abundant shortly after 

 rain, than during a long tract of dry weather. 

 It is more abundant, also, throughout Europe, 

 with perhaps a few exceptions, and in some 

 parts of Asia and Africa, during southerly and 

 westerly winds, than during those, which blow 

 from the north and the east. Aristotle* says, 

 that Pontus is the only country, in which dew 

 is more copious during a northerly, than during 

 a southerly wind. But a similar fact occurs in 

 Egypt ; for dew is scarcely ever observed there, 

 except while the Etesian winds prevail. Both 

 cases, however, though contrary to the letter, 

 are consonant with the spirit of the rule ; since 

 the north wind, in one country, proceeds from 

 the Euxine sea, and, in the other, from the Me- 

 diterranean. Another circumstance, of the same 

 kind with the blowing of wind from the south 

 and the west, as shewing that the air contains 

 much moisture, is the lessening of the weight of 

 the atmosphere. My experience on this point 

 has not, indeed, been great, as the falling of the 

 mercury in the barometer is very commonly 

 attended with wind or clouds, both unfavourable 



* Meteor. Lib. 1 . c. x. 



