164 THE WEATHER, AND WEATHER PROPHETS. 



in our ordinary barometers. When the North-east wind 

 brings snow, as it very frequently does, it is not by the 

 precipitation of its own moisture ; but by its intrusion as a 

 cold wind into a warmer atmosphere charged with mois- 

 ture, and ready to deposit it under any cooling influence. 



(27.) Complementary to the phenomenon just men- 

 tioned of a tendency to North-easterly wind in the 

 spring, i.e., to the production of a lull or temporary 

 intermittence in the regular South-west current, and the 

 substitution for it of its opposite ; may be considered that 

 aggravation of its intensity which takes place subsequent 

 to the autumnal equinox ; exaggerated, however, and 

 thrown later into the season, viz., into November, by the 

 conspiring action of several distinct causes, which we 

 will now proceed to explain. 



(28.) As the sun in its annual course traverses the 

 northern and southern halves of the ecliptic, it creates 

 summer in the one hemisphere, simultaneously with 

 winter in the other ; and the balance of aerial expansion 

 and aqueous evaporation is alternately struck in favour 

 of each. As a necessary consequence, a large amount 

 both of air and of aqueous vapour carrying air along 

 with it, is alternately driven over from one hemispheie 

 to the other. The only course which the elements so 

 transferred can pursue, is by passing in the higher 

 regions of the atmosphere across that medial line where 

 the two superior out-flowing currents separate on their 

 courses towards either pole in other words, by joining 

 with, and reinforcing the " anti-trade" current on that 

 bide of the equator towards which they are propelled 



