BAROMETER. 327 



was checked by the cold) is carried on 

 very rapidly, in consequence of the 

 diminished pressure of the air. 



(N. B. The less the pressure of the air, the more 

 rapidly it evaporates moisture.) 



Q. When does the barometer VARY MOST ? 

 A. In winter time. 



Q. Why does the barometer vary MORE in 

 WINTER than in SUMMER time ? 



A. Because the difference of tempe- 

 rature between the torrid and temperate 

 zones is so great, that the state of the air 

 is perpetually disturbed by their mixing 

 together. 



Q. When does the barometer YARY LEAST ? 



A. In summer time. 



Q. Why does the barometer vary LESS in 

 SUMMER than in WINTER time ? 



A. Because the temperature of our 

 island is so nearly equal to that of the 

 torrid zone, that its state is not much 

 disturbed by interchange of currents. 



Q. What effect has WIND on the barometer ? 



A. NORTH and EAST winds make the 

 mercury rise; all other winds make it 

 sink; but SOUTH and WEST winds make 

 it sink lower than any other winds. 



