PHILOSOPHY OF THE TRADE WINDS. 317 



perpetually blow directly from the poles to the 

 equator; but in consequence of its revolution, 

 the direction of the current is bent aside, and 

 the wind becomes an easterly wind with a direc- 

 tion from the north, or from the south in south 

 latitude, instead of a strictly north or south 

 wind. Since the earth revolves from west to 

 east, a current of air having a less velocity than 

 the surface over which it was being drawn, 

 would be felt by one standing on the earth as a 

 wind from the east. As we approach the equa- 

 tor its northerly direction gradually ceases, and 

 it is felt as an east wind, and thus forms the 

 more proper trade wind, a current blowing from 

 east to west within the tropics. Thus the high 

 temperature of the equator sets in motion, and 

 the revolution of the globe modifies, the direc- 

 tion of the trade winds. 



The effect of the earth's motion in producing 

 what is felt to be a wind, by its brushing 

 against a body of slowly moving air, may be 

 rendered somewhat more intelligible by refer- 

 ence to an every-day illustration. The outside 

 traveller on a railroad carriage, going at the 

 rate of thirty or forty miles the hour, expe- 

 riences apparently a very powerful current of 

 air blowing in his face, so long as the machine 

 continues in motion. Yet he may notice the 

 distant smoke curling up from the cottage 



