1Ft J5SIOW0. B5 



to east. The direction of the trade wind, how- 

 ever, is more apparent than real. 



The earth in its diurnal revolutions travels 

 at the rate of a little more than 1000 miles an 

 hour at the equator. But if we should travel 

 northward to within four miles, say, of the 

 north pole, the surface point would be mov- 

 ing at the rate of only about a mile an hour. 

 At some point equidistant between the north 

 pole and the equator the surface of the earth 

 will be moving at a rate, say, of 500 miles an 

 hour. If we could fire a projectile from this 

 point that would have a carrying power to take 

 it to the equator some time after the projectile 

 was fired, although it would fly in a perfectly 

 direct line, it would appear to anyone at the 

 equator who observed its approach to be mov- 

 ing from a northeasterly direction. The rea- 

 son is that the earth is traveling twice as fast 

 , at the equator as it is at the point whence the 

 projectile is fired. Therefore it will overshoot, 

 so to speak, at the equator, and not be dragged 

 around by the increased motion we find there. 



To make this still plainer, suppose the earth 

 to be standing still and a projectile be fired 

 directly across from the north pole in the di- 

 rection of the lines of longitude and required 

 one hour to reach the equator, the projectile 

 would appear to anyone standing at the 

 equator to come directly from the north. If, 

 however, the earth is revolving at the rate of 



