110 
HAROLD’S DISCUSSIONS. 
We would naturally tliink that the air would flow 
toward the equator all the way from the poles, and 
give us north winds in the northern hemisphere 
and south winds in the southern hemisphere. This 
would tend to draw the air away from the poles, pro¬ 
ducing low barometer, thus leaving a partial vacuum 
into which the higher air would drop, so that a current 
toward the poles would be started in the upper air. 
Then the circulation would be as follows: the warm 
air at the equator would rise and flow toward the 
poles, descend to the surface of the earth, and as a 
north or a south wind flow off toward the equator. 
Thus there would be polar winds all over the surface 
of the earth except at the equator, where it would be 
calm. Probably this would be the case if the earth 
were a globe of some uniform substance like glass, or 
were everywhere covered with water and did not ro¬ 
tate on its axis. But this ideal circulation exists only 
in part, and we must therefore look for influences 
which disturb the direction of the air currents. 
HOW THE WINDS BLOW. 
Observations covering a considerable period of 
time have been made in many parts of the world, 
and their results recorded. We can notice only a 
few of them, but enough to form some idea of the 
movements of the air, and to interest you, reader, in 
making some observation for yourself. 
We will begin at the equator. Here, and on both 
sides of it, the records show that there is little wind, 
especially out at sea. It is the great region of calms. 
