73 
1918-19.] The Origin of Anticyclones and Depressions. 
towards the high pressure). Yet when the wind has moved half-way to 
the centre, one-fifth of its energy is still derivable from the earth’s rotation. 
A portion of the energy is consumed in overcoming frictional resistance, 
and hence when the air finally reaches the region of cooling and is itself 
expelled towards the high-pressure regions by reason of its increased 
volume-inertia ( i.e . density), it will not long maintain its cyclonic circula- 
tion but will soon commence to circulate anticyclonically by reason of its 
outward motion, in spite of the fact that it is moving around a low-pressure 
area (see fig. 8, which shows the circulation at different levels in a well- 
