32 W. Ferrel on motions of Fluids and Solids - 
only a comparatively small depression there, as represented in 
the figure, and instead of its being about 4, 000 feet lower at the 
equator than at the place of its maximum height near the trop- 
ics, there must be-only a very slight depression there, both on 
account of the small pressure from the equator, and ¢ Iso on ac- 
of the upward expansion arising from a greater tempera- 
“AL That the ene must assume the preceding figure in 
consequence of the eastward motion toward the poles and west- 
ward motion near ‘he eqmudtor: will be readily understood from the 
following illustration. It is well known that if the atmosphere 
had the same motion of rotation with the earth, that it would 
assume the same figure. Now, if the whole atmosphere had a 
greater angular motion, that is, if it had an eastward motion Te- 
lative to the earth, the increased centrifugal force would evi- 
dently cause it to accumulate at the equator and to be depressed 
at the poles. On the other hand, if it had a less angular mo- 
tion, that is, a motion westward "relative to the earth, it would 
ae The force which overcomes the resistance of the earth's 
surface to the east and the west motions of the atmosphere de- 
pends upon the term in equation (3) containing D, 4 as a -_ 
which depends upon the es nging motion of the flui 
tween the equatorial and the polar paar om hence the gin 
must val ‘ish at the ig ral 
motion of Se ee aphere is consequently ay by the re- 
there is a ahh ee of calms at the equator, called the equatorial calm 
belt, and there must be also a es of calms about the poles. 
18. As the motion of the a at ere is is east towards the poles 
r, Somewhere — the equator and 
io east or west, which 
and west motions of the aesetene tere earth’s ee = 
be such that the sum of the resistances of each part of the earth's 4 
multiplied into its distance from the axis of rotation, 
must be equal to 0, else the velocity of the earth’s rotation eo | j 
