relative to the Earth's Surface. 39 
days, wh 
the general motions of the atmosphere may carry this disturbed 
area several thousands of miles. 
28. When the area of rarefaction is such as to cause the 
atmosphere to flow in below from all sides toward a centre and 
the reverse above, thus establishing a constantly interchanging 
motion between the internal and external part, the case becomes 
very similar to that of the general hemispherical motions of the 
atmosphere in which the motion is between the polar and equa- 
torial parts. For if the earth’s rotation on its axis is analyzed 
with reference to any other axis, the pole of which is at the dis- 
tance of 6 from the pole of the earth, it is found to have a rotation 
around this latter axis equal to n cos 6 (Peirce’s Analytical Me- 
chanics, § 25). ence the interchanging motion between the 
internal and external part in this case must cause the internal 
gate to gyrate around the centre from right to left in the northern 
emisphere, and the external part the contrary way, and thus 
give rise to a cyclone or revolying storm just as in the case of the 
hemispherical motions the part nearest the pole acquires an east- 
