do with the vortex that produced it; it travels in the
general direction of the local atmosphere of the place--in intratropical
latitudes westward, in extratropical latitudes eastward. If, therefore,
the disturbance forms at the place of observation, there will probably
be no storm; but further eastward its action would be more apparent or
violent. It is impossible, of course, to lay down any general
description which shall meet every case. It is a knowledge that can only
be acquired by observation, and then is not readily or easily
communicated. There are many contingencies to be allowed for, and many
modifying causes to keep sight of, to enter into which would only be
tedious; we shall, therefore, confine ourselves to the prominent
phenomena.

ACTION OF THE POLAR CURRENT.

We have seen how the passage of the axis of the vortex may derange the
electric tension of the parts passed over; but there is another mode of
action not yet adverted to.

[Illustration: Fig. 1]

When the moon is at her perigee, the axis of the vortex passes through
the centre of gravity of the earth and moon at C, and cuts off the
segment RR. At the apogee, on account of her greater distance, and of
her consequent power to _push_ the earth out from the axis of the vortex
XX, the segment R'R' is only cut off by the axis; and the angle which
the axis makes with the surface will vary with the arcs AR and A'R'; for
these arcs will measure the inclination from the nature of the circle.
In passing from the perigee to the apogee the axis will pass over the
latitudes intermediate between R and R' in both hemispheres, neither
reaching to the equator E, nor to the pole P. Let us now suppose a
meridian of the earth, represented by the line NRS, N being north, and S
south, and the surface of the atmosphere by N'S'; XX still representing
the axis of the vortex, ordinarily inclined 34d or 35d to the surface.
Let us also conceive the rotation of the earth to cease, (the action of
the vortex remaining the same,) thus leaving the axis over a particular
longitude. If the ether possesses inertia, there will be an actual
scooping out of the upper portions, driving them southward to a certain
distance, where the atmosphere will be piled up above the ordinary
level. There will, therefore, be a strong contrary current at the
surface of the earth to restore the equilibrium, and if the action be
violent, the surface wind will be increased; so that if it be considere