ates, particularly in the great plains of the west, the
weather can be better compared; not only on account of the latitude
being more favorable, but also on account of the greater magnetic
intensity of the western hemisphere.

It must also be remembered that there are in latitude 40d, five or six
distinct passages of the disturbing cause in one sidereal period of the
moon. If two of these periods are drawn closer together by the change of
the elements, the interval between two others must necessarily be
increased. Besides, the effect produced is not always the same, for
reasons already adverted to. One vortex may be more violent one month,
or for a few days in one month, while another may be more active the
next. It may also happen that for several successive passages, the
passage shall be central in one latitude, while two or three degrees
north or south, another place shall be passed by. In different months
and in different years, as well as in different seasons of the year, the
energy of the ether may be augmented or diminished. But it may be said,
that, supposing the theory true, if its indications are so uncertain, it
is of little value. By no means. It is true there are many things to be
inquired into; but it is a great thing in this science to be able to
take the first step in the right direction,--to find even the _key_ of
the portal. It is a great stride to be able to say, a storm may happen
at such a time, but cannot happen at another; that a storm, when raging,
will go in this direction, rather than in that; that it will be central
here, and less violent yonder; and when we consider its bearing on
astronomical and other science, it is difficult to exaggerate its value
to the world at large.

Again, it may be said that rain, and cloudy days, and fresh breezes, and
even strong winds, sometimes occur, when the vortices do not pass
centrally. This is true; yet only indicating that where the vortices are
central, an unusual disturbance is taking place. But there is another
cause, which was purposely omitted in considering the prominent features
of the theory, in order not to encumber the question with secondary
influences. By referring to Fig. 3, section 1, we see that the lateral
vortices of the globe are continually passing off to the southward, in
the northern hemisphere, in a succession of dimples, and continually
reforming. We will now represent this mode of action in profile, as it
actually occurs in the i