prepared to find that breakages would be more numerous
during the times of vigorous oscillation; and it seems probable that in a
similar way the little cracks of the earth's skin which we call great
earthquakes are more numerous when these unbalanced vibrations are at
their maximum; that is to say, about once every seven years. This result
is scarcely yet worthy of complete confidence, for our observations of
earthquakes have only very recently been reduced to proper order; but if
it should turn out to be true, it is scarcely necessary to add any words
of mine to demonstrate the importance of this rather unexpected result of
the Latitude Variation.

[Sidenote: The Kimura phenomenon.]

Finally I will mention another phenomenon which seems to be at present
more of a curiosity than anything else, but which may lead to some future
great discovery. It is the outcome of observations which have been
recently made to watch these motions of the Pole; for although there seems
good reason to accept Mr. Chandler's laws of variation as accurate, it is
necessary to establish their accuracy and complete the details by making
observations for some time yet to come; and there could be no better proof
of this necessity than the discovery recently made by Mr. Kimura, one of
those engaged in this watch of the Pole in Japan. Perhaps I can give the
best idea of it by mentioning one possible explanation, which, however, I
must caution you may not be by any means the right one. We are accustomed
to think of this great earth as being sufficiently constant in shape; if
asked, for instance, whether its centre of gravity remains constantly in
the same place inside it, we should almost certainly answer in the
affirmative, just as only twenty years ago we thought that the North Pole
remained in the same place. But it seems possible that the centre of
gravity moves a few feet backwards and forwards each year--this would at
any rate explain certain curious features in the observations to which Mr.
Kimura has drawn attention. Whatever the explanation of them may be, or to
settle whether this explanation is correct, we want more observations,
especially observations in the Southern Hemisphere; and it is a project
under consideration by astronomers at the present moment whether three
stations can be established in the Southern Hemisphere for the further
observation of this curious phenomenon. The question resolves itself
chiefly into a question of money