's result can be
reconciled with dynamic theory. I answer that it can, because the
theory which assigns 306 days as the time of revolution is based on
the hypothesis that the earth is an absolutely rigid body. But, as a
matter of fact, the fluidity of the ocean plays an important part in
the phenomenon, as does also the elasticity of the earth. The
combined effect of this fluidity and elasticity is that if the axis
of rotation is displaced by a certain amount, the axis of figure
will, by the changed action of the centrifugal force, be moved
toward coincidence with the new axis of rotation. The result is, that
the motion of the latter will be diminished in a corresponding ratio,
and thus the time of revolution will be lengthened. An exact
computation of the effect is not possible without a knowledge of the
earth's modulus of elasticity. But I think the result of
investigation will be that the rigidity derived from Mr. Chandler's
period is as great as that claimed by Sir William Thomson from the
phenomena of the tides."

[Sidenote: But Chandler's work still mistrusted.]

This was very satisfactory. Professor Newcomb put his finger on the
assumption which had been made so long ago that it had been forgotten: and
the lesson is well worth taking to heart, for it is not the first time
that mistaken confidence in a supposed fact has been traced to some
forgotten preliminary assumption: and we must be ever ready to cast our
eyes backward over all our assumptions, when some new fact seems to
challenge our conclusions. It might further be expected that this
discovery of the way in which theory had been defective would as a
secondary consequence inspire confidence in the other conclusions which
Mr. Chandler had arrived at in apparent contradiction to theory; or at
least suggest the suspension of judgment. But Professor Newcomb did not
feel that this was possible in respect of the _change_ of period, from
about twelve months in Bradley's time to fourteen months in ours. We have
seen that Mr. Chandler himself regarded this as a "curious result"
requiring confirmation: but since the confirmation was forthcoming, he
stated it with full confidence, and drew the following remarks from
Professor Newcomb in July 22, 1892:--

"The fact of a periodic variation of terrestrial latitudes, and the
general law of that variation, have been established beyo