that too much pains
have been here bestowed upon a point which might be trusted to theory
to decide. I cannot think so. One of the most salient results of
these articles has been the proof of the fact that theory has been a
blind guide with regard to the velocity of the Polar rotation,
obscuring truth and misleading investigators for a half a century.
And even if we were certain, which we are not, that the fourteen
months' term is the Eulerian period in a modified form. It would
still be necessary to settle by observation the direction of the
annual motion, with regard to which theory is powerless to inform us.
To save repetition of argument, I must refer to the statement in _A.
J._, 273, pp. 68, 70, of the principles adopted in beginning these
inquiries in 1891."

Finally, he answers one of the few objectors of eminence who still
lingered, the great French physicist Cornu:--

[Sidenote: Cornu answered.]

"The ground is now cleared for examination of the only topic
remaining to be covered, to establish, upon the foundation of fact,
every point in the present theory of these remarkable movements of
the earth's axis. This is the question of the possibility that these
movements are not real, but merely misinterpretations of the observed
phenomena; being in whole or in part an illusory effect of
instrumental error due to the influence of temperature. Such a
possibility has been a nightmare in practical astronomy from the
first, frightening us in every series of unexplained residuals,
brought to light continually in nearly all attempts at delicate
instrumental research. A source of danger so subtile could not fail
to be ever present in the mind of every astronomer and physicist who
has given even a superficial attention to the question of the
latitude variations, and there is no doubt that some are even now
thus deterred from accepting these variations as proved facts.
Perhaps the most explicit and forcible statement of the doubts that
may arise on this subject has been given very recently by Mr. Cornu.
The views of so distinguished a physicist, and of others who are
inclined to agree with him, call for careful attention, and cannot be
neglected in the present closing argument upon the theory presented
in these articles. It is unnecessary, for the purpose