(Vol. v., p. 84.)
A few lines will suffice for my rejoinder to H. C. K.'s further
observations on this subject.
Since he and I are substantially of the same opinion as to the reality
of the phenomenon, it would be bootless to discuss the comparative
merits of the considerations that have led us to it. But inasmuch as I
am very careful in making assertions, so am I proportionately impatient
when their correctness is wrongfully impugned.
H. C. K., in remarking upon a statement of mine, enters into a
calculation to show that it is absurd. At least such I suppose to be the
meaning of the paragraph concluding with the words "which is absurd."
My assertion was, that the difference alluded to was "greatly in excess
of the alleged apparent motion."
Now "_the difference_" was fifty feet in twenty-four hours, or upwards
of two feet in the hour; and "_the alleged apparent motion_" had been
stated over and over again to be a complete revolution in about thirty
hours (for the latitude of London). Hence, the circumference of a
ten-feet circle being about thirty feet, it requires no great profundity
to discover that "the alleged apparent motion" is one foot in the hour;
but the "difference" in velocity is two feet in the hour, which surely
justifies the assertion that the latter is "greatly in excess" of the
former.
It would occupy too much space to show H. C. K. where it is that his
calculation has gone astray; but if he will reconsider it, he will
perceive, firstly, that he has no authority, except his own, for
assuming a revolution (of the line of oscillation) in _twenty-four_
hours; and secondly, that five feet _on either side_ of the centre is
equal to ten feet altogether.
But, above all, he must recollect that his own original assertion (Vol.
iv., p. 236.), to which mine was but an answer, was, that "the
difference" would be "_practically nothing_:" of this even his own
calculation is a sufficient refutation.