THE PENDULUM DEMONSTRATION.
(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.
A. E. B.
Leeds.