Still more recently, Luke Howard has summed up the labours of his life on this subject, and he writes:
"We have, I think, evidence of a great tidal wave, or swell in the atmosphere, caused by the moon's attraction, preceding her in her approach to us, and following slowly as she departs from these latitudes. Were the atmosphere a calm fluid ocean of air of uniform temperature, this tide would be manifested with as great regularity as those of the ocean of waters. But the currents uniformly kept up by the sun's varying influence effectually prevent this, and so complicate the problem.
"There is also manifest in the lunar influence a gradation of effects, which is here shown, as it is found to operate through a cycle of eighteen years. In these the mean weight of our atmosphere increases through the forepart of the period; and having kept for a year at the maximum it has attained, decreases again through the remaining years to a minimum; about which there seems to be a fluctuation, before the mean begins to rise again."—"On a Cycle of Eighteen Years in the Height of the Barometer" (Papers on Meteorology, Part II.; Phil. Trans., 1841, Part II.).
It is satisfactory to all interested in this matter to know that "the incontestable action of our satellite on atmospheric pressure, aqueous precipitations, and the dispersion of clouds, will be treated in the latter and purely telluric portion of the Cosmos" (vol. iii. p. 368., and note 596, where an interesting illustration is given of the effects of the radiation of heat from the moon in the upper strata of our atmosphere).
Jno. N. Radcliffe.
Dewsbury.
Not being quite satisfied with Mr. Ingleby's answer to W. W.'s Query, I beg to refer inquirers to the Nautical Magazine for July, 1850, and three subsequent months, in which will be found a translation by Commander L. G. Heath, R.N., of a paper published by M. Arago in the Annuaire du Bureau des Longitudes for the year 1833, entitled "Does the Moon exercise any appreciable Influence on our Atmosphere?" This treatise enters fully into the subject, and gives the results of several courses of experiments extending over many years; which go to prove that in Germany, at all events, there is more rain during the waxing than during the waning moon. Several popular errors are shown to have arisen in the belief that certain appearances in the moon, really the effect of peculiar states of the atmosphere, were the cause of such atmospheric peculiarities; but we are allowed some ground for supposing that this "vulgar error" may have some foundation in "vulgar truth."
G. William Skyring.
LATIN RIDDLE.
(Vol. viii., p. 243.)