Page:Popular Science Monthly Volume 50.djvu/859

Rh, on the November meteors, and describing minutely the successive phenomena of the earthquake of March 17, 1871. A communication in the second volume sets forth a method of magnetic surveys of limited districts in which investigators might employ themselves during their vacations, and which he had practiced satisfactorily during two successive vacations. These were probably the survey of the west of France, made in 1868 in company with Father Sidgreaves, and that of the east of France, made in 1869. A detailed account of such a survey made by him in Belgium one autumnal season was communicated to the Royal Society, with the magnetic elements of twenty stations and the secular variation. Other studies on this subject are recorded; one comparing the curves as shown by the photographs in terrestrial magnetism at Stonyhurst and Vienna, which was spoken of as remarkable in that the curves offered a striking illustration of the simultaneous action of the disturbing forces of two magnets many miles apart; and observations by him and Prof. Balfour Stewart on the regular fluctuations of declination at Stonyhurst and Kew, of which the authors remarked that "such fluctuations almost always occur as couplets or groups of couplets—a couplet meaning first a descent and then an ascent, or the reverse"; and the paper offered an explanation of the phenomena. A communication on the magnetic storm of October, 1872, calls attention to the importance of observations of such manifestations, in view of the coincidences discovered between them and other important natural phenomena.

In an address delivered in 1872 or 1873 to the Liverpool Polytechnic Society, after explaining what was known of terrestrial magnetism and remarking upon the observed coincidence of magnetic disturbances with the passing of earth currents, "their never-failing appearance at all auroral displays, their simultaneous appearance at places the most remote from each other, and their agreement in various periodic features with outbursts of sun spots," were spoken of as most powerful aids to the solution of the problems connected with them; and he suggested that it was not unreasonable "to expect that some light may be thrown upon the question, if we examine with careful attention the not impossible connection of magnetic storms with solar outbreaks, or with volcanic eruptions and violent earthquakes, with the variations of the wind, or even with the showers of fallen meteors." Further, he asked, if the connection supposed by certain students between the period of solar spots and the relative position of the planets can be maintained, "if the solar disturbances are in any way due to the combined action of the planets, and these again are found to be coincident with the great perturbations of terrestrial magnetism, shall we not be inclined to attribute a wider range to the