The most important result connected with modern researches on the solar sputa is due to Schwabe, a German astronomer, who, by per severingly observing the sun on every day that he was visible between the years 1S26 and ISLE, finally discovered that the number visible on the disc in the course of a year is subject to a periodic variation, passing through the cyclo of its values in successive intervals of about eleven years. Shortly afterwards M. Lamont, Director of the obser vatory at Munich, discovered that the diurnal variation of magnetic needle is subject to a corresponding period of equal duration. The researches of Schwabe have been confirmed by Mr. Carrington and other recent observers of the solar spots. Professor Wolf of Zurich, having carefully compared all the recorded observations of the spots, has also discovered unequivocal evidence of the existence of a law in the frequency of their appearance on the solar disc. The duration of the perish, as might be expected from the imperfect nature of the ebservations, is found by Professor Wolf to be subject to considerable irregularities, but on the whole, the observations plainly indicate a recurrence in successive cycles of nearly the same number of spots visible on the disc in the course of a year. The following table, con structed by Professor Wolf from the recorded observations of the spots, exhibits the relative number of spots visible during each of the I sit 112 years :— A telescope of six inches aperture has been recently fitted up by the Royal Society, at the Kew Observatory, under the superintendence of Mr. De la Rime, for the purpose of taking daily photographic delineations
of the sun's surface. The experiment has been attended with complete success, and important results may be expected from the comparison of a series of such records.
The origin of the heat and light of the sun is one of the most obscure points of astronomy. The most recent speculations on the subject arc due to Profersan• William Thomson of Glasgow, who supposes a zone of meteors to circulate around the sun, within the orbit of Mercury, and to he falling gradually upon his surface in consequence of the resistance offered to them by the solar atmosphere. According to this theory, the solar light and heat are generated by the mechanical impact of the meteors on the sun's surface. The existence of a solar atmosphere may be considered to be eatablished beyond all doubt by the corona seen during total eclipses of the sun, and by the fact, that the red pro minences seen on such occasions have been observed in several instances to bo isolated from the moon's limb. That these prominences aro solar and not lunar phenomena has been satisfactorily proved by the numerous observations of the total eclipse of 1860, and more especially by the admirable photographs of the phenomenon taken by Mr. De la hue with the Kew photo-heliograph at Miranda del Ebro. (Swam Ecsiese.]