Of all the links in the stupendous chain of the cosmos, the sun, next to our own planet, is that which we are most concerned in knowing well, while it is precisely that which we know the least. This glorious orb has always been involved in the deepest mystery. All that had been revealed to us concerning it, till very recently, was derived from the observations and deductions of the elder Herschel. His discovery of a double luminous envelopment, at times partially withdrawn from various portions of the sun’s surface, afforded, on the whole, a satisfactory explanation of the numerous spots that are always seen on his disk. This glimpse merely of the external changes which happen on his surface made up the sum of our knowledge of that great luminary on which the animation of our planetary system depends! One main cause of this utter ignorance on the subject, besides its own intrinsic difficulty, lay in the comparatively slight attention it had always received from astronomers generally. No individual observer ever thought of devoting himself to the solar phenomena alone, while the public observatories confined themselves to merely observing the sun’s culmination at noon, or to ascertaining the exact duration of its eclipses. We knew, from the observations of Cassini and Herschel, that the spots on the sun’s disk are not alike numerous every year; and Kunowsky particularly drew the attention of astronomers to the fact, that while in the years 1818 and 1819 very large and numerous ones appeared, some visible even to the naked eye, very few, on the contrary, and those of but trifling size, were seen in the years 1822-1824. But it was reserved for the indefatigable Schwabe of Dessau, who has devoted himself for a long series of years to this one single object, to establish the fact of these spots observing a certain periodicity. Among the results of his labors—for as yet we have only his brief announcements to the scientific world in the “Astronomical Notices”—are the following: 1. That the recurrence of the solar spots has a period of about ten years; 2. That the number of the single groups of one year varies at the minimum time from twenty-five to thirty, while in the maximum years they sometimes rise to above three hundred; 3. That with their greater abundance is combined also a greater local extension and blackness of the spots; 4. That at the maximum time, the sun, for some years together, is never seen without very considerable spots. The last maximum appears to have been of a peculiarly rich character, as, from February, 1837, till December, 1840, solar spots were visible on every day of observation; while the number of groups in the former of those years amounted to 333.