3. The origin of the general and particular phenomena of the sun-spots. 4. The cause of the varying splendor of the photosphere, including such details as the “faculæ,” “mottling,” “granulations,” etc., etc. 5. The forces which upheave the solar prominences. 6. The origin of the corona and zodiacal light. 7. The origin of the meteorites and the asteroids. 8. The meteorological phenomena of the planets. 9. The origin of the rings of Saturn. 10. The origin of the special structure of the nebulæ. 11. The source of terrestrial magnetism, and its connection with solar activity. The first and second chapters are devoted to an examination of the limits of atmospheric expansibility. The experimental investigations of Dr. Andrews, Mr. Grove, Mr. Gassiot, and M. Geissler are cited to prove that the expansibility of the atmosphere is unlimited, and other cosmical evidence is adduced in support of this conclusion. As this, which is really the foundation of the whole argument, is directly opposed to the views expressed by Dr. Wollaston, in his celebrated paper on “The Finite Extent of the Atmosphere,” published in 1822, and generally accepted as established science, this paper is reprinted in the second chapter, and carefully examined. Dr. Wollaston says “that air has been rarefied so as to sustain 1-100th of an inch of barometrical pressure,” and further, that “beyond this limit we are left to conjectures founded on the supposed divisibility of matter; if this be infinite, so also must be the extent of our atmosphere.” I contend that our knowledge of the whole subject is fundamentally altered since these words were written. We are no longer “left to conjectures founded on the supposed divisibility of matter” to determine the possibility of further expansibility than that indicated by 1-100th of an inch of barometrical pressure, as we now have means of obtaining ten times, a hundred times, a thousand times, or even an infinitely greater rarefaction than Wollaston’s supposed limit, an apparently absolute vacuum being now obtainable; and although the transmission of electricity affords a means of testing the existence of atmospheric matter with a degree of delicacy of which Wollaston had no conception, we are still unable to detect any indication of any limit to its expansibility.