1st. The cannon ought to be planted in a country situated between 0° and 28° of N. or S. lat. 2nd. It ought to be pointed directly toward the zenith of the place. 3rd. The projectile ought to be propelled with an initial velocity of 12,000 yards per second. 4th. It ought to be discharged at 10hrs. 46m. 40sec. of the 1st of December of the ensuing year. 5th. It will meet the moon four days after its discharge, precisely at midnight on the 4th of December, at the moment of its transit across the zenith. The members of the Gun Club ought, therefore, without delay, to commence the works necessary for such an experiment, and to be prepared to set to work at the moment determined upon; for, if they should suffer this 4th of December to go by, they will not find the moon again under the same conditions of perigee and of zenith until eighteen years and eleven days afterward. The staff of the Cambridge Observatory place themselves entirely at their disposal in respect of all questions of theoretical astronomy; and herewith add their congratulations to those of all the rest of America. For the Astronomical Staff, J. M. BELFAST, _Director of the Observatory of Cambridge._ CHAPTER V. THE ROMANCE OF THE MOON An observer endued with an infinite range of vision, and placed in that unknown center around which the entire world revolves, might have beheld myriads of atoms filling all space during the chaotic epoch of the universe. Little by little, as ages went on, a change took place; a general law of attraction manifested itself, to which the hitherto errant atoms became obedient: these atoms combined together chemically according to their affinities, formed themselves into molecules, and composed those nebulous masses with which the depths of the heavens are strewed. These masses became immediately endued with a rotary motion around their own central point. This center, formed of indefinite molecules, began to revolve around its own axis during its gradual condensation; then, following the immutable laws of mechanics, in proportion as its bulk diminished by condensation, its rotary motion became accelerated, and these two effects continuing, the result was the formation of one principal star, the center of the nebulous mass. By attentively watching, the observer would then have perceived the other molecules of the mass, following the example of this central star, become likewise condensed by gradually accelerated rotation, and gravitating round it in the shape of innumerable stars. Thus was formed the _Nebulæ_, of which astronomers have reckoned up nearly 5,000. Among these 5,000 nebulæ there is one which has received the name of the Milky Way, and which contains eighteen millions of stars, each of which has become the center of a solar world.