Note IV, p. 58.—On the means by which it may probably be ascertained whether the Moon be a habitable world

About the year 1818, the Author published in the Monthly Magazine, a few observations on the surface of the Moon, in which a few remarks were offered on this subject. The following is an extract from that communication:—

“If we be ever to obtain an ocular demonstration of the habitability of any of the celestial orbs, the Moon is the only one where we can expect to trace, by our telescopes, indications of the agency of sentient or intelligent beings; and I am pretty much convinced, that a long-continued series of observations on this planet, by a number of individuals in different places, might completely set at rest the question, ‘Whether the Moon be a habitable world.’ Were a vast number of persons, in different parts of the world, to devote themselves to a particular survey of the Moon—were different portions of her surface allotted to different individuals, as the object of their particular research—were every mountain, hill, cavern, cliff, and plain, accurately inspected—and every change and modification in the appearance of particular spots carefully marked and represented in a series of delineations, it might lead to some certain conclusions, both as to her physical constitution, and her ultimate destination. It can be demonstrated, that a telescope which magnifies 100 times, will show a spot on the Moon's page 151 surface, whose diameter is 1223 yards; and one which magnifies 1000 times, will, of course, enable us to perceive a portion of her surface, whose size is only 122 yards; and, consequently, an object, whether natural or artificial, of no greater extent than one of our large edifices (such as St. Paul's cathedral, London), may, by such an instrument, be easily distinguished. Now, if every minute point on the lunar surface were accurately marked by numerous observers, it might be ascertained whether any changes are taking place, either from physical causes, or from the operations of intelligent agents. If a large forest were cutting down—if a city were building in an open plain, or extending its former boundaries—if a barren waste were changing into a scene of vegetation—or, if an immense concourse of animated beings were occasionally assembled on a particular spot, or shifting from one place to another—such changes would be indicated by certain modifications of shade, color, or motion; and, consequently, would furnish a direct proof of the agency of intelligent beings analogous to man, and of the Moon being a habitable globe. For although we may never be able to distinguish the inhabitants of the Moon (if any exist), yet if we can trace those effects which can flow only from the operations of intelligent agents, it would form a complete demonstration of their existence, on the same ground on which a Navigator concludes an unknown island to be inhabited, when he perceives human habitations and cultivated fields.

“That changes occasionally happen on the lunar hemisphere, next the earth, appears from the observations of Herschel and Schroeter, particularly from those of the latter. In the Transactions of the Society of Natural Philosophy at Berlin, Schroeter relates, that, on the 30th December, 1791, at five o'clock, p. m., with a seven feet reflector, magnifying 161 times, he perceived the commencement of a small crater on the southwest declivity of the volcanic mountain in the Mare Crisium, having a shadow of at least 2”-5. On the 11th January, at twenty minutes past five, on looking at this place again, he could see neither the new crater, nor its shadow. Again, on the 4th January, 1792, he perceived, in the eastern crater of Helicon, a central mountain, of a clear gray color, 3″ in diameter, of which, during many years’ observations, he had perceived no trace. ‘This appearance,’ he adds, ‘is remarkable, as probably from the time of Hevelius, the western part of Helicon has been forming into its present shape, and Nature seems, in that district, to be particularly active.’—In making such minute observations as those to which I allude, it would be proper, along with an inspection of the Moon's luminous disc, to mark the appearances of different portions of her dark hemisphere, when it is partially enlightened by the reflected light from the earth, soon after the appearance of new moon. These researches would require a long-continued series of the most minute observations, by numerous observers in different regions of the globe, which could be effected only by exciting, among the bulk of mankind, a general attention to such investigations. But were this object accomplished, and were numerous observations made from the tops of mountains, and in the serene sky of southern climes, where the powers of the telescope are not counteracted by dense vapors, there can be little doubt that direct proofs would be obtained, that the Moon is a habitable world; or, at least, that the question in relation to this point would be completely set at rest.”