As to man, aëronautic experience teaches us that human life is endangered when the atmosphere is still sufficiently dense to support 12 inches of mercury in the barometer tube; what then would be his condition in a medium only sufficiently dense to sustain one-tenth of an inch of the barometric column? We have evidence from the most delicate tests that no atmosphere or vapour approaching even this degree of attenuation exists around the moon’s surface. Taking all these adverse conditions into consideration we are in every respect justified in concluding that there is no possibility of animal or vegetable life existing on the moon, and that our satellite must therefore be regarded as a barren world. * * * * * * * * After this disquisition upon lunar uninhabitability it may appear somewhat inconsistent for us to attempt a description of the scenery of the moon and some other effects that would be visible to a spectator, and of which he would be otherwise sensible, during a day and a night upon her surface. But we can offer the sufficient apology that an imaginary sojourn of one complete lunar day and night upon the moon affords an opportunity of marshalling before our readers some phenomena that are proper to be noticed in a work of this character, and that have necessarily been passed over in the series of chapters on consecutive and special points that have gone before. It may be urged that, in depicting the moon from such a standpoint as that now to be taken, we are describing scenes that never have been such in the literal sense of the word, since no eye has ever beheld them. Still we have this justification—that we are invoking the conception of things that actually exist; and that we are not, like some imaginary voyagers to the moon, indulging in mere flights of fancy. Although it is impossible for a habitant of this earth fully to realise existence upon the moon, it is yet possible, indeed almost inevitable, for a thoughtful telescopist—watching the moon night after night, observing the sun rise upon a lunar scene, and noting the course of effects that follow till it sets—it is almost inevitable, we say, for such an observer to identify himself so far with the object of his scrutiny, as sometimes to become in thought a lunar being. Seated in silence and in solitude at a powerful telescope, abstracted from terrestrial influences, and gazing upon the revealed details of some strikingly characteristic region of the moon, it requires but a small effort of the imagination to suppose one’s self actually upon the lunar globe, viewing some distant landscape thereupon; and under these circumstances there is an irresistible tendency in the mind to pass beyond the actually _visible_, and to fill in with what it knows must exist those accessory features and phenomena that are only hidden from us by distance and by our peculiar point of view. Where the material eye is baffled, the clairvoyance of reason and