“In view of what I have said it is evident that the moon cannot be entirely airless. Recent observations have confirmed this conclusion, and some observers have thought that they could detect the presence of something resembling clouds occasionally creeping like low fogs over certain places on the moon. All this, you will observe, has an important bearing upon the question of life on the moon at the present day. Certain forms of plant life and low animal organizations might exist in such an atmosphere as the moon still possesses.” “But,” interjected my friend, “is not this that you have been telling me in contradiction to what you said about the cause of the sharp division between day and night on the moon, and about the visibility of the stars there in the daytime?” “Not at all,” I replied, “for the effects of which I spoke are relative. In any case the atmosphere of the moon must be too rare to diffuse any perceptible amount of light into the shadows, or to illuminate the sky sufficiently to render the stars invisible. The same reasoning applies to what I have told you about the contrasts of cold and heat on the moon. “But we have not yet finished with our photograph. We were looking at the plain of Plato, you will recollect. Notice, now, the _Mare Imbrium_ off the coast that adjoins Plato on the south. You see there several bright spots resembling islands. Islands they must have been if the _mare_ once had water covering it. One of these, standing by itself, an irregular, bright clump with a distinct shadow on the western side, bears the name of Pico, taken from the sharp peak in the Azores Islands. The broken mass southeast of Pico, and nearer the coast, constitutes the Teneriffe Mountains. You will notice that terrestrial geography has been drawn upon in this case also to supply a name. Still farther east is a long ‘island’ named the Straight Range. Beyond that, at the edge of the picture, appears Cape Laplace, at the western end of the ‘Bay of Rainbows.’