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surface. It can be easily seen about the time of the new moon with a telescope of moderate size.

One of the most important questions connected with the moon is whether there is any air or water on its surface. To these the answer of science up to the present time is in the negative. Of course this does not mean that there can absolutely not be a drop of moisture nor the smallest trace of an atmosphere on our satellite; all we can say is that if any atmosphere surrounds the moon it is so rare that we have never been able to get any evidence of its existence. If the latter had such an appendage of even one hundredth of the density of the earth's atmosphere, its existence would be made known to us by refraction of the light from a star seen alongside the moon. But not the slightest trace of any such refraction can be discovered. If there is any such liquid as water, it must be concealed in invisible crevices, or diffused fused through the interior. Were there any large sheets of water in the equatorial regions they would reflect the light of the sun day by day, and would thus become clearly visible. The water would also evaporate and form more or less of an atmosphere of watery vapour.

All this seems to settle another important question; namely, that of the habitability of the moon. Life, in the form in which it exists on our earth, requires water at least for its support, and in all its higher forms air also. We can hardly conceive of a living thing made of mere sand or other dry matter such as forms the lunar