There have been many foolish myths about the moon: its ray has been considered poisonous to sleepers; the full moon has been regarded as a source of disease and madness, and has been supposed to affect the growth of plants, the medicinal properties of herbs, and the fortunes of human lives. The moon owes all these slanders to its nearness to us. In size the moon is about one-fourth the diameter of the earth, and its volume is but one-fiftieth that of our planet. The days and nights of the moon are not twelve hours long, but three hundred and sixty hours, equal, therefore, to fifteen of our twenty-four hour days. Only a little more than one side, or face, of the moon is ever seen by us. There have been many romantic fancies about what may be on the other side of the moon, but probably the side we do not see is very similar to the side which we do see. What is the past history of the moon? The first condition of any planet is that of burning vapor or gas, which must slowly cool and form a nucleus of solid or half-fluid matter. It is evident that the smaller the planet the more rapidly it will cool and become solid, and the greater the planet the longer it will remain in a partly fluid state. Thus Jupiter and Saturn will require much longer time to cool than Mercury or Venus. The sun, being by far the largest body in our system, will be gaseous or semi-fluid long after all the planets which he cast into space have cooled and hardened; while the moon, being one of the smallest planets, hardened long before the great planets, and before the earth. Thus the sun is still in the early stages of its existence, and the moon has run the course of its changes and is a burnt-out and aged world. No doubt the stages of moon-building were very like those of earth-building, with variations due to the much smaller size of the sphere. The nucleus would partially solidify, there would be a hardened crust which at intervals would crush in from the withdrawal of interior molten matter, or would be suddenly torn and flung up by the pressure of boiling lava from within. The condensing atmosphere no doubt sent down water upon the moon, but by long degrees the heated volcanic surface has parted with its seas, and we find the map of the moon now presenting us not with oceans, but empty sea-beds, volcano craters, and strange and arid depressions. The moon has no atmosphere; no rain falls on her barren surface; no clouds move above her; no tempests howl in her caverns; no snows crown her volcanic peaks; no sunsets shine in gorgeous colors; there are no violet and crimson skies at dawn. The moon is the kingdom of eternal calm, and sleep, and stillness. If any blow disturbs the lunar surface, it is from the fall of meteors rained upon it through space. It is to our atmosphere we owe the glories of the clouds, the beneficence of waters, the magic of frost changes, the rush of storms, the balmy breezes, the sky.