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LUNAR CELESTIAL PHENOMENA.

centre of figure, or to the central point of the merespace occupied by the moon, but to the centre of themass, or the centre of gravity. There will be formedthere an ocean of more or less extent, according to thequantity of fluid directly over the heavier nucleus,while the lighter portion of the solid material willstand out as a continent on the opposite side....Inwhat regards its assumption of a definite level, airobeys precisely the same hydrostatical laws as water.The lunar atmosphere would rest upon the lunarocean, and form in its basin a lake of air, whose upperportions, at an altitude such as we are now con-templating, would be of excessive tenuity, especiallyshould the lunar provision of air be less abundantin proportion than our own. It by no means follows,then, from the absence of visible indications of wateror air on this side of the moon, that the other isequally destitute of them, and equally unfitted formaintaining animal or vegetable life. Some slightapproach to such a state of things actually obtains onthe earth itself. Nearly all the land is collected in oneof its hemispheres, and much the larger portion ofthe sea in the opposite. There is evidently an excessof heavy material vertically beneath the middle of thePacific; while not very remote from the point of theglobe diametrically opposite rises the great table-landof India and the Himalaya chain, on the summits ofwhich the air has not more than a third of the densityit has on the sea-level, and from which animatedexistence is for ever excluded.”