LUNAR CELESTIAL PHENOMENA.

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air is still one-fourth as dense as at the sea-level. Sothat, even though the lunarians had so large a quantityof air as I have supposed, they must still be constitutedvery differently from men, since men would perish atonce if placed in an atmosphere so attenuated.

But there is a more important point to be consi-dered. We see that an atmosphere of a given quan-tity per square mile of lunar surface would reach muchhigher than a similar atmosphere on the earth. Onehalf of it would lie above a height of 22 miles, that is,enormously above the summits of the highest lunarmountains. Far the greater portion of the atmospherewould ile above the lunar high lands. Supposing theatmosphere differently constituted, and of specificgravity six times as great as our air under the same

nero, and the neck of the balloon was covered with hoar frost.”—(From my article on the balloon in Rodwell’s “ Science Dictionary.”)“ It is worth noticing, however,” I proceed, “that although it wouldseem from this experience that no man accustomed to breathe theair at ordinary levels, can hope to attain a greater height than 6|miles, it is not impossible that those who pass their lives at a greatheight, as the inhabitants of Potosi, Bogota , and Quito , mightsafely ascend to a far greater height. We know that De Saussure was unable to consult his instruments when he was at no higherlevel than these towns, and that even his guides fainted in tryingto dig a small hole in the snow ; whereas the inhabitants of thetowns thus exceptionally placed, are able to undergo violent exer-cise. We may assume, therefore, that their powers are exception-ally suited to such voyages as those in which Glaisher and Coxwellso nearly lost their lives.” Nevertheless it may be regarded ascertain that no race of men could exist even for a few minutes inan atmosphere having a specific gravity less than one-sixth that ofour own air.