[Letters to Editor]


IN Dr. William Lockyer's review of Dr. Russel Wallace's book on the habitability of Mars he refers to Dr. Johnstone Stoney's contention that aqueous vapour cannot exist on a planet of that size because the velocity of the molecules would be too great for its attraction to retain them. I do not know what temperature was assumed in the calculation, but a dozen miles above the surface of the planet the temperature of its atmosphere must approach absolute zero—a condition of things in which even hydrogen would not have the necessary velocity to escape.

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EVANS, J. [Letters to Editor] . Nature 77, 392 (1908). https://doi.org/10.1038/077392c0

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