nothing of the contents of the world upon which the immemorial generations of our ancestors have been evolved. Three times had I to repeat that of all the 4,000 miles of substance between the earth and its centre men knew only to the depth of a mile, and that very vaguely. I understood the Grand Lunar to ask why I had come to the moon seeing we had scarcely touched our own planet yet, but he did not trouble me at that time to proceed to an explanation, being too anxious to pursue the details of this mad inversion of all his ideas.
"He reverted to the question of weather, and I tried to describe the perpetually changing sky, and snow, and frost and hurricanes. 'But when the night comes,' he asked, 'is it not cold?'
"I told him it was colder than by day.
"'And does not your atmosphere freeze?'
"I told him not; that it was never cold enough for that, because our nights were so short.
"'Not even liquefy?'
"I was about to say 'No,' but then it occurred to me that one part at least of our atmosphere, the water vapour of it, does sometimes liquefy and form dew and sometimes freeze and form frost—a process perfectly analogous to the freezing of all the external atmosphere of the moon during its longer night. I made myself clear on this point, and from that the Grand Lunar went on to speak with me of sleep. For the need of sleep that comes so regularly every twenty-four hours to all things is part also of our earthly inheritance. On the moon they rest only at rare intervals and after exceptional exertions. Then
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