“Our bodies,” resumed Fritz, “however much the thermometer descends, never mark less than thirty-five degrees above zero.  In winter the skin shrinks, and becomes a bad conductor of heat from without; but, at the same time, does not allow so much gas and vapor to escape from within.  In summer, on the contrary, the skin dilates and allows perspiration to form, a process that consumes a considerable amount of latent heat.  Starting from this principle, it has been calculated that a man, breathing twenty times in a minute, generates as much heat in twenty-four hours as would boil a bucket of water taken at zero.”

“If means could be found,” remarked Jack, “to furnish him with a boiler, by fixing a piston here and a pipe there man might be converted into one of the machines we were talking about the other day.”

“Were I disposed to philosophize,” added Fritz, “I might prove to you that for a long time men have been little else than mere machines.”

Before night they had run about thirty miles further to the north-east, without seeing any thing beyond a formidable bluff, guarded by a fringe of breakers, that would soon have swallowed up the Mary had she ventured to reach the land.  It was necessary however to obtain fresh water at any price before they resumed their voyage.

It was to be feared that all the islanders of the Pacific were not in expectation of a great Rono, consequently Willis suggested that it would be as well to search for an uninhabited spot.  The only question was, how long they might have to search before they succeeded; for they knew that there were plenty of small islands in these latitudes unencumbered by savages, and furnished with pools and springs of water.

Night at length closed in upon them, and with it came a dense mist, that enveloped the Mary as if in a triple veil of muslin.

“Willis,” inquired Jack, “what difference is there between a mist and a cloud?”

“None that I know of,” replied the Pilot, “except that a cloud which we are in is mist, and mist that we are not in is a cloud.  And now, my lads,” he added, “you may turn in, for I intend to take the first watch.”

Before turning in, however, all three joined in a short prayer.  The young men had not yet forgotten the pious precepts of their father.  Prayer is beautiful everywhere, but nowhere is it so beautiful as on the open sea, with infinity above and an abyss beneath.  Then, when all is silent save the roar of the waves and the howling of the winds, it is sublime to hear the humble voice of the sailor murmuring, “Star of the night, pray for us!”

That night the star of the night did pray for the three voyagers, for the rays of the moon burst through the darkness and the mist, and fell upon a long line of reefs under the lee of the pinnace.  Had they held on their course a few minutes longer, our story would have been ended.

CHAPTER XXI.