and take for another example the farm of Antisana,
which is situated about midway up the Cordilleras, mountains of South
America. When travellers, arriving there from the summits which are
covered with perpetual snow, meet others arriving from the plain where
the heat is intense, those that descend are invariably bathed in
perspiration, whilst those that have come up are shivering with cold
and covered with furs. The reason of this is, that we cannot feel warm
till we have been cold, and _vice versa_."

"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," repl