s, the entire
vegetation would soon have been devoured, and then the animals
themselves would of necessity have ceased to exist."

"How is it, then," inquired Willis, "with this continual
multiplication always going on, the inhabitants of land and sea do not
get over-crowded?"

"Why, as regards man, for example, if thirteen or fourteen human
beings are born within a given period, death removes ten or eleven
others; but though this leaves a regular increase, still the
population of the globe always continues about the same."

"It may be so, Master Jack, but when I was a little boy at school, I
generally came in for a whipping, if I made out two and two to be
anything else than four."

"And served you right too, Willis; but if the human family did not
continually increase, if the number of deaths exceeded continually
that of the births, at the end of a few centuries the world would be
unpeopled."

"Very good; but if, on the other hand, there is a continual increase,
how can the population continue the same?"

"Because the increase supposes a normal state; that is to say, the
births are only estimated as compared with deaths from disease or old
age. But then there are shipwrecks, inundations, plagues, and war,
which sometimes exterminate entire communities at one fell swoop. Then
whole nations die out and give place to the redundant populations of
others; phenomena now observed in the cases of the aborigines of
Australia and America."

"Very true."

"No signs of furs yet," cried Fritz, who was every now and then
levelling his rifle at the phantoms on shore.

"We need not dread," continued Jack, "ever being hustled or jostled on
the earth; life will fail us before space. There are now eight hundred
millions of human beings in existence, and, according to the most
moderate computation, room enough for twice that number. As it is, the
most fertile sections of the earth are not the most populous; there
are four hundred millions in Asia, sixty millions in Africa, forty in
America, two hundred and thirty in Europe, and only seventy millions
in the islands and continent of Oceanica!"

"To which," remarked Fritz, "you may add the eleven inhabitants of New
Switzerland."

"Assuming, then, this calculation to be nearly accurate, though
authorities vary materially in their computations of the earth's
inhabitants, and regarding it in connexion with the average duration
of human life, a thousand millions of mortals must