"You are right, my friend, but we need not fear being swallowed; with such cold as this the ice is very strong. Besides, it has a constant tendency to get thicker, for snow falls nine days out of ten, even in April, May, and June, and I fancy it must be something like thirty or forty feet thick."
"That is a comfort," said Johnson.
"In fact, we are very much better off than those who skate on the Serpentine, and who are in constant dread of falling through; we have no such fear."
"Has the resistance of ice been calculated?" asked the old sailor, who was always seeking information from the doctor.
"Yes," the latter answered: "everything almost that can be measured is now known, except human ambition! and is it not that which is carrying us towards the North Pole? But to return to your question, my answer is this. Ice two inches thick will bear a man; three and a half inches thick, a horse and rider; five inches thick, an eight-pound cannon; eight inches, a fully harnessed artillery-piece; and ten inches, an army, any number of men! Where we are now, the Liverpool Custom House or the Halls of Parliament in London could be built."
"One can hardly imagine such strength," said Johnson; "but just now, Doctor, you spoke of snow falling nine days out of ten; that is true, but where does all the snow come from? The sea is all frozen, and I don't see how the vapor can rise to form the clouds."
"A very keen observation, Johnson; but, in my opinion, the greatest part of the snow or rain which we receive in the polar regions is formed from the water of the seas in the temperate zones. One flake arose into the air under the form of vapor from some river in Europe, it helped make a cloud, and finally came here to be condensed; it is not impossible that we who drink it may be quenching our thirst at the rivers of our own country."
"That is true," answered Johnson.
At that moment Hatteras's voice was heard directing their steps and interrupting their conversation. The fog was growing thicker, and making a straight line hard to follow.
Finally the little band halted at about eight o'clock in the evening, after walking nearly fifteen miles; the weather was dry; the tent was raised, the fire lighted, supper cooked, and all rested peacefully.