"Yes," replied Forester, "very well."
"They make a floor of boards, I suppose," said Marco.
"No," replied Forester; "they stand directly upon the logs."
"I should think the logs would sink under them," replied Marco, "or at least roll about."
"They sink a little," replied Forester; "just about as much as the bulk of the man who stands upon them."
"I don't know what you mean by that, exactly," said Marco.
"Why, the rule of floating bodies is this," rejoined Forester. "When any substance, like a cake of ice, or a log of wood, or a boat, is floating upon the water, a part of it being above the water and a part under the water, if a man steps upon it, he makes it sink enough deeper to submerge a part of the wood or ice as large as he is himself. If there is just as much of the wood or ice above the water as is equal to the bulk of the man, then the man, in stepping upon it, will sink it just to the water's edge."
"But perhaps one man would be heavier than another man," said Marco.
"Yes," replied Forester; "but then he would be larger, and so, according to the principle, he would make more wood sink before the equilibrium was reached."