“It’ll take only one or two,” said another.
“Not more than a dozen, anyway.”
But the others, mostly lads capable of real mental exercise, were all cudgeling their brains. It was a subject which had much to be taken into consideration. Presently one senior spoke up:
“It ought to take more than an ounce of them.”
“Nearly as much, anyway.”
“More. That’ll fool you mightily.”
“It looks as though a few brads would do it, but it will take a lot.”
“And why?” asked Mr. Davidson. “Come, what do you say about this?” He again appealed to Bill, turning then also to Gus.
“Well, sir, I think I can see that it will take nearly all of that box of brads, perhaps a hundred. It is a matter of cohesion and even water possesses that, so that to overflow, it will have to rise a good deal above the rim. The area of the glass plus the rise that will be required for the overflow will be, in solid contents, easily as much as that box of loosely filled brads; if they were melted down they wouldn’t be greater than the water area. It is a good deal like the loading of a boat: the displacement is a uniform, compact mass; the load is a jumble with more air space than material. And it is like the floating of a heavy iron pot.”
For answer the lecturer turned and drew a half-pint of water in a glass, brought from his pocket a box of brads and began dropping, one at a time and counting, them into the water. There was profound silence. As the number increased, reaching above two score of the small nails, there began to be heard comments here and there.