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.

"Zowie! Who'd a thunk it?"

"Better just dump 'em all in and start over."

"Don't reckon those nails are soaking the water up; eh?"

"If it were molasses you could fill it half full of brads before it
would slop over."

"Say, look, he's up to sixty! Would you believe that?"

"Hey there, Fatty, you guessed one nail; didn't you----"

"Sixty-eight, sixty-nine, seventy; looks to me like a spill pretty
soon."

"When the freshet starts----"

"It'll drown a lot of people."

Mr. Davidson stopped dropping the nails into the tumbler and held up his
hand.

"There it goes, boys--the first drop over! Eighty-two brads. You can see
who guessed best. The cohesion of the liquid explains it, as our young
friend here has said. I'm glad you have one thinker among you. Now I
want to tell you something about the installation of machinery by
individual motors driven by a central generator, as compared to the
drive from a mill long countershaft and pulleys." And he proceeded with
his talk.

Yes, the lightning had struck. From this moment the respect shown to
Bill, and to Gus also, by those who had no desire to do otherwise was
really almost overdone, his classmates being generally proud of him, and
the teachers and seniors pleased to have him a member of the school. But
the sophs mostly grew more inclined to consider both boys a menace to
their peace of mind.

CHAPTER XIII

QUICK WORK

"I must have t