"What's the idea of curvin' it?"

"So that it will be stronger and withstand the pressure. You can't break
an arch, you know, and to push this out the hills would have to spread
apart."

"I kind o' see." The old man was thoughtful and looked on silently while
the dam breast stakes were being driven every three feet at the end of a
stretched cord, the other end pivoting on the center stake below, this
giving the required curve.

"How deep you goin' into that hill? Seems like the water can't git round
it now." Mr. Hooper, at a word from Thad, seemed inclined to criticize.

"We must get a firm end, preferably against rock," Bill explained.

"Shucks! Reckon the clay ain't goin' to give none. How much fall you
goin' to git on that Pullet wheel?"

"Pelton wheel. About eighty feet, Professor Gray figured it roughly.
We'll take it later exactly."

"Kin you improve on the Perfesser?"

"No, but he made only a rough calculation. We'll take it both by levels
and by triangulation, using an old sextant of the Professor's. It isn't
a diff----"

"What's try-angleation?" Mr. Hooper was becoming interested.