had
privately formed an engineering company with Professor Gray as
president, Gus as vice-president, which was largely honorary, and Bill
as general manager and secretary. Advance payments necessary for extra
labor and their own liberal wages were deposited at the Fairview Bank by
Professor Gray and the boys were given a drawing account thereon, with a
simple expense book to keep.

That afternoon, dressed in new overalls and blouses, with a big,
good-natured colored man to help with the laboring work, the boys were
early on the job, at first making a cement mixing box; then Bill drove
the center stake thirty feet below where the dam was to be placed and
from which, using a long cord, the curve of the structure twenty-nine
feet wide, was laid out upstream.

At the spot chosen the rock-bound hillsides rose almost perpendicularly
from the narrow level ground that was little above the bed of the
stream; it was the narrowest spot between the banks. George, the colored
fellow, was set to work digging into one bank for an end foundation; the
other bank held a giant boulder.

The boys were giving such close attention to their labors that they did
not see observers on the hilltop. Presently the gruff voice that they
had heard before hailed them from close by and they looked up to see Mr.
Hooper and the slim youth approaching. The boys had heard that this
Thaddeus was the old man's nephew and that he called the Hooper mansion
his home.

"What you drivin' that there stake down there for? Up here's where the
Perfesser said the dam was to set," Mr. Hooper demanded.

"Yes, right here," Bill replied. "But it is to be curved upstream and
that stake is our center."

"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. Ab