"You couldn't be more mistaken, Mr. Hooper. I'll admit there are a lot of young scamps in Fairview, but these boys, William Brown and Augustus Grier, belong to a more self-respecting bunch. I'll answer for them in every way."

"Of course, Dad, Professor Gray knows about them. Billy and Gus are in our cla.s.s at school." This from the girl who had joyfully greeted the Professor and the boys, yodeling a school yell from the hillside. Then she shot an aside at the slim youth: "You're a regular, downright simpleton, Thad, and forever looking for trouble. Don't listen to him, Dad."

This appeared to settle the matter. Mr. Hooper squared his shoulders and grinned broadly, adding: "Well, I ain't just satisfied 'bout them knowin' how, but go to it your own way, Professor. I'm a goin' to watch it, you know; not to interfere with your plans an' ways, but it's got to be done right. If it goes along free an' fine, I ain't goin' to kick."

The Professor explained that they had further work to do on the plans and must be going back. He took leave of Mr. Hooper and the daughter, and retreated with the boys as hurriedly as Bill could manage his handy crutch. They all proceeded silently in crossing the broad field, but when in the road Bill had to voice his thoughts:

"I expect that old fellow'll make it too hot for us."

"Not for a minute; you need not consider that at all. Of course it would be more satisfactory if Mr. Hooper could be a.s.sured at once of your real ability, but it will have to grow on him. Just let him see what you can do; that's all."

"I rather expect we can frame up something that will satisfy him and Bill can spring it," said Gus.

"In just what way, can you imagine?" queried the Professor.

"Some geometrical stunt, maybe; triangulation, or--"

"Why, sure! That's just it!" exploded Bill. "I know how we can get him: Parallax! Shucks, it'll be easy! Just leave it to me."

"Looks as though some kind of Napoleonic strategy were going to be pulled off," a.s.serted Professor Gray, laughing. "But, boys, keep in mind that Mr. Hooper, while a rough-and-ready old chap, with a big fortune made in cattle dealing, is really an uncut diamond; a fine old fellow at heart, as you will see."

CHAPTER XI

ENGINEERING

Two busy days followed during which Bill and Gus went to the city with Professor Gray to purchase materials in full for the power plant. They also had cement, reinforcing iron, lumber for forms and a small tool house hauled out to the power site and they drove the first stakes to show the position of wheel and pipe line. Mr. Hooper did not put in an appearance.

On the third morning the Professor bade the boys good-by, exacting the promise that they would write frequently of their progress. They 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. 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 s.e.xtant of the Professor's. It isn't a diff----"

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

"The method of reading angles of different degrees and in that way getting heights and distances. That's the way they measure mountains that can't be climbed and tell the distance of stars."

"Shucks, young feller! I don't reckon anybody kin tell the distance o'

the stars; they only put up a bluff on that. They ain't no ackshall way o' gittin' distance onless you lay a tape measure, er somethin' like it on the ground. These here surveyors all does it; I had 'em go round my place."

Bill smiled and shook his head. "I guess you just haven't given it any consideration. There are lots of easier and better ways. Triangulation.

Now, for instance, suppose an army comes to a wide river and wants to get across. They can't send anybody over to stretch a line; there may be enemy sharp-shooters that would get them and it is too wide, anyway. But they must know how many pontoon boats and how much flooring plank they must have to bridge it and so they sight a tree or a rock on the other sh.o.r.e and take the distance across by triangulation. Or suppose--"

"Never heard of it. Why wouldn't surveyors git from here to yan that a-way, 'stead o' usin' chains? Could you----?"

"Chaining it is a little more accurate, where they have a lot of curves and angles and the view is cut off by woods and hills. Yes, we can work triangulation; we could tell the distance from the hilltop to your house if we could see it and we had the time."

"Bunk! Don't let 'em bluff you that a-way, Uncle. Make 'em prove it."

Thad showed his open hostility thus.

Gus dropped his shovel and came from the creekside where he had begun to dig alongside of the stakes for the foundation. He was visibly and, for him, strangely excited as he walked up to Thad.

"See here, fellow, Bill can do it and if there is anything in it we will do it, too! You are pretty blamed ignorant!"

Mr. Hooper threw back his head and let out a roar of mirth. "Well, I reckon that hits me, too. An' I reckon it might be true in a lot o'

things. But Thad an' me, we kind o' doubt this."

"We sure do. I'd bet five dollars you couldn't tell it within half a mile an' it ain't much more than that."

"I'll take your bet and dare you to hold to it," said Gus.

"Bet 'em, Thad; bet 'em! I'll stake you."

"Oh, we don't want your money; betting doesn't get anywhere and it isn't just square, anyway." Bill was smilingly endeavoring to restore good feeling. "Now, Mr. Hooper, we're not fixed to make a triangulation measurement to-day, but----"

"Not fixed? Of course not. Begins with excuses," sneered Thad.

"But to-morrow we'll bring out Professor Gray's transit and show you the way it's done."