"He asked me, innocent as you please, if a steel bridge couldn't be made in a single span, and I said, yes, but it would take too long. We only had a few days. 'Well,' he says, 'Mr. Bannon, I'll give you a permit.' And that's what he gave me. I bet he's grinning yet. I wonder if he'll grin so much about three days from now."
"Do you mean that you can build it anyway?" Hilda demanded breathlessly.
He nodded, and, turning to Pete, plunged into a swift, technical explanation of how the trick was to be done. "Won't you please tell me, too?" Hilda asked appealingly.
"Sure," he said. He sat down beside her at the desk and began drawing on a piece of paper. Pete came and looked over his shoulder. Bannon began his explanation.
Illustration: ["HERE'S THE SPOUTING HOUSE">[
"Here's the spouting house, and here's the elevator. Now, suppose they were only fifteen feet apart. Then if we had two ten-foot sticks and put 'em up at an angle and fastened the floor to a bolt that came down between 'em, the whole weight of the thing would be passed along to the foundation that the ends of the timbers rest on. But you see, it's got to be one hundred and fifty feet long, and to build it that way would take two one hundred-foot timbers, and we haven't got 'em that long.
Illustration: [HE WAS DRAWING LINES ACROSS THE TIMBER]
"But we've got plenty of sticks that are twenty feet long, and plenty of bolts, and this is the way we arrange 'em. We put up our first stick (x) at an angle just as before. Then we let a bolt (o) down through the upper end of it and through the floor of the gallery. Now the next timber (y) we put up at just the same angle as the first, with the foot of it bearing down on the lower end of the bolt.
"That second stick pushes two ways. A straight down push and a sideways push. The bolt resists the down push and transmits it to the first stick, and that pushes against the sill that I marked a. Now, the sideways push is against the butt of the first timber of the floor, and that's passed on, same way, to the sill.
Illustration: ["WELL, THAT'S THE WHOLE TRICK">[