"That's not a bad idea," agreed Mr. Phipps. "With an aeroplane you could follow it at its own speed."
"Of course, Mr. Phipps, an aeroplane would not be an inexpensive proposition, and I do not say it would positively do the work, but the boys are very much interested in aviation and I suggested that they might help me build a biplane here which we could use in clearing up this trouble."
"You mean, let us help in building it?" Herb leaned forward in his chair while Tender Gray's eyes grew large with excitement.
"That was my thought."
"Dad, that'd be great," exclaimed Herb, his dark cheeks flooding with deep-hued red. "Let's do it! You said I could have an aeroplane sometime, anyway."
"I didn't expect to be taken so seriously," laughed Mr. Phipps good-naturedly, though there was no finality in his tone.
During this conversation the boys had been suppressing their anxiety with difficulty. Their eager, impulsive faces changed with every new argument put forth, according to its effect on their project. Only Carlito, the Indian, sat impassive and solemn. But he was paying strict attention to all that was said.
"Hawke ain't talking hard enough," protested Fred in an undertone to Jerry. But Jerry gave him a kick and his lips formed the admonition "keep still."
"How much would the thing cost?" asked Mr. Phipps. Dunk gave Fly a punch with his elbow and Fred hitched his chair closer.
"About a fourth the cost of a factory-built machine," answered Hawke. "You see, I can buy the material at first cost. With the help of the boys it can be built at the fort and I have an engine of my own which I can furnish. Altogether, eight hundred dollars would see us through."