“Yeah, well, we just had our second dynamite robbery in two days. Fellow walked into our Merced shop with a coach gun, terrorized the poor old clerk into loading two hundred pounds of dynamite, detonators, and ice tongs on a track inspector’s handcar, and pumped off. We found the handcar three miles down the line next to an empty hayfield. Not a trace of the fellow or the dynamite or the ice tongs.”

“Ice tongs?” Bell echoed, mystified. “What else did he take?”

“Isn’t two hundred pounds of dynamite enough?”

“What else?”

“Hold on! . . . Hey, Tom, Mr. Bell wants to know did he take anything else . . . Oh yeah. Tom says he took a flashlight and some electric cable.”

“What kind of detonators? Fulminate of mercury?”

“Electric.”

“Did you find any truck or wagon tracks?”

“That’s the funny thing. The only wheel tracks were out in the middle of the field. Nothing by the road except footprints. Strange, don’t you think?”

“Not if he came and left on a flying machine!”

“Oh. Never thought of that . . . You still there, Mr. Bell?”

Isaac Bell was running to his American Eagle. “Spin her over!”

The Gnome’s urgent Blat! Blat! Blat! caused Joe Mudd to turn aside and let Bell take off ahead of the Liberator. Bell picked up the Southern Pacific tracks and headed north toward San Francisco. He had less than two hundred miles in which to catch up with Marco Celere.

The stolen electric detonators, the flashlight, and the electric cable were the clues that told Bell exactly what Marco Celere intended to do. He had stolen the ingredients to make an aerial bomb with an electric detonator. Fulminate of mercury detonators that exploded on contact would be deadly on a flying machine that bounced as it took off from the ground and was battered sharply by air currents in the sky. Any sudden motion would make them detonate the dynamite and the flying machine with it.

But an electric detonator could be controlled by a simple switch between the flashlight batteries and the detonators. As long as the switch was off, the dynamite was safe. Switch it on, and the dynamite would explode.

Celere would have fashioned it to be moved into the on position after it was dropped—then only when it fell on its target. He would have installed two switches, one to make the bomb ready at the moment he was ready to drop, the second that would cause the explosion on impact.

Bell could not imagine why Celere had taken ice tongs.

But the rest was clear. Whiteway had refused to let him demonstrate that his machine could win the race, even without Josephine, leaving Celere with no way to prove to the Italian Army that his aeroplane could be a war machine.