A tarpaulin, dragged aside, revealed, in the light, a good-sized box-like metallic contrivance, its sides rounded, with a sort of chimney on top: there was, besides, a large, circular tank, and a smalled metal case.
“Here’s a portable projector,” Don identified the metallic object, “and there is the ‘head’ and probably film, in that smaller case. But where does he get his light?”
“Maybe that tank holds acetylene gas,” suggested Chick.
Don, unfastening the projector lamp-house, exclaimed in elation.
“I know!” he cried.
The round, pure white object set in a holder within the lamp-house, identified by Don as a calcium disk, told him the source of light.
“This calcium gives the whitest, most brilliant light there is,” he declared. “See, Chick! The tank probably contains oxygen, under a strong pressure. Yes—there’s a gauge, and a pet-cock to regulate the gas flow. The tank connects, by this rubber hose, to the base of the burner, and the thing on the lamp, like a bent finger, pointing toward the calcium disk, is to throw the oxygen jet onto its surface. Then it glares like all get-out!”
“Let’s row the dory, and never mind the Dart: she’ll stay put,” Chick found oars on the staging in a big box.
They found quite a direct channel, along the shore line from the boathouse to the position in which the helicopter still lay tethered.
Expertly, as Chick obeyed his orders, Don assembled the parts of the apparatus in the cockpit of the helicopter. Iron, or perhaps aluminum, pieces, set into the coaming, enabled them to attach the portable projector, and to swing it to and fro, and direct it up and down.