The dory's drift, if unchanged, would take her several yards west of the steel can crowned with its red whistle-cage. Its warning blast set the air vibrating, Oo-oo-oo-ooh!
Jim snatched out his knife and sprang forward.
"Oar in the scull-hole, Perce! Lively!"
Driving the point of his blade into the side of the bow, he dragged the painter in until he reached the gasolene-can. Severing the rope with one quick, strong slash, he scrambled aft and seized the oar.
"Stand by with that painter to jump for the buoy, when I put the bow against it! Better take off your shoes first!"
Percy obeyed. In his stocking feet he would be less liable to slip on the wet iron. Making a loose coil of the painter, he crouched in the bow. Meanwhile Jim had turned the dory round and headed her north of the whistler. A strong current was setting toward the shoal. It took all his strength to scull against it.
Rapidly they neared the can. About eight feet in diameter at the water-line, it tapered to two feet across its flat top, seven feet above. From the circumference rose two iron bails, crossing each other at right angles, several inches above the whistle, which stood two and one-half feet high. A little to one side stuck up the small tube of the intake valve. Round the buoy above the water-line were bolted four lugs, or iron handles, by which the can could be hoisted on board the lighthouse steamer.
As the steel cone sank the whistle bellowed resonantly. Down, down, till the waves swept over its top. Then, slowly it began to rise. The bellowing cut off, and the air rushed into the intake tube.
Percy watched it, fascinated. Jim's voice roused him to their peril.
"Look sharp! Be ready!"