own and laid it with the explosives. Next he called one of the sailors to "boost" him, and was soon perched on the flat slant of a huge rock which formed, as it were, the keystone to the blockade.
"Let's see," he ruminated. "We want a slow charge for this. One that will exert a widespread pressure without much shattering force. The No. 3, I think."
"How is that, Mr. Barnett?" asked the captain, with lively interest.
"You see, sir," returned the demonstrator, perched high, like a sculptor at work on some heroic masterpiece, "what we want is to split off this rock." He patted the flank of the huge slab. "There's a lovely vein running at an angle inward from where I sit. Split that through, and the rock should roll, of its own weight, away from the entrance. It's held only by the upper projection that runs under the arch here."
"Neat programme," commented Trendon, with a tinge of sardonic scepticism.
"Wait and see," retorted Barnett blithely, for he was in his element now. "I'll appoint you my assistant. Just toss me up that cartridge: the third one on the left."
The surgeon recoiled.
"Supposing you don't catch it?"
"Well, supposing I don't."
"It's dynamite, isn't it?"
"Something of the same nature. Joveite, it's called."
Still the surgeon stared at him. Barnett laughed.
"Oh, you've got the high explosives superstition,"
