"A Jim-what?" queried Jud.
"An electric eel," explained the Professor. "The old priests must have brought them up from the lowlands, and they have thrived here in this warm water ever since. It carries an electric battery in the back of its head, and a big one can give a shock which will stun a strong man. Wait a moment," he went on, "and I'll show you every electric eel within a radius of fifty yards."
As he spoke he fumbled in his knapsack and pulled out a cylinder two feet long, wrapped in waxed paper, with a curious little clockwork attachment at one end.
"I brought along two or three sticks of dynamite equipped with detonators," explained the professor. "They are really small depth-bombs. I thought," he went on, "that if the mud were too deep at the bottom of the lake, a stick or so of dynamite exploded there might stir things up. I'll set this one to go off half-way down, and the shock will stun every living thing in the water for a couple of hundred feet around."
Winding and setting the automatic mechanism so as to explode the bomb at a ten foot depth, the scientist carefully threw one into the water some distance from the raft. Two seconds later there was a dull, heavy plop, and the water shouldered itself up in a great wave which nearly swamped the raft. As it went down, scores of fish of different kinds floated stunned on the surface. Among them were a dozen great green-gold electric eels. As they floated by, Hen slashed each one in two with his machete.
As he finished the last one, Will began to strip off his clothes.
"I can dive twenty feet," he said, "and I'm going to have the next chance at the Inca Emerald."
"No," objected Professor Ditson, "Let Hen try it. He's a great swimmer."
Jud also protested weakly that he wanted to go down again; but Will cut short all further argument by diving deep into the center of the still heaving circle of widening ripples in front of the raft. Even as he did so, Hen, who had stood up to take his place, gave a cry of warning; but it was too late to reach the boy's ears, already deep under the water. Just beyond the circle of the ripples drifted what seemed to be the end of a floating snag; yet the quick eyes of the negro had caught the glint of a pair of green, catlike eyes showing below the tip of a pointed snout which looked like a bit of driftwood.
"It's a big 'gator," he murmured to Professor Ditson, who stood beside him.