Crane pointed number six visiplate directly into the line of flight and started into the dark water.
"Mow deep are we, Mart?" asked Seaton after a time.
"Only about a hundred feet, and we do not seem to be getting any deeper."
"That's good. Afraid this beam might be going to a station on the other side of the planet—through the ground. If so, we'd have had to go back and trace another. We can follow it any distance under water, but not through rock. Need a light?"
"Not unless we go deeper."
For two hours Seaton held the detector upon that tight beam of energy, traveling at a hundred miles an hour, the highest speed he could use and still hold the beam.
"I'd like to be up above watching us. I bet we're making the water boil behind us," remarked Dorothy.
"Yeah, we're kicking up quite a wake, I guess. It sure takes power to drive the old can through this wetness."
"Slow down!" commanded Crane. "I see a submarine ahead. I thought it might be a whale at first, but it is a boat and it is what we are aiming for. You are constantly swinging with it, keeping it exactly in the line."
"O.K." Seaton reduced the power and swung the visiplate over in front of him, whereupon the detector lamp went out. "It's a relief to follow something I can see, instead of trying to guess which way that beam's going to wiggle next. Lead on, Macduff—I'm right on your tail!"