Del Mar threw on a switch. The submarine hummed and trembled. Slowly she sank in the harbor until she was at the level of the underwater entrance through the rocks. Carefully she was guided out through this entrance into the waters of the larger, real harbor.
Del Mar took his place at the periscope, the eye of the submarine.
Anxiously he turned it about and bent over the image which it projected.
"There it is," he muttered, picking out Arnold's yacht and changing the course of the submarine so that it was headed directly at it, the planes turned so that they kept the boat just under the surface with only the periscope showing above.
Forward, about the torpedo discharge tubes men were busy, testing the doors, and getting ready the big automobile torpedoes.
"They must have seen us," muttered Del Mar. "They've started the yacht.
But we can beat them, easily. Are you ready?"
"Yes," called back the men forward, pushing a torpedo into the lock-like compartment from which it was launched.
"Let it go, then," bellowed Del Mar.
The torpedo shot out into the water, travelling under her own power, straight at the yacht.
. . . . . . .
Elaine and I looked back. The periscope was much nearer than before.
"Can we outdistance the submarine?" I asked of Arnold.