"Why, we can't see anything," came a disgruntled chorus.
"Wait a minute," smiled the inventor.
THE BOYS CROWDED ROUND THE WINDOW AND PEERED OUT EAGERLY.
Pressing a button, he extinguished the cabin lights. Then he opened a sort of closet in the wall alongside the window and swung out a powerful, though small, searchlight attached to an adaptable arm in the same manner as a desk telephone.
There was a clicking sound, and a flood of white light pierced the blackness outside. The boys broke into delighted exclamations as the powerful rays revealed all sorts of fish, many of odd shapes and colors, attracted by the light.
Suddenly a dark, shadowy form swung into view. Instantly the other fish vanished, and the boys saw that the newcomer was a large shark swimming leisurely along.
No doubt he wondered who the strangers in his deep sea abode could be, for he swam up close to the window, causing the boys to shrink back. They quite forgot that between them and the tiger of the deep was a solid plate of glass as strong almost as steel.
The shark gazed at the window for an instant and then vanished. With its disappearance, the other fish reappeared and kept the submarine company, for all the world like sea gulls circling round a ship entering port.