"We are almost upon the river bank," said Joe. "It was someone rowing, but it sounded to me as though they were using muffled oars."
While the boys stopped to listen, the rowing began again, very slowly, very cautiously, and then there was a muffled splash.
At the same instant a great flashlight to the south began playing first upon the sky, and then, in a slow arc, down the river and then inland toward themselves.
Although they did not come quite within its radius, the boat they had heard was between them and the light! It was a row boat, evidently heavily laden, for it rode low in the water, and it was occupied by one man, who was crouching in the bottom as though to avoid discovery!
Just as suddenly as it had appeared, the searchlight was obscured, and the blackness of the night was more intense by contrast.
"That light was at the navy yard," said Joe, beginning to peel off his coat. "Jerry, you're a fast runner. By heading straight in the way I'm looking you ought to be able to get to the yard in ten minutes. Do it as quickly as you can. Slim will stay here."
By this time Joe had stripped off his shirt and preparing to unlace his shoes.
"And you," blurted Jerry and Slim, almost at the same instant, but still in guarded tones, "what are you going to do?"
"I'm as safe as a duck in the water, and almost as noiseless," responded Joe calmly. "I'm going to swim out and see what is going on. That man out there is a spy!"