"He's towing the borer!" cried the doctor in exultation. He took up the speaking tube. "Turn back to sea!" he cried. "We passed four destroyers less than ten miles out. We want to get in touch with them."
The plane roared out to sea while Dr. Bird feverishly sounded the "Alnav" call on the radio sending set. In a few minutes an answer came. From their point of vantage they could see flags break out at the peak of the destroyer leader. The four ships turned into column formation and stormed at full speed into the bay. The plane raced ahead to guide them.
"We've got him this time, Doctor!" cried Carnes in exultation. He pointed to the bay below where the submarine was still making its way slowly forward. Dr. Bird shook his head.
"I hope so," he said, "but I have my doubts. Saranoff is no fool. He wouldn't walk into a trap like this unless he had some means of escape. Here comes the first destroyer. We'll soon know the truth."
ith the radio set he directed the oncoming boat. The destroyer reduced to half speed and changed direction slightly. From side to side she maneuvered until she was less than half a mile behind the submarine and headed straight for it. Dr. Bird tapped a few words on his key. With a belch of smoke, the destroyer lurched forward. She cut the waters with her sharp bow, throwing up a wave higher than her decks. Dr. Bird watched anxiously.
The destroyer was almost over the submarine and Dr. Bird's fingers trembled on the key. One word from him would send a half dozen depth charges into the water. On came the destroyer until it was directly over the underseas craft. Dr. Bird pounded his key rapidly.
"Good Lord!" cried Carnes.
From the bump on the side of the submarine came a flash of red light. The destroyer staggered for a moment, and the entire central section of the ill-fated ship disappeared. The bow and stern came together with a rush and went down in a swirling maelstrom of water. The plane lurched in the air as a thundering crash rose from the sea.