Suddenly the lieutenant ceased speaking, and all four, as of one accord, sprang toward the radio instruments.
"Listen!" Lieutenant Mackinson commanded, as he jammed the headpiece over his ears.
"SOS"—the most tragic of all the calls of the sea, was coming to them as a frantic appeal sent out through the air to any and all who might hear and respond.
"SOS," the lieutenant wrote down hurriedly as the message came through space. And then:
"American—Memphis—submarine pursuing—53½ lat.—17 W. lon.—running fifteen knots three points south of west."
The entire message was repeated, and then there was silence—the dense and seemingly impenetrable silence that had existed before.
Came the nearer and more powerful crackle of the radio.
"One of our destroyers is replying," Lieutenant Mackinson announced, and one by one he jotted down the words:
"Continue same direction. U. S. destroyer be with you in about two hours."
"Understand you," the return message came back a moment later. "Submarine still on stern. Has fired two shots, but both missed."