Suddenly Jack, who was at the periscope, perceived a puff of smoke issue from the forward turret of the cruiser, and a moment later a shell plowed up the water near the D-16.
“We’ll have to submerge at once, sir,” he said. “The cruiser has sighted us and takes us for an enemy. One of those shells may hit us.”
“All right,” said Lord Hastings. “First let me have a look.”
He stepped to the periscope, which Jack relinquished to him, and peered ahead. Beyond the cruiser he could make out the periscope of another submarine. Calculating the distance. Lord Hastings gave the order to submerge four fathoms.
Then the D-16 dashed in the direction of the submarine that was seeking to destroy the Russian.
Running at 30 knots, the D-16 soon came upon its prey. A dim bulk suddenly loomed up ahead, some distance higher in the water.
“It’s the enemy,” said Frank, after a careful scrutiny.
“All right,” said Lord Hastings. “Give her a shot before she discovers our presence. We can’t miss at this distance.”
Through the heavy glass in the bow of the submarine Frank watched the effect of the shot. The German submarine staggered suddenly in her stride, then, without a sound, disappeared from sight.
Frank returned to Lord Hastings’ side.