For a brief moment Lord Hastings hesitated, then stepped aside and motioned Frank to his place at the periscope.
"Give the command to fire if anything happens," instructed Lord Hastings.
Frank nodded, and placed his hand on the signal button, at the same time peering into the periscope.
Above everything was perfectly plain. The lad could see that the captain of the liner and some passengers still remained aboard; and, a short distance away, he saw the German submarine, with her commander standing upon the bridge, watch in hand.
Suddenly the German's watch closed with a snap. Frank drew a sharp breath, for he realized what was coming. Slowly the German officer's hand moved upward. Frank divined that he was about to give the signal to fire a torpedo at the defenseless vessel.
Frank's heart leaped into his mouth; and he pressed the little button beneath his finger. And once again the signal board on the U-16 glowed red:
"Fire!"