Several hours passed, and then, at Lord Hastings’ command, the solid glass front of the submarine was plunged into utter darkness and the powerful searchlight brought to bear on the water ahead, while, at the same time, the speed was reduced to seven knots.
In spite of its powerfulness, the searchlight lighted up the water for only a short distance ahead, and, as Lord Hastings said, should a mine be seen ahead prompt action would be necessary to save them from disaster.
Frank took his place just behind the searchlight, while the compartment behind was closed that no light might enter from without, thus adding a little to the effect of the searchlight.
His watch was set for two hours, and he had sat most of that time with eyes straight ahead, when he became conscious that the door behind him was being pushed slowly open.
Certain in his own mind that his watch was not up, and mindful of Lord Hastings’ order that the door be not opened unless absolutely necessary, Frank nevertheless did not take his eyes off the sea ahead, but called out:
“Who’s there? What is it?”
There was no answer.
“Something wrong,” muttered the lad to himself, and acted upon the instant.
Through the little tube at his elbow he shouted a command:
“Stop her!”