"Time!" announced Ramblethorne, consulting his watch.
"Are these safe?" asked von Ruhle, stirring Vernon's unconscious form with his foot.
"Quite; though, perhaps, to make sure I will give this youngster a slight injection. Pity you hadn't held him with the double arm-lock instead of cracking him over the head. Herr Kapitan Schwalbe won't want to be troubled with a passenger with a swollen head."
Leaving their senseless victims in the cave, the two Germans again ascended the hill to St. Mena's Chapel. As they breasted the summit, they could see the fixed white light of Black Bull Head showing momentarily brighter and brighter against the rapidly failing daylight.
Setting a prismatic compass in position upon the sill of one of the glazeless windows, Ramblethorne took a careful bearing in a seaward direction. This done, he pointed the projector of the signalling apparatus in precisely the same direction, and threw a waterproofed cloth over the instrument.
"Too early yet, von Ruhle," he remarked. "Nevertheless it is advisable to fix our bearings while twilight lasts. A light might spell disaster."
"A deucedly unpleasant night for such a task," grumbled von Ruhle.
"On the contrary, it is just the very thing," replied the doctor. "It is not thick enough to be dangerous, but the rain is just sufficient to assist in the screening of U75. Do not think of your personal comfort, my dear von Ruhle, when urgent work for the Fatherland has to be undertaken."
For another half-hour the two men paced the grass-grown stones. Their choice of St. Mena's Island as a secret signalling station was an excellent one. It was isolated, and, being slightly greater in elevation than the cliffs of the mainland in the immediate vicinity, would effectually screen any ray of light sent landwards from the expected German submarine. Thus all danger of the narrow gleam of reflected light being detected by the none too smart members of the coast patrol was entirely obviated.
"Time!" exclaimed the doctor, consulting the luminous face of his watch.