The hatch-cover was thrown back. For the first time during their captivity they made the discovery that it was night. Looking upwards, they could see a rectangle of dark sky twinkling with stars that, with the slight motion of the submarine, appeared to sway to and fro.
The cool night breeze fanned their heated foreheads as they gained the deck. For some time, coming suddenly from the glare of the electrically lighted interior, their eyes were blinded. They could see nothing but an indistinct blurr of star-lit, gently heaving water.
Gradually the sense of vision returned. They found themselves on the fore-deck of the unterseeboot. They had made up their minds to see a turtle-back deck with a narrow level platform in the centre; instead they found that the deck was almost flat and, in nautical parlance, flush, save where it was broken by the elongated conning-tower topped by the twin periscopes and slender wireless mast.
Lying on the deck in all conceivable attitudes were most of the U-boat's crew, taking advantage of a brief spell on the surface to breathe deeply of the ozone-laden atmosphere.
Not a light was visible on board. Even the hatchway by which the lads had gained the deck was constructed to trap any stray beam from the brilliant glare below.
Miles away, and low down upon the horizon, a white light blinked solemnly; then after a brief interval it was succeeded by a red gleam. This in turn was followed by white again.
Trefusis, with a sailor's inborn instinct, began to count the intervals. Although having no means of consulting the only time-recording watch in the possession of the two captives, he had a fair idea of counting seconds. At fourteen from the disappearance of the red light the white appeared. An almost identical space of time occurred before the red reappeared.
"It's the Wolf Light," mentally ejaculated the lad.
His next step was to fix the bearing of the lighthouse. This he did by looking for the Great Bear, and then, following the Pointers, the North Star.
"Phew!" he muttered softly. "Nor'-nor'-west. This brute of a submarine is right in the chops of the Channel—the main highway for vessels making for London and the south coast ports."