It was nearly two o’clock, and strained nerves were feeling the effect of their prolonged nocturnal adventure. And now a tawny moon rose over the eastern horizon, and under it a golden trail marked the crests of the waves.
“That may help us,” said Fraser.
The light on the float glimmered faintly on the water near the focus of their last barrage. Toward it the three ships steamed, swerving as they approached it so that the supposed point at which the submarine should have sunk would lie in the wake of the moon. As the light on the float was lost among the flashing crests of the waves, the squadron swung into line abreast, and laid its course straight into the shimmering path of gold on the water.
“There!” said Evans eagerly, pointing toward the moon’s wake. “There’s your oil slick, isn’t it, Captain?”
“THERE’S YOUR OIL-SLICK, ISN’T IT, CAPTAIN?”
“Yes—yes, that’s it for sure,” said Fraser. “We’ll examine it a bit.”
As they approached, the smooth patch on the water, spreading across the wake of the moon, was unmistakable. At first a slender line, it widened to a band, as they came nearer, till it clearly covered a large area, spreading out into the darkness on both sides of the moon’s wake.
Slowing down as they approached the edge of the oil slick, they prepared to skim the surface of the water for a sample of the oil, that it might be identified by the chemist at headquarters.
Suddenly Fraser exclaimed, “Hullo! There’s something else. Left rudder.”