In complete ignorance of the presence of the Rioguayan submarine, the group of experts transferred their attention to the seaplane that had detached herself from her consorts and was now hovering in wide circles over the clearly-defined hull of her lawful prey.
A dark object dropped from the fuselage, quickly followed by another, their impact with the water throwing up a tall column of spray.
"What is that fellow doing?" began Uncle Brian, but before he could complete the sentence a muffled roar shook the air. A thick cloud of greasy black smoke shot up, mushroom-shaped... the rush of subsiding water hurled high above the normal surface deadened the long-drawn-out reverberations of the explosion.... The Cariad rolled lazily to the wash caused by the violent displacement of hundreds of tons of water.
It seemed an interminable time before the straight snout and the net-cutting device of the Rioguayan submersible rose for a brief interval above the pool of oil—sufficient for the Cariad to establish the certainty that the craft was not a British one.
The submarine had been hit right aft, the explosion completely shattering the hull abaft the Diesel-engine room. The for'ard portion was, however, still practically intact.
The Cariad's engines were stopped. Captain Parr was seemingly in no hurry to take his ship from that forbidding spot. Nor did he close in order to drop a mark-buoy over the wreckage.
A quarter of an hour had passed. The seaplanes, their work accomplished, were out of sight. The light cruiser still lingered. At the microphone apparatus a grave-faced watch-keeping lieutenant was listening, and not listening in vain, for auricular evidences of what was taking place within the as yet water-tight sections of the submersible.
Suddenly the muffled roar of a second explosion, of lesser magnitude than that of the first, was borne to the ears of the watchers on the cruiser's deck and superstructure. A thin cloud of vile-smelling smoke filtered through the agitated waves and drifted athwart the Cariad.
The Deputy Chief of Staff turned inquiringly to Captain Parr. His hands were trembling perceptibly and his tanned features had assumed a greyish hue.
"Well?" he inquired laconically.