CHAPTER XXVII. A PILOT UNDER COMPULSION. Dawn was just breaking as the "Pique" arrived on the scene of the disaster. Her escape, of which her crew were totally in ignorance, was owing solely to the fact that Karl von Harburg had fired his last torpedo at the ill-fated "Topaze." His means of offence were now reduced, for the power of being able to deliver his antagonist a smashing blow below the surface was no longer possible: he could only ram. Yet the captain of the "Vorwartz" hesitated to attempt to deal thus with the "Pique." The British cruiser had passed within two cables’ length of where the modern buccaneer was running beneath the surface; but the risks to himself by ramming a large armoured vessel travelling at thirty knots were far too great. Seeing that he could render no further assistance Captain Restronguet ordered the "Aphrodite" to be submerged. It was the safest plan, for although he communicated with the "Pique" by wireless, the message was not in code, and the British cruiser, determined to take no risks, might open fire at the submarine. The position of the "Vorwartz" was now, according to the detector, forty miles S.W. of her pursuer. When Captain Restronguet came to fix her position on the chart he knitted his brows in perplexity. The rival submarine was, if his information was correct, actually within the delta of the great Zambezi River. "Now we have her!" exclaimed Captain Restronguet gleefully. "It will be a bit of a shock to Von Harburg when he finds that his return journey is barred by the only craft he feared and one that he thought he had destroyed." "Do you think he’s heard that the ’Aphrodite’ was not smashed up after all?" asked Hythe. "It is doubtful. If he has I can only conjecture that he has decided to ascend the Zambezi in the hope of eluding us. Otherwise I cannot suggest any reason unless he wishes to form a base in this unhealthy Portuguese territory since his Sumatran refuge is closed to him." "I have heard that the district is reeking with fever, sir," remarked the sub. "Many times men-of-war have sent exploring parties up the river and almost invariably some, and once every man, of the crew have been stricken down. The Portuguese have, apparently, taken no active steps to rid the locality of the mosquitoes. If the deadly climate could be rendered habitable, as in the case of the Canal Zone at Panama, the Zambezi would be one of the greatest trading arteries of the world." "Some day it will," said Captain Restronguet. "The British Government has had its eye upon Portuguese East Africa for some time. Could the Portuguese Republic be induced to sell it there would be a splendid outlet for Rhodesia, and under active management the Zambezi would make a splendid waterway. Even now it is navigable as far as Kebrabassa Falls, nearly three hundred miles from the delta."