"What does the detector say, Mr. Kenwyn?" asked Captain Restronguet for the tenth time that morning.

"Eighty-three miles, sir."

"H'm; two gained. But it's very strange that that motor-boat should not have noticed the 'Vorwartz.' Perhaps the river is deeper, and Karl von Harburg took the precaution to run submerged."

"It is wide enough for a large craft to pass unnoticed," said Devoran.

"Not the actual channel; if we went half a mile to port or starboard we would be hard and fast aground."

"Is it likely that the 'Vorwartz' has taken to a backwater?" asked Hythe.

"By Jove! I hope not," exclaimed Captain Restronguet; then in a confident tone he added, "No matter, our detector will locate her. One thing we know, she hasn't ascended the Shiré--a tributary that drains Lake Nyassa. I almost wish she had, for I would like to see the final act take place in British waters."

To guard against the tropical heat awnings had been spread fore and aft, extending the whole length and breadth of the deck. Under this the officers and crew not on duty "stood easy," the former seated in deck-chairs brought from the cabins.

To Hythe the voyage seemed more like a pleasure trip than a mission of destruction. He and Kenwyn amused themselves by shooting at crocodiles and hippopotami that frequently came within a hundred yards of the "Aphrodite," while Captain Restronguet did a more practical act by bringing down a bird resembling a turkey, which, falling on the awning, was received as a welcome change to the menu.

Captain Restronguet was in high spirits, but his enthusiasm received a set-back when the "Aphrodite" ran full tilt upon a shoal. It was through no fault of the leadsman. The depth gave six fathoms but a few moments before. The discolouration of the water prevented any indication of the shoaling of the depth from being noticed. It was simply a case of sheer bad luck.