The estuary formed an ideal base for Captain Cain's new sphere of operations. Nominally within the limits of Rio del Oro—Spain's extensive, unproductive and loosely-held dependency, stretching from Morocco on the north to French Senegal on the south—the Wad-el-Abuam was hardly ever visited by vessels, except Moorish coasters and fishing craft.
The entrance to the river was a difficult one, a bar on which the surf broke heavily, extending practically right across it, although well on the starboard hand was a narrow channel carrying twenty feet at high water and protected by a long, narrow rocky island that not only served as a breakwater, but also effectively screened the estuary when viewed from seaward.
Within the bar the depth increased to sixty feet, with a bottom of firm white sand. Farther up, the bed was composed of mud that became more objectionable as the width of the river decreased. The banks were almost destitute of vegetation, consisting of sand with a few palms and a scanty scrub that afforded meagre food for goats belonging to the inhabitants. There were four or five small villages populated by a tribe of savages, half Arab, half Negro, who had long resisted any attempt at subjection on the part of the Spanish troops stationed at Villa Cisnero and other fortified posts of Rio del Oro.
Within two hundred miles lay the Canary Islands, with Funchal, the favourite port of call for ships running between Europe and the west and south coasts of Africa. Farther to the south'ard was Teneriffe, with Las Palmas, another frequented coaling-station. Both these were within the Alerte's wireless radius, so that the pirates hoped to obtain a fairly complete report of all vessels passing within striking distance of their proposed base.
"I suppose we haven't made a mistake," remarked Pengelly, as the Alerte slowly approached the land. "I can't see any sign of an estuary."
"It must be there," replied Cain, after consulting the latest but far from reliable chart of this part of the coast. "We'll stand in a bit more. If there's any doubt about it, we'll send a boat and take soundings. The sailing directions state that the island is hardly distinguishable from the mainland except at short distance."
He levelled his binoculars for the twentieth time during the last hour.
"By thunder!" he exclaimed. "Hanged if there isn't a sail coming round the point. Native craft, by the cut of her."
"That's awkward," remarked the second in command. "We don't want company of that sort. She's heading towards us."
"Let her," said Cain, with his characteristic grim smile. "Let her. Mr. Marchant, serve out the small arms. Get up the machine-gun, but keep it out of sight until it might be wanted. We'll nab that fellow and make the crew pilot us in."