Ali’s stories of African life helped somewhat to while away the time for all. This swarthy-cheeked, hawk-nosed Arab had poked his nose into every corner of northern Africa. And, when one considers that the Sahara Desert alone is more than 3,250,000 square miles in extent, or the size of all of the continent of Europe, that meant Ali had done a lot of poking. He was intimately acquainted with the life of every Mediterranean city from Tangiers and Morocco to Port Said. He had crossed the desert by every camel route. He knew the great mountain of Asben in the middle of the Sahara. He had travelled to Timbuktu. He had penetrated to Lake Schad and the sources of the Nile, and had voyaged on the Niger. In a word, Ali was a mine of information on northern Africa. Putting two and two together, he was able even to say he had heard of the Athensians before the Professor brought their existence to his attention. Not that he heard of them by that name, however. He told about it at the camp fire one night, while Jack threw on the blaze several handsful of dried coarse grass and the light leaped high, bringing out the curious faces of the boys and Mr. Hampton and the impassive features of the Arabs. It was from another Arab, a slave trader who had been to Gao, that Ali had the tale. This man Ali encountered at a desert oasis one night. It had been years before. “We were the first travellers who had visited that oasis in a long time,” said Ali. “Some of these isolated oasis are the homes of robbers who raid caravans. But like Sheik Abraham, this sheik was a harmless and pleasant old fellow. He made us feel welcome. We sat on little grass mats on each side of him in front of his tent. Before us was a blazing fire on which his favorite wife now and then, would throw a stick of wood or some grass. She was young, veiled, and her hands were elaborately tattooed. Silver bracelets and ankle-rings jingled at every step. Yes, evidently she was the old patriarch’s favorite wife. “It was very pleasant sitting there, and the woman brought us bowls of _kous-kous-soo_ and tiny brass cups of sweet Moorish coffee on a tray. After eating, we lighted cigarettes and began to talk. We felt it was our duty to tell strange stories of our adventures in order to repay our host’s courtesies. He was a man who did not travel, and it was our duty to entertain.” All paused a long time, staring impassively into the fire. At length he resumed: “Well, the talk passed from this to that, and presently this slave trader began to tell of a strange people from whom every year came to the slave marts of Gao a delegation seeking strong men.