When the death of Livingstone brought Africa into prominence again, Stanley, believing he could complete so much of the missionary's work as concerned exploration, turned thither at the head of an expedition under the auspices of the London _Telegraph_ and the New York _Herald_, the object being the survey of the lacustrine system at the head of the White Nile and a journey thence westward across the continent. Leaving Bagamoyo, November 17, 1874, Stanley reached Lake Victoria Nyanza in March, 1875, his journey of seven hundred and twenty miles being marked by pestilential fevers, struggles through thorny jungles, and scant food and water. Circumnavigating the lake, he found it to be over four thousand feet above the ocean, while its proportions--nearly twenty-two thousand miles in area and in places over five hundred feet deep--assumed those of an inland sea. Here Mtesa, a powerful and able negro king, of Mohammedan faith, proved most friendly and greatly aided him, furnishing an escort, which enabled Stanley to explore a part of the adjacent mountain region. From Ujiji he then explored Lake Tanganyika, finding it to be about half the size of Victoria, with an elevation of about twenty-seven hundred feet. [Illustration: Tippu-Tib.] Important as were these discoveries they paled before others, made in following the Lualaba River of Livingstone, which changed the map of Central Africa and altered the destiny of that vast and untraversed region. The journey to Nyangwe, Livingstone's "farthest," entailed horrible hardships on the carriers. This Arab village was reached via the Luama, which, of hitherto unknown course, was found by Stanley to be an affluent of the Lualaba. At Nyangwe Stanley felt that his accomplished journey of over eight hundred miles from the east coast promised well for his coming voyage to a known point on the other coast, nine hundred miles due west. He made an agreement with an Arab, Tippu-Tib, trader in human flesh or ivory as chance offered, to escort the expedition about six hundred miles west through the unknown regions. The country proved to be primeval forest, almost trackless, its tropical undergrowth a veritable jungle of thorns and vines. Game was scanty and other food equally so. Finally, progress was so slow and the path so devious that Stanley, yielding to his appeals, discharged Tippu-Tib and decided to descend the river by canoes and his frame boat. He embarked at Vinya Njara, with one hundred and fifty in his party, on December 28, 1876, intrusting himself with sublime audacity to a river flowing no one knew whither, save it was away from civilization, and with the knowledge that the country they were entering was peopled by tribes entirely hostile and intractable, as the slave-traders said. Day after day they drifted steadily to the north. Was it or was it not the Nile of Livingstone's prediction? Then day by day the course trended to the east. Yes, it could only be the Nile.