How did Henry Morton Stanley explore the Congo River in the 1870s?

In 1876 and 1877, Henry Morton Stanley led a nine-month expedition that successfully mapped the Congo River by traveling by water from the Lualaba River to the river's mouth.1

During this journey, Stanley and his men were briefly accompanied by the Arab trader Tippu Tib before continuing on their own. Stanley navigated the river to Malebo Pool and proceeded—partly overland—past the great cataracts he named Livingstone Falls, finally reaching the sea on August 12, 1877. This expedition dissipated long-standing geographical uncertainties regarding the river's course and its connection to the Nile system. Stanley later documented this journey in his book Through the Dark Continent (1878).21