While waiting for supplies in Unyanyembe, Dr. Livingstone wrote a second letter to Mr. James Gordon Bennett, which was principally devoted to the slave trade of East Africa, to greatly aid in the abolition of which would be more gratifying to the explorer’s ambition than to discover all the sources of the Nile. This might well be supposed from what has already been quoted from Dr. Livingstone’s despatches to his government; but inasmuch as he here directly appeals to the American people, this volume would be incomplete without the remarkable and most thrillingly interesting statements of the letter in question. They were sent by cable telegram from London and appeared in the “Herald” newspaper of July 27, 1872: “At present let me give a glimpse of the slave trade, to which the search and discovery of most of the Nile fountains have brought me face to face. The whole traffic, whether by land or ocean, is a gross outrage on the common law of mankind. It is carried on from age to age, and, in addition to the evils it inflicts, presents almost insurmountable obstacles to intercourse between different portions of the human family. This open sore in the world is partly owing to human cupidity, partly to the ignorance of the more civilized of mankind of the blight which lights chiefly on more degraded piracy on the high seas. (_sic._) It was once as common as slave trading is now, but as it became thoroughly known the whole civilized world rose against it. “In now trying to make Eastern African slave trade better known to Americans, I indulge the hope I am aiding on, though in a small degree, the good time coming yet when slavery as well as piracy will be chased from the world. Many have but a faint idea of the evils that trading in slaves inflicts on the victims and authors of its atrocities. Most people imagine that negroes, after being brutalized by a long course of servitude, with but few of the ameliorating influences that elevate the more favored races, are fair average specimens of the African man. Our ideas are derived from slaves of the west coast, who have for ages been subject to domestic bondage and all the depressing agencies of a most unhealthy climate. These have told most injuriously on their physical frames, while fraud and the rum trade have ruined their moral natures so as not to discriminate the difference of the monstrous injustice.