When John left New-Jersey, he assumed the name of Thomas Cooper, by which he was ever afterward known. He had early in life manifested a religious turn of mind; and this was probably increased by his continual perils and narrow escapes. He mourned over every indication of dishonesty, profanity, or dissipation, among people of his own color; and this feeling grew upon him, until he felt as if it were a duty to devote his life to missionary labors. He became a popular preacher among the Methodists, and visited some of the West India Islands in that capacity. His Christian example and fervid exhortations, warm from the heart, are said to have produced a powerful effect on his untutored hearers. After his return, he concluded to go to Africa as a missionary. For that purpose, he took shipping with his family for London, where he was received with much kindness by many persons to whom he took letters of introduction. His children were placed at a good school by a benevolent member of the Society of Friends; and from various quarters he received the most gratifying testimonials of respect and sympathy. But what was of more value than all else to the poor harassed fugitive, was the fact that he now, for the first time in his life, felt entirely safe from the fangs of the oppressor. He remained in London about a year and a half. During that time he compiled a hymn book which his friends published with his portrait in front. He preached with great acceptance to large congregations: several thousand persons assembled to hear his farewell sermon on the eve of his departure for Africa. He sailed for Sierra Leone, in the latter part of 1818, and was greeted there with much cordiality; for his fame had preceded him. All classes flocked to hear him preach, and his labors were highly useful. After several years spent in the discharge of religious duties, he died of the fever which so often proves fatal to strangers in Africa. His wife returned with her children to end her days in Philadelphia. A CHILD KIDNAPPED.