Alexander Duff, a Scottish missionary, born near Pitlochrie, Perthshire, about 1806. He entered the university of St. Andrews at the age of 15, and while a student became intimate with Dr. Chalmers. In the summer of 1829 he was licensed to preach. During the later years of his academical studies he was the associate of John Adams and John Urquhart, afterward known in connection with missions. These young students spent much of their leisure time in visiting the poor, distributing tracts, and conducting prayer meetings and Sunday schools in destitute parts of the surrounding country. The churches in Scotland had not yet undertaken any mission to the heathen. When a mission to India was resolved upon, Mr. Duff was selected as the first missionary, and he set sail toward the close of 1829. During his voyage he was shipwrecked on a reef while rounding the cape of Good Hope, and again on the coast of Ceylon. By the first of these mishaps he and his wife lost everything that belonged to them; his plans of operation, his library, and papers were all lost. In India he was kindly received, but not encouraged by his countrymen.

Rammo-hun Roy, however, who had considerable influence over the natives, entered warmly into the views of Duff, and with his assistance a school was commenced under a banian tree with five young men. The shade of the banian was soon too narrow. The studies of the school were accompanied with the daily reading and exposition of the Scriptures. The value of Mr. Duff's labors was very soon apparent both to the native population and their British rulers. His honesty, perseverance, and zeal, in connection with his varied gifts and talents, soon gave a commanding influence to him and the Scottish college which he had established, which ultimately became the largest institution of its kind in India. When intelligence of the disruption of the church of Scotland in 1843 reached Calcutta, Dr. Duff and his brethren at once and unanimously declared their adherence to the Free church, and vacated their institution, with all its valuable library and apparatus. Dr. Duff returned to Europe in 1851 to recruit his health; but he entered on the revival of the missionary spirit among the British people, visiting the churches even in the remotest British isles.

In 1854 he made a voyage to America, visited the principal cities in the northern and western states, and passed through Canada. In 1855 he returned to India, but finally left it in 1863 on account of ill health, and was made professor of evangelistic theology by the general assembly. An endowment of £10,000 had been raised for this professorship, but he refused to accept any salary, stipulating that the income should be given to the cause of missions. He has published "New Era for the English Language and Literature in India" (Edinburgh, 1837), "India and India Missions" (1839), and "Letters on the Indian Rebellion" (1858).