Popular scientist and Christian teacher, born in Stirling; was educated at Edinburgh and Tubingen; studied for the Free Church; lectured on natural science; became famous by the publication of "Natural Law in the Spiritual World," a book which took with the Christian public at once, and had an enormous sale, which was succeeded by "Tropical Africa," a charmingly-written book of travel, and by a series of booklets, commencing with "The Greatest Thing in the World," intended to expound and commend the first principles of the Christian faith; his last work except one, published posthumously, entitled the "Ideal Life," was the "Ascent of Man," in which he posits an altruistic element in the process of evolution, and makes the goal of it a higher and higher life (1851-1897).