BALFOUR STEWART, a noted essayist on scientific subjects, was born at Edinburgh, Scotland, November 1st, 1828. After studying at St. Andrews and Edinburgh Universities, he went to Australia, remaining there seven years and returning in 1853. In 1858 he published his work on “Radiant Heat,” and in 1859 became director of Kew Observatory. In 1870 he was appointed professor of Physics at Owens College, Manchester, and in the next three years published “Elementary Lessons in Physics,” “An Elementary Treatise on Heat,” “Physics Primer,” and “The Conservation of Energy.” The latter work, no doubt the most important of his life, appeared in 1873. He was joint author with Prof. Tait of “The Unseen Universe,” which was published in 1875. He died December 19th, 1887, near Drogheda, Ireland.