JOHN TYNDALL was born at Leighlin Bridge, Ireland, August 21st, 1820. At the age of twenty-four he began life in the employment of an engineering firm, but a little later he became a teacher at Queenwood College, Hants, and began the course of study and scientific investigation which made him famous. After three years (1848–51) at the University of Marburg, he began making the contributions to the literature of physics which were valued by the learned for their subject-matter and read with pleasure by the general public because of a lucidity of statement which made the difficult things of science seem simple. In 1852 Tyndall was elected a Fellow of the Royal Society, and a year later he became professor of Natural Philosophy in the Royal Institution of London. His investigations of heat, light, and electricity resulted in a series of works of great scientific value, and he wrote besides several volumes of essays specially designed for popular reading. Of these, “Fragments of Science for Unscientific People” (1871) proved so popular that it was followed in 1892 by “New Fragments.” Prof. Tyndall died in Surrey, England, December 4th, 1893.