Tyn'dall, John, an eminent British scientist, was born at Leighlin Bridge, Carlow, Ireland, Aug. 21, 1820; and died in Surrey, England, Dec. 4, 1893. He was educated in the public schools until 19, when he entered the employ of the ordnance survey. After a short teaching experience he went to the University of Marburg in 1848, where he spent two years and took his doctor's degree. In 1851 he went to Berlin, where he made the valuable acquaintance of Magnus, Clausius, Wiedemann and others. Returning to London in 1852, he was elected fellow of the Royal Society, and in the year following was appointed professor of natural philosophy in the Royal Institution, succeeding Faraday, a position which he held until 1887, when he was succeeded by Lord Rayleigh. Tyndall's earliest investigations were made at Marburg on The Magneto-Optic Properties of Crystals. In 1859 he began an important study of Radiant Heat, resulting in a classical volume in 1872. His investigations of glacier motion were reported to the Royal Society in 1856, and later recorded in interesting popular volumes. As a skillful and brilliant lecturer on science he has, perhaps, never been surpassed. Every one should read his Heat as a Mode of Motion and his Forms of Water.