TYNDALL, JOHN ) , British natural philoso pher, was born in Co. Carlow, Ireland, on Aug. 2, 182o. Tyndall was to a large extent a self-made man; he was stimulated to earnest study by the writings of Carlyle. He passed from a na tional school in Co. Carlow to a minor post (1839) in the Irish ordnance survey, thence (1842) to the English survey, attending mechanics' institute lectures at Preston in Lancashire. He then became for a time (1844) a railway engineer, and in 1847 a teacher at Queenwood College, Hants. Thence with much spirit, and in face of many difficulties, he betook himself, with his col league Edward Frankland, to the university of Marburg (1848 1851), where, by intense application, he obtained his doctorate in two years. His dissertation was an essay on screw-surfaces.
Tyndall's contributions to science are due more to his person ality and his gift for making difficult things clear rather than to his original researches. He became known through some early magnetic investigations and was elected F.R.S. in 1852. In May 1854 he was chosen professor of natural philosophy at the Royal Institution, a post which exactly suited his striking gifts and made him a colleague of Faraday, whom in 1866 he succeeded as scientific adviser to the Trinity House and Board of Trade, and in 1867 as superintendent of the Royal Institution. His rev erent attachment to Faraday is beautifully manifested in his memorial volume called Faraday as a Discoverer (1868).
With his friend Huxley he went to Switzerland to study the motion of glaciers; his views brought him into conflict with Forbes and James Thomson.
Tyndall's investigations of the transparency and opacity of gases and vapours for radiant heat, which occupied him during many years (1859-1871), are frequently considered his chief scientific work. (See HEAT.) But his activities were essentially many-sided. He definitely established the absorptive power of clear aqueous vapour—a point of great meteorological signifi cance. He made brilliant experiments elucidating the blue of the
sky, and discovered the precipitation of organic vapours by means of light. He called attention to curious phenomena occurring in the track of a luminous beam. He examined the opacity of the air for sound in connection with lighthouse and siren work, and he finally verified what had been already substantially demon strated, viz., that germ-free air did not initiate putrefaction.
Tyndall's devotion to science for its own sake may be seen in his treatment of the money which came to him in connection with his successful lecturing tour in America (1872-1873). He placed the money amounting to several thousand pounds in the hands of trustees for the benefit of American science—an act of lavish ness which bespeaks a noble nature. He took some part in the controversy over theological problems which was going on at the time. He died at Hindhead on Dec. 4, For the substantial publication of his researches reference must be made to the Transactions of the Royal Society; but an account of many of them was incorporated in his best-known books, namely, the famous Heat as a Mode of Motion (1863 ; and later editions to 188o), the first popular exposition of the mechanical theory of heat, which in 1862 had not reached the text-books ; The Forms of Water, etc. (1872) ; Lectures on Light (1873) ; Floating Matter in the Air 0880 ; On Sound (1867 ; revised 1875, 1883, 1893). The original memoirs themselves on radiant heat and on magnetism were collected and issued as two large volumes under the following titles: Diamagnetism and Magne-crystallic Action (187o) ; Contributions to Molecular Physics in the Domain of Radiant Heat (1872).