this end having been on the galvanometer or needle principle. About the same time he devised and constructed the first electromagnetic engine with automatic polechanger (Sill. Journ., 1831, 20, p. 340; and Sturgeon’s Annals Electr., 1839, 3, p. 554). Early in 1832 he discovered the induction of a current on itself, in a long helical wire, giving greatly increased intensity of discharge (Sill. Journ., 1832, 22, p. 408). In 1832 he was elected to the chair of natural philosophy in the New Jersey college at Princeton. In 1834 he continued and extended his researches “On the Influence of a Spiral Conductor in increasing the Intensity of Electricity from a Galvanic Arrangement of a Single Pair,” a memoir of which was read before the American Philosophical Society on the 5th of February 1835. In 1835 he combined the short circuit of his monster magnet (of 1834) with the small “intensity” magnet of an experimental telegraph wire, thereby establishing the fact that very powerful mechanical effects could be produced at a great distance by the agency of a very feeble magnet used as a circuit maker and breaker, or as a “trigger”—the precursor of later forms of relay and receiving magnets. In 1837 he paid his first visit to England and Europe. In 1838 he made important investigations in regard to the conditions and range of induction from electrical currents—showing that induced currents, although merely momentary, produce still other or tertiary currents, and thus on through successive orders of induction, with alternating signs, and with reversed initial and terminal signs. He also discovered similar successive orders of induction in the case of the passage of frictional electricity (Trans. Am. Phil. Soc., 6, pp. 303-337). Among many minor observations, he discovered in 1842 the oscillatory nature of the electrical discharge, magnetizing about a thousand needles in the course of his experiments (Proc. Am. Phil. Soc., 1, p. 301). He traced the influence of induction to surprising distances, magnetizing needles in the lower story of a house through several intervening floors by means of electrical discharges in the upper story, and also by the secondary current in a wire 220 ft. distant from the wire of the primary circuit. The five numbers of his Contributions to Electricity and Magnetism (1835–1842) were separately republished from the Transactions. In 1843 he made some interesting original observations on “Phosphorescence” (Proc. Am. Phil. Soc., 3, pp. 38-44). In 1844, by experiments on the tenacity of soap-bubbles, he showed that the molecular cohesion of water is equal (if not superior) to that of ice, and hence, generally, that solids and their liquids have practically the same amount of cohesion (Proc. Am. Phil. Soc., 4, pp. 56 and 84). In 1845 he showed, by means of a thermo-galvanometer, that the solar spots radiate less heat than the general solar surface (Proc. Am. Phil. Soc., 4, pp. 173–176).
In December 1846 Henry was elected secretary and director of the Smithsonian Institution, then just established. While closely occupied with the exacting duties of that office, he still found time to prosecute many original inquiries—as into the application of acoustics to public buildings, and the best construction and arrangement of lecture-rooms, into the strength of various building materials, &c. Having early devoted much attention to meteorology, both in observing and in reducing and discussing observations, he (among his first administrative acts) organized a large and widespread corps of observers, and made arrangements for simultaneous reports by means of the electric telegraph, which was yet in its infancy (Smithson. Report for 1847, pp. 146, 147). He was the first to apply the telegraph to meteorological research, to have the atmospheric conditions daily indicated on a large map, to utilize the generalizations made in weather forecasts, and to embrace a continent under a single system—British America and Mexico being included in the field of observation. In 1852, on the reorganization of the American lighthouse system, he was appointed a member of the new board; and in 1871 he became the presiding officer of the establishment—a position he continued to hold during the rest of his life. His diligent investigations into the efficiency of various illuminants in differing circumstances, and into the best conditions for developing their several maximum powers of brilliancy, while greatly improving the usefulness of the line of beacons along the extensive coast of the United States, effected at the same time a great economy of administration. His equally careful experiments on various acoustic instruments also resulted in giving to his country the most serviceable system of fog-signals known to maritime powers. In the course of these varied and prolonged researches from 1865 to 1877, he also made important contributions to the science of acoustics; and he established by several series of laborious observations, extending over many years and along a wide coast range, the correctness of G. G. Stokes’s hypothesis (Report Brit. Assoc., 1857, part ii. 27) that the wind exerts a very marked influence in refracting sound-beams. From 1868 Henry continued to be annually chosen as president of the National Academy of Sciences; and he was also president of the Philosophical Society of Washington from the date of its organization in 1871.
Henry was by general concession the foremost of American physicists. He was a man of varied culture, of large breadth and liberality of views, of generous impulses, of great gentleness and courtesy of manner, combined with equal firmness of purpose and energy of action. He died at Washington on the 13th of May 1878. (S. F. B.)
HENRY, MATTHEW (1662–1714), English nonconformist
divine, was born at Broad Oak, a farm-house on the confines of
Flintshire and Shropshire, on the 18th of October 1662. He
was the son of Philip Henry, who had, two months earlier, been
ejected by the Act of Uniformity. Unlike most of his fellow-sufferers,
Philip Henry possessed some private means, and was
thus enabled to give a good education to his son, who went first
to a school at Islington, and then to Gray’s Inn. He soon
relinquished his legal studies for theology, and in 1687 became
minister of a Presbyterian congregation at Chester, removing
in 1712 to Mare Street, Hackney. Two years later (22nd of June
1714), he died suddenly of apoplexy at Nantwich while on a
journey from Chester to London. Henry’s well-known Exposition
of the Old and New Testaments (1708–1710) is a commentary
of a practical and devotional rather than of a critical kind,
covering the whole of the Old Testament, and the Gospels and
Acts in the New. Here it was broken off by the author’s death,
but the work was finished by a number of ministers, and edited
by G. Burder and John Hughes in 1811. Of no value as criticism,
its unfailing good sense, its discriminating thought, its high moral
tone, its simple piety and its singular felicity of practical
application, combine with the well-sustained flow of its racy
English style to secure for it the foremost place among works
of its class.
His Miscellaneous Writings, including a Life of Mr Philip Henry, The Communicant’s Companion, Directions for Daily Communion with God, A Method for Prayer, A Scriptural Catechism, and numerous sermons, were edited in 1809 and in 1830. See biographies by W. Tong (1816), C. Chapman (1859), J. B. Williams (1828, new ed. 1865); and M. H. Lee’s Diaries and Letters of Philip Henry (1883).
HENRY, PATRICK (1736–1799), American statesman and orator, was born at Studley, Hanover county, Virginia, on the 29th of May 1736. He was the son of John Henry, a well-educated Scotsman, among whose relatives was the historian William Robertson, and who served in Virginia as county surveyor, colonel and judge of a county court. His mother was one of a family named Winston, of Welsh descent, noted for conversational and musical talent. At the age of ten Patrick was making slow progress in the study of reading, writing and arithmetic at a small country school, when his father became his tutor and taught him Latin, Greek and mathematics for five years, but with limited success. His school days being then terminated, he was employed as a store-clerk for one year. Within the seven years next following he failed twice as a storekeeper and once as a farmer; but in the meantime acquired a taste for reading, of history especially, and read and re-read the history of Greece and Rome, of England, and of her American colonies. Then, poor but not discouraged, he resolved to be a lawyer, and after reading Coke upon Littleton and the Virginia laws for a few weeks only, he strongly impressed one of his
