Henry of Huntingdon s Historice was first printed by Savile, Rcrum Anglicarum Scriptores post Bcdam (London, 1586), and it was republished at Frankfort in 1603. Books i., ii. , iv. , v., and vi. were edited by Mr Petrie for the Record Commission Collection, vol. i., 1848; and the whole work has been prepared for the Rolls Series by T. Arnold, 1880. An English translation by Thomas Forester forms a volume of Bohn s Standard Library (1853). We have besides from Henry s pen an Epistle to Henry I. on the succession of the Jewish, Assyrian, Persian, Macedonian, and Roman kings and emperors (written in 1130); an Epistle to Warin (one of his friends) containing an epitome of the British History of Geoffrey of Monmouth, which he had discovered at Bee in Normandy; and, better known than either, an Epistle to his friend Walter On Contempt of tlic World or on Bishops and other Illustrious Men of the Age (written in 1135, and edited by Wharton in his Anglia Sacra, 1691). Nor must Henry s poetical pieces be forgotten, as they speak well for his culture and taste. Two MS. copies of his complete works preserved at Lambeth deserve to be specially mentioned; and the British Museum possesses several important rescripts of the History. See Wright, Bioyr. Brit. Litt., Anglo -Norman Period, 1846 ; Forester s Preface ; James Gairdner, Early Chroniclers of Europe: England (1879); and Arnold s elaborate introductions.
HENRY, Joseph (1797–1878), an eminent American physicist, was born in Albany, the capital of the State of New York, on the 17th of December 1797. He received his education at an ordinary school, and afterward at the Albany academy, which enjoyed considerable reputation far the thoroughness of its classical and mathematical courses. On finishing his academic studies he contem plated adopting the medical profession, and prosecuted his studies in chemistry, anatomy, and physiology with that view. He occasionally contributed papers to the Albany institute, in the years 1824 and 1825, en chemical and mechanical subjects; and in the latter year, having been unexpectedly appointed assistant engineer on the survey of a route for a State road from the Hudson river to Lake Erie, a distance somewhat over 300 miles, he at once em barked with zeal and success in the new enterprise. This diversion from his original bent gave him an inclination to the career of civil and mechanical engineering; and in the spring of 1826 he was elected by the trustees of the Albany academy to the chair of mathematics and natural philosophy in that institution. In the latter part of 1827 he read before the Albany institute his first important contribution, "On some Modifications of the Electro-Magnetic Apparatus." Struck with the great im provements then recently introduced into such apparatus by Mr William Sturgeon of Woolwich, he had still further extended their efficiency, with considerable reduction of battery-power, by adopting in all the experimental circuits (where applicable) the principle of Schweigger s "multi- plier,"^ that is, by substituting for single wire circuits, voluminous coils (Trans. Albany Institute, October 10, 327, vol. i. pp. 22> 23). In June 1828 and. in March 1829 he exhibited before the institute small electro magnets closely and repeatedly wound with silk-covered wire, which had a far greater lifting power than any then known. Henry appears to have been the first to adopt insulated or silk-covered wire for the magnetic coil ; and also the first to employ what may be called the "spool" winding for the limbs of the magnet. He was also the first to demonstrate experimentally the difference of action between what he called a " quantity " magnet excited by a "quantity" battery of a single pair, and an "intensity" magnet with long fine wire coil excited by an " intensity " battery of many elements, having their resistances suitably proportioned. He pointed out that the latter form alone was applicable to telegraphic purposes. A detailed account of these experiments and exhibitions was not, however, published till January 1, 1831 (Silliman s Am. Jour. Sci., xix. 400-408). Henry s "quantity" magnets acquired considerable celebrity at the time, from their unprecedented attractive power, one (August 1830) lifting 750 pounds, another (March 1831) 2300, and a third (1834) 3500.
Early in 1831 he arranged a small office-bell to be tapped by the polarized armature of an "intensity" magnet, whose coil was in continuation of a mile of insulated copper wire, suspended about one of the rooms of his academy. This was the first instance of magnetizing iron at a distance, or of a suitable combination of magnet and battery being so arranged as to be capable of such ac tion. It was, therefore, the earliest example of a true " magnetic " telegraph, all preceding experiments to 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 (Silliman s Am. Jour. Sci., July 1831, xx. 340-343 ; and Sturgeon s Annals Elcctr., 1839, iii. 554). Early in 1832 he discovered the induction of a current on itself, in a long helical wire, giving greatly increased intensity of discharge (Silliman s Am. Jour. Sci., July 1832, xxii. 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 Influ ence 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, February 6, 1835 (Trans. Am. Phil. Soc., v. 223-231, n.s.) In 1835 he com bined 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 dis covered similar successive orders of induction in the case of the passage of Motional electricity (Trans. Am. Phil. Soc., vi. 303-337, n.s.). 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.,. 301). He traced the influence of induction to sur prising 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 feet distant from the wire of the primary circuit. The five num bers 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., iii. 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., iv. 56, 57, and 84, 85). "".In. 1845 he showed, by means of a thenno-galvanometer, .that the solar spots radiate less heat than the general sblitr surface (Proc. Am;. Phil. Soc., iv. 173-176). ^jrnia eJ; ,c;io3 h.i .t.t j jj.
In December 1846 Henry was el.qcteil secretary and, directpri ,o? the Smithsonian Institution, then-just; established.-, , W.hile dosely. occupied with the exacting duties pf r tKat office, he still loVincl time to prosecute many original inquiries^* "iiS -into tint application of acoustics to public buildings, ahdvtheibes l con stmcti&n ah d arrange ment of Iceture-roomSj <iiito the 1 * st reng tfr ofLvaYioiis^ building materials, &c. Having early devotetL nVuqli attention to meteor ology, both in observing and dii reducing and - discussing 1 observa tions, he (among Iris first ictenrnistrative- acts 1 ) organized n Jat gpiqnd widespread conjps of observer^ and atiade arrangements for-simal- taneous repoi bs , i by mean^. afttfte^e Iecituia- telegraph, which. rwas yet in its infancy (SmilHsort.- .-Report far 18,47^ pp. 146, 147). i He was the first to apply the telegraph to meteorological research, io have
