YOUNG. YOUNG IRELAND. to investigate llie daiif,'ers involved in the intro- duction of illuminating gas in London, and in 1810 he was appointed a member of a commis- sion which was to determine the length of the seconds pcnduhnn. and which also determined the 'Imperial gallon' of ten pounds of water. In ISIS Young became secretary of the Board of Longitude antl superintendent of the Xautical AhiKDKK; in which capacity he served until the dissolution of the lioard in IS2S, when he became the sole conductor of Ihe ?autical Aliiwnac. During the last 3'ears of his life he was a member of a council appointed to advise the Admiralty in scientific matters. Young was the first to de- scribe and measure astigmatism, as well as to study the optical constants of the eye, and ex- plained color sensation by the theory that the eye contained three sets of nerves or receptive systems located at the retina and corresponding to red, green, and violet, and that color-blindness was the result of a deficiency of one or the other of these .systems. Young is often called the founder of physiologieal optics, and his theory was adopted and ain|dified by Helmholtz wdth the result that at present it is generally accepted. His most famous work in ojjties was his demon- stration of the wave theory, which since the time of Huygens (1()90) had made but slight prog- ress. This was accomplished by his discovery of the 'interference of light,' which served to ex- plain the color of thin and thick plates and various other phenomena. Y'oung stated that "radiant light consists of imdulations of the luminiferous ether," and maintained his position in spite of the numerous attacks to which his theories and papers were subjected. ]Iany of the phenomena of polarized light were also dis- cussed by Y'oung, and to him are due many dis- coveries which were later developed by other physicists. To Young is due the use of the terms 'energy' and 'lalior expended.' the former mean- ing the product of the nuiss of a body and the square of its velocity, whereas the latter, which is equivalent to the 'work done,' denotes the products of the force exerted and the distance through which the body is moved, both quantities being proportional to each other. The expression known as Y'oiuig's modulus represents the use of absolute measurements in elasticity and denotes the weight ^^liich would stretch a rod or wire of unit cross-section to double its length. His explanation of capillary phenomena was the first correct one. Y'oung also conducted researches in Egyptology (q.v.), and published an Account of Some Recent Discoveries in IHerogli/phical Literature and Egyptian Aniiquities (1823). He was at work on an Egj-ptian dictionary when he died. Y'oung's work in physics was never adequately appre- ciated by his contemporaries and his countrymen. In fact, his great discovery of interference and its bearing on the undulatorv theory of light was established largely through the activities of Fresnel and Arago. and to them he is indebted for the general recognition which his theory has since received. Y^oung has been described by Helmholtz as "one of the most clear-sighted men who have ever lived, Init he had the misfortime to be too greatly superior in sagacity to his con- temporaries. They gazed at him with astonish- ment, but could not always follow the bold flights of his intellect, and thus a multitude of his most important ideas lay buried and forgotten in the great tomes of the Koyal Society of London, till a later generation in tardy advance remade his discoveries and convinced itself of the accuracy and force of liis inferences." Consult: Peacock, A Life of young; also Miscellaneous Works of Young, edited by I'eacock and Leitch ( London, 1857). His lectures before the Royal Institution have been published in two volumes. YOUNG CHEVALIER, The. A title given to Charles Edward Stuart, son of the Old Pre- tender. YOUNG ENGLAND. A faction of the Conservative Party which had its rise about the year 1843 under the leadership of Disraeli and Lord John Jlanners. It sought to combat the rise of militant democracy bj- bringing about a closer connection between the upjicr classes and the people in the spirit largely of the mediaeval feudalism, adapting itself to modern industrial conditions. The party disappeared in 1845. Dis- raeli has delineated the character of the move- ment in his novels Sybil and Conintjsby. YOUNG EUROPE. An international asso- ciation formed in 1834 on the model of Mazzini's Y'oung Italy (q.v.). It was composed of the national societies of Y'^oung Italy; Young Poland, and Y'oung Germany, which, independent in their own sphere, acted in common, through a central committee, for the furthciing of the principles of liberty, equality, and humanity in Europe. The headquarters of the society were in Switzer- land, -where, in 1835-36, was brought about the organization of a French society, Young France. The activity of the society speedily aroused the opposition of the Swiss authorities, who expelled many of its members from the country. Its in- fluence quickly disappeared. YOUNG GERMANY. The name given to a grou]i of German writers, of whom Heine (q.v.) was the most famous, which in the third de- cade of the nineteenth century initiated a re- volt against the prevailing spirit of romanticism in the national literature, which had resulted in a total separation of literature from the actualities of life. Against the dominant spirit of abso- lutism in polities and obscurantism in religion the writers of this school maintained the prin- ciples of democracy, socialism, and rationalism. Among many things they advocated the separa- tion of Church and State, the emancipation of the Jews, and the raising of the political and social position of women. In 1835 the Federal Diet issued a decree 'forbidding the publication of the works of Heine, Gutzkow, Laube, IMimdt, and Yienbarg (qq.v.). YOUNG IRELAND. A party which had its rise during the agitation Tor the repeal of the Act of Union carried on by O'Connell (q.v.) after 1841, and dilTering from that great leader in their advocacy of forcible means for the at- tainment of their demands. The break between the Y'oung Ireland Party and the conservative section became definite about the year 1844. ' Those who took a prominent part in the move- ment were Thomas Osborne Davis (q.v.), Gavan DulTy (q.v.), .John Mitehel, Thomas Francis Jleagher (q.v.), .John Blake Dillon, and William Smith O'Brien (q.v.). In the Nolion. the organ of the party, the people of Ireland wei'e repeatedly called uj)on to revolt, and in the
