Page:The New International Encyclopædia 1st ed. v. 09.djvu/470

* GYROSCOPE. 418 GYULA. the opposite direetion. This application was made by Fimeaiilt in 1852. who set his gj'roscope in rotation, anil then with a telescope observed the apparent chansc in the ])lane of its rotation caused by the movement of the earth. GYROSCOPE. The most singular jihenomena shown by the gyroscope are those depending on the composition of rotations. Any motion of a body which has one point fixed is of tlie nature of a rotation about an axis passing through that point. Hence, si- multaneous rotations about any two or more axes, being a motion of some kind, are equivalent to a rotation about a single axis. The eflfeet. then, of impressing upon the frame in which the axis of the gyroscope is suspended a tendency to rotate about some axis, is to give the whole in- strument a rotation about an intermediate axis; and this will coincide more nearly with that of the gyroscope itself, the greater the rate of its rotation. It is hardly possible to explain to the non-mathematical reader the exact nature of the compound motion, but the rotation of the axis of a top round the vertical (when it is not 'sleeping' in an upright position), and the precession of the earth's axis, are precisely similar phenomena. Thus, when the gyroscope is spinning, its axis being horizontal, a weight attached to the frame- work at one end of the axis ( Fig. A ) makes the whole rotate about the vertical. Often the appa- ratus is so arranged that the framework may be lifted by a string attached near one end of the axis ( Fig. B ), and the g;'roscope will then revolve without falling. Its axis still projects horizontally from the string, but it revolves as a whole round the string. Various other singular experiments may be made with this ap- paratus; and others, even more curious, with the gyrostat of W. Thomson ( q.v. ) , which is simply .1 g^'roscope inclosed in a rigid case, by which the ends of its axis are supported. "VMien a gyrostat is made the bob of a pendulum under certain conditions, the plane of vibration of the pendulum turns, as in Foucault's cele- brated experiment, but in general at a much greater rate. The gj'roseope is thoroughly discussed in a treatise by Gen. J. G. Barnard, published in 1S58, and in the following standard works on l)h}'sics: 'iillner, Lehrbiich der Expcrimcntal- lilii/sik- (.5th od., Leipzig, 1894-95) ; Miiller-Pouil- lit-Pfaundler, Lclirhuvh der Physik (nth ed., lirUMswic-k. 1880) : and also in Poggendorfl", Annahn, vol. xc. (Leipzig, 1878). GY'ROSCOP'IC PENDULUM. See Me- CIIAXICS. GYROS'TEUS. See Ctioxdrosteus ; Stur- OEO.N. GYROWETZ, go'ro-vets, Adalbert (1763- 1850). An Austrian composer. He was born at Budwcis, Bohemia, and after studying law at Pragvie. devoted himself entirely to music. In- troduced to the Vienna public through the influ- ence of Jlozart, his first symphonies were re- ceived with marked favor, and he was soon enabled to continue his studies at Naples, Jlilan, and Paris. He afterwards became a favorite of the Prince of Wales at London, and upon his return to Vienna was appointed conductor of the Imperial orchestra. In that capacity he directed the opera from 1804 to 18.'il. He was a very pro- lific composer, writing over 00 symphonies. 40 ballets, and 30 operas, the most popular of the latter being .4j7)ie« Sorei (1811) and Der AiKjen- arzt (1811). His autobiographv was published in 1848. GYTHIUM, jith'i-ura (Lat., from Gk. TMnv). A town in the Polo|)onnesus, on the Laconian Gulf, near the modern. Marathonisi. It lay opposite the island of Cranfe, and was the port of Sparta, 27 miles distant. The harbor was an artificial one, and protected by a breakwater. Its inhabit- ants claimed Apollo and Heracles as the found- ers, but it seems to have been originally a settle- ment of Phncnicians, attracted by the presence of the murcx, which yielded the Pha?nician red dye. It was the ordinary station of the Spartan llect, and in the wars against Athens it was therefore exposed to frequent attacks. Tolmides, the Athenian commander, burned it, B.C. 455. Later it was besieged unsuccessfully by Epam- inondas. B.C. 370. It was strongly fortified by the tyrant Nabis; but he was compelled by Flamininus to give up Gythiuni and other coast towns to the Ach.nean League, B.C. 195. It after- wards became a member of the league of inde- pendent Laconian towns, which after the time of Augustus received the name of the Free Laco- nians. Excavations in 1801 uncovered part of the theatre and of other ancient structures, and there are ninnerous ruins of Roman times in the neigh- borhood. A considerable part of the ancient city seems to be covered by the sea, as extensive ruins can be seen in the bay on a calm day. The site is described by Leake. Le Bas, Ross, Curtius. Philippson. and others in their books on the Peloponnesus, and a good plan is given in Le Bas. Voyage archeologie/ue. Itineraire (Paris, 1888). The excavations are described in the VlpaK-iKa of the Greek Archseologieal Society (Athens, 1891). GYULA, dyijolo. or BEKES-GYULA, ba'- kiish dyoo'lo. Capital of the county of Bekes. Hungary, situated on the White Koriis, in a somewhat swampy district, 45 miles southwest of Grosswardein (Map: Hungary, G 3). It has-