HIP-JOINT. 91 HIPPIAS. the real power by which Uie liead of the femur is retained in the acetabulum wlien the muscles are at rest. DisEA.SE OF TUE HiP-.JoiNT. Hip-disease dif- fers in so many points of importance from other joint-diseases, and is so serious an artection that it requires a special notice. Its connection with the scrofulous or strumous diathesis is more dis- tinctly marked than that of most other joint- diseases, and it almost always occurs before the age of puberty. It is essentially a tubercular inflammation of the hip-joint. Its beginning may be often associated with some trivial occurrence, such as over-exertion in a long walk, a sprain in jumping, or a fall. In the early stage of the disease, the whole of the structures of the joint are inflamed, and by proper treatment at this period the morbid ac- tion may be sometimes subdued without any worse consequences than a more or less rigid joint. Usually, hoiever, abscesses form around the joint, and often communicate with its inte- rior; and the acetabulum, and the head and neck of the thigh-bone, become disintegrated, softened, and roughened. In a still more advanced stage, dislocation of the head of the thigh-bone com- monly occurs, either from the capsular ligaments becoming more or less destroyed, and the head of the bone being drawn out of its cavity by the action of the surrounding muscles, or from a fungous mass sprouting up from the bottom of the cavity, and pushing the head of the bone be- fore it. It is of e.trenie importance that the symptoms should be detected in an early stage of the disease, and surgical aid at once be sought. As the disease advances, abscesses, as already mentioned, occur around the joint, which some- times, from the tension they exert on the obtura- tor nerve, occasion extreme pain in the inside of the thigh. True shortening of the limb now takes place, whic'n at the same time becomes adducted and inverted. From this stage, if the general health is good, the patient may be so fortunate as to recover with an anchylosed (or immovable) hip-joint ; but occasionally a condition of exhaus- tion conies on. the tubercular proco-is exhibits itself in the lung", and elsewhere, and de-atli finally supervenes from the prolonged septic ])rocesses. The duration of the disease may vary from two or three months to ten or more years. The essential factor in the treatment of these cases is complete immobilization of the joint for a protracted period by means of plaster splints or rigid metal braces. With this must be combined nourishing food, fresh air. and sunlight, with general exercise of the body as early as is prac- ticable. HIPPAKCHTJS, hipplir'kus (Lat., from Gk. "Iiriropx»>) ( tl. between B.C. 101 and 12(5). A Greek astronomer and mathematician. He was born in Xictea. Bithynia, hut his astronomical work was done on the island of Rhodes, and pos- sibly also in Alexandria. Of his personal history nothing is known. He was the founder of gen- uinely scientific astronomy, and also of a part of that science which lies on the border-land of astronomy and geometry, viz. trigonometry. In this field he computed a table of chords, which, although lost, is known to us through the works of Theon of Alexandria (q.v. ). who wrote about A.D. .30."). It is probable, too. that this is the Hipparchus who wrote on comlunatorv analysis, and that the Arabs were correct in attributing to Vol. X— 7. him a knowledge of the quadratic equation. Cer- tain it is tiiat Ptolemy was indebted to him for much of the Almagest (q.v.). According to Ka- bricius, Hipparchus wrote nine separate works; but of these onlj' the Commentary on Aratus has come down to us. From the Almagest we learn that it was Hipparchus who first discovered the precession of the equinoxes, determined the place of the equinox among the stars, invented solar and lunar theories, invented the astrolabe (q.v.), and drew up a catalogue of upward of 1000 stars, determining the longitude and latitude of each (this catalogue has been preserved in the Alma- gest). As Ptolemy was also an astronomer, there is some diliicultj' in allotting to each his meed of praise for the discoveries mentioned in the Almagest, which ditliculty has given rise to some discussion. Consult: Delambre, Uistoire de I'astronomie ancienne (Paris, 1817); Berger, Die geograpliischen Fragmente des Hipparch (Leipzig, 1870) ; Wolf, Gesckichte der Astrono- niie (Munich, 1877). HIPPARCHUS (C.5.5.5-.5U B.C.). The son and one of the successors of Pisistratus, tyrant of Athens. On the death of Pisistratus (B.C. .')27), Hipparchus and his older brother., Hippias, kept the government of Athens in their hands. Ilipparcluis interested himself in art and litera- ture, as hi-i father had done. He was murdered by Harmodius and Aristogiton in 514, at the Panathena-a, probably in revenge for a personal insult, though the Greeks of the next century commonly considered the murderers as patriots and saviors of their country. HIPPA'RION (Neo-Lat., from Gk. lirTrdpio^ pony, diminutive of mtttos, hippos, horse). A fossil hor.se, somewhat smaller than the Asiatic ass, remains of which have been found in Upper Miocene rocks of Xorth America and in the Pliocene deposits of North Africa, Asia, and Europe. HIP'PEL, TiiEODOR Gottlieb vox (1741-001. A German humorist and satirist, born at Kijnigs- berg. After traveling in Russia, he settled in his birthplace as tutor and student of law, and in 1786 became Privy Councilor of War and president of the town. He published: Ueber die Ehe (1774. edited by Brenning. 1872); Veber die biirgerliche Verbesserung der Weiber (1792) ; Lebenslaufe nach aufsteipender Linie. nebat Beilagen A. B. C. (1778-81. edited by Ottin- gen, 1883) ; and Ueber weibliche Bildung (1801). In these works he attempted to express and popularize the philosophy of Kant's Kritik, then unpublished. Of a more satiric and political nature are: Zimmermann I. tind Friedrirh I J., von Johann Heinrich Friedrich Qiiittenbaiim Itildschnitzer in Hannover (1790) , and Kreu: und Qufr::;iige des Hitters A. bis Z. His other works include some hymns: the idyllic Hand:eichnuiirien naeh der atur (1790): the drama Drr Mnnn naeh der TJhr (2d ed. 1771); and Veber das Kiiniqsberger Stapelrecht (1791). His collected works were published at Berlin in fourteen- vol- umes (1827-38). Consult his autobiography (Gotha. ISOl). HIPTIAS (Lat., from Gk. "Iirxfoj) ( ?-c.490 B.C.). A tyrant of Athens, son of Pisistratus, upon whose death (B.C. 527) he assumed the government in conjunction with his brother Hip- parchus. According to Thucydides, the govern- ment of the brothers was conducted on the same
