126 



GELNHAUSEN 



GEM 



Ehilosophy at Athens, after which he practised 

 iw at Rome without abandoning his literary pur- 

 suits. His well-known work, the Noctes Atticce, 

 begun during the long nights of winter in a country- 

 house near Athens, and completed during the later 

 years of his life, is a collection of miscellaneous and 

 ill-arranged matter on language, antiquities, history, 

 and literature, in 20 books, of which the 8th is 

 wanting. It contains many extracts from Greek 

 and Latin authors no longer extant. The best 

 edition is that of Hertz (2 vols. Berlin, 1883-85); 

 see also the same editor's Opuscula Gelliana ( 1886). 



Gelnliaiisen, a town of Prussia, stands on the 

 Kinzig and on the slopes of a vine-clad hill. 26 

 miles NE. of Frankfort-on-the-Main. Here, on 

 an island in the Kinzig, Frederick Barbarossa 

 built an imperial residence ( the ' Pfalz ' ) ; and in 

 1169 he conferred upon the village the freedom of 

 the empire. After being transferred to the counts 

 of Hanau in 1435, Gelnhausen began to decay. It 

 has several old buildings, as the town-house, some 

 towers, the Catholic church, ' princes' house,' &c. 

 Pop. (1895) 4496. 



Gelon, tyrant of Gela and afterwards of Syra- 

 cuse, was a scion of a noble family of the former 

 city, and contrived to become successor to Hippo- 

 crates, its tyrant, in 491 B.C. Six years later he 

 made himself master of Syracuse also, which then 

 became the seat of his government, and to which 

 he transferred the majority of the inhabitants of 

 Gela. His influence soon extended itself over the 

 half of Sicily. Gelon refused to aid the Greeks 

 against Xerxes, as they declined to comply with 

 his demand that he should be appointed com- 

 mander-in-chief. He became embroiled with the 

 Carthaginians because of their attack upon his 

 ally, Theron of Agrigentum, and defeated them in 

 a great victory at Himera, on the same day, accord- 

 ing to tradition, on which the Greeks won the 

 battle of Salamis. The clemency and wisdom of 

 Gelon rendered him so generally beloved that 

 when he appeared unarmed in an assembly of the 

 people, and declared himself ready to resign his 

 power, he was unanimously hailed as the deliverer 

 and sovereign of Syracuse. Gelon died in 478 B.C., 

 and his memory was held in such respect a century 

 and a half after, that, when Timoleon razed to the 

 ground all the statues of former tyrants, those of 

 Gelon alone were spared. 



Gelsemillin nitidum (G. sempervirens), the 

 yellow or Carolina jasmine (nat. ord. Loganiaceae ), 

 is a climbing plant of the Atlantic southern United 

 States, having large, axillary, fragrant, clustered 

 blossoms and perennial dark-green leaves. The 

 dried rhizome and rootlets are used in medicine, 

 and contain an alkaloid, gelsemine, CjjH^NO.,, to 

 which the plant owes its physiological action. 

 When the powdered rhizome, or any of the pharma- 

 ceutical preparations made from it, is taken inter- 

 nally in medicinal doses there ensues a feeling of 

 languor, with slight depression of the circulation 

 and lowering in the frequency and force of the 

 pulse. In larger doses it acts as an active poison, 

 causing cardiac depression, muscular Aveakness, and 

 marked disturbance of vision wide dilatation of 

 the pupil and frequently squinting and ptosis. The 

 central nervous system in man is also affected, the 

 gait becomes staggering, general sensibility is much 

 impaired, the respiration is slow and laboured, and 

 the bodily temperature is lowered. If death results 

 it is from failure of respiration. A solution of the 

 alkaloid applied directly to the eye causes dilata- 

 tion of the pupil and paralysis of accommodation. 

 In medicine gelsemium is used to reduce the tem- 

 perature in malarial and other sthenic fevers ; it is 

 also used in neuralgia, rheumatism, pneumonia, 

 and pleurisy, and by dentists. 



Gelsenkirchen, a modern manufacturing 

 town of Westphalia, 4 miles NW. of Bochum. It 

 owes to coal and iron its rise from a mere village 

 since 1860. Pop. (1880) 14,615; (1890) 28,057. 



Gem, a term often used to signify a precious 

 stone of small size, such as may be used for setting 

 in a ring, or for any similar purpose of ornament ; 

 but sometimes by mineralogists in a sense which 

 they have themselves arbitrarily affixed to it, for 

 the purpose of scientific classification, as the desig- 

 nation of an order or family of minerals, generally 

 hard enough to scratch quartz, insoluble in acids, 

 infusible before the blowpipe, without metallic 

 lustre, but mostly brilliant and beautiful. Among 

 them are included some of the minerals which, in 

 popular language, are most generally known as gems 

 ruby, sapphire, spinel, topaz, bervl, emerald, 

 tourmaline, hyacinth, zircon, &c. and some other 

 rarer minerals of similar character ; but along with 

 these are ranked minerals, often coarser varieties 

 of the same species, which are not gems in the 

 ordinary sense of the word, as emery and common 

 corundum, whilst diamond and some other precious 

 stones, much used as gems, are excluded. See 

 Streeter's Precious Stones and Gems ( 1879 ). While 

 the term gem is thus used currently to denote 

 jewels and precious stones', it is strictly appli- 

 cable only to such hard and precious stones as 

 have been worked by engraving. When the en- 

 graved design is sunk in the stone the gem forms 

 an intaglio, signet, or seal, and when the subject is 

 in relief the gem is a Cameo (q.v. ). The rarer and 

 more costly precious stones, such as the diamond, 

 ruby, emerald, and sapphire, are seldom treated by 

 engraving, because, in addition to the excessive 

 difficulty of working them by engravers' methods, 

 their value principally depends on their brilliance 

 of sparkle and colour. The stories of the gem-en- 

 graver are almost exclusively the variously coloured, 

 mottled, and banded varieties of chalcedony quartz, 

 which are differently named according to the appear- 

 ance they present. From the gem -engraver's point 

 of view, the most important stones are carnelian, 

 sard, chrysoprase, plasma, bloodstone, jasper, agate, 

 and onyx. As these names indicate only differences 

 of colour and shades, degrees of translucency, and 

 alternations of bands, all of which characteristics 

 merge into each other, they are incapable of precise 

 definition. The banded stone, generally called 

 Onyx (q.v.), is used as the principal material for 

 cameo-engraving, the relief subject being worked 

 in one coloured band or stratum on a ground of a 

 different colour. 



The art of gem-engraving developed from the 

 customary use of seals among the ancient Egyptians 

 and other early civilised communities of the East. 

 In addition to abundant remains of seals of high 

 antiquity, we have ample testimony to their im- 

 portant functions from numerous references in 

 early literature. Thus, in 

 Genesis, xxxviii. 18, we 

 read that Tamar demanded 

 of Judah his signet as a 

 pledge ; and Pharaoh, in 

 investing Joseph with the 

 office of principal minister, 

 gave him his signet-ring 

 as a token of authority. 

 The early seals of the 

 Egyptians were cut in 

 the form of the scarabseus 

 or sacred beetle, with the Fig. 1. Carnelian Etruscan 

 intaglio design engraved Scarabaeus : Centaur and 

 in a flat base ; and in this Beer, 

 form they were followed 



by the early Greeks and the Etruscans. Among 

 the Chaldeans, Babylonians, and Assyrians the 

 primitive seals took the form of cylinders, around 



