GEM 



GEN 



are unfolded at the same time. This mode 

 of the flower and leaf-bud admits of the 

 following distinctions from the sex of the 

 flowers so produced with the leaves : male 

 flower and leaf-buds as in the pine and fir- 

 tree; female flower and leaf buds as in 

 hazle-nut and horn-bean ; hermaphrodite 

 flower and leaf-buds as in the elm-tree, 

 cornel-tree, mezereon, and almond tree. 



GEMS certain stones, which, on ac- 

 count of their hardness, transparency, 

 and beauty, when cut and polished, are 

 highly esteemed, and, from their small 

 size and scarcity, are valued at very consi- 

 derable price. The gems have been plac- 

 ed among the siliceous fossils, as in some 

 measure allied with them in external cha- 

 racters; and silex was supposed to be their 

 principal ingredient. Bergman first shew- 

 ed the error of this opinion, and proved, 

 by analysis, that in the emerald, sapphire, 

 topaz, ruby, and hyacinth, argil predomi- 

 nates ; their other constituent principles, 

 as discovered by his analysis, being silex, 

 lime, and oxide of iron. Still, however, 

 the old prejudice prevailed, and they have 

 been generally ranked by mineralogists 

 under the siliceous gems. 



The specific distinctions of these fossils 

 were not lessosbcure; they were perplex- 

 ed by the distinctions of the jewellers, 

 drawn from very vague notions : the co- 

 lour, in particular, being the property in 

 which the gems differ most obviously, and 

 which frequently gives them their mer- 

 cantile value, served as a ground of dis- 

 tinction : hence the ruby, the sapphire, 

 and the topaz, were considered as differ- 

 ent, though essentially the same. Another 

 circumstance, added to the confusion thus 

 introduced, was, that other fossils, bearing 

 a resemblance to these gems, had been 

 classed with them ; but, being inferior in 

 lustre, transparency, and hardness, in or- 

 der to distinguish between them, the epi- 

 thet oriental was applied to those which 

 were most perfect ; and, by this contri- 

 vance, fossils were classed under one 

 name, and regarded only as varieties of 

 one species, which were totally different. 

 The Oriental and the Saxon topaz, for ex- 

 ample, were regarded under this point of 

 view, or as varieties of one species, to 

 which the common name of topaz belong- 

 ed, though they are fossils altogether dis- 

 tinct. From these two circumstances, fos- 

 sils were separated, which ought to have 

 been associated, and others were connect- 

 ed, which were specifically different; and 

 it has required much mineralogical discus- 

 sion to disentangle the perplexity, and 

 establish the proper species. 

 Romi de Plsle , threw the first ray of 



light on this subject, by disregarding the 

 colour, and attending rather to the form of 

 crystallization; in consequence of which 

 he arranged together the principal gems 

 named oriental, under the title of the ori- 

 ental ruby. Werner also has placed them 

 under one species, to which he gives the 

 name of sapphire. Hauy has adopted the 

 same arrangement, distinguishing the spe- 

 cies by the name of telesie; and, more 

 lately, Bournon has still farther extended 

 the relations of these fossils, by connect- 

 ing them with the corundum, a fossil 

 which had been brought from India, and 

 which, analysed by Klaproth, was found to 

 be composed principally of argillaceous 

 earth. This, having in general little 

 transparency or lustre, Bournon names 

 imperfect corundum ; while the other va- 

 riety, possessing these qualities, and com- 

 prising the oriental gems, is distinguished 

 by the appellation of perfect corundum : 

 these arrangements have received the 

 sanction of chemical analysis. The skill of 

 Klaproth, of Vauquelin, andChenevix,has 

 been exerted in investigating the compo- 

 sition of these fossils, and they have prov- 

 ed to be argil nearly pure. See DIAMOND, 

 CORUNDUM, TELESIE, RUBY, SAPPHIRE, 

 TOPAZ, AMETHYST, EMERALD, EMERY, 

 BERYL, CHRYSOLTE, CHRYSOBERYLL. 



GENDARMES, or GENS D'ARMES, in 

 the French armies, a denomination given 

 to a select body of horse, on account of 

 their succeeding the ancient gendarmes, 

 who were thus called from their being 

 completely clothed in armour. 



GENDER, among grammarians, a divi- 

 sion of nouns, or names, to distinguish the 

 two sexes. 



GENEALOG1CA arbor, or tree of con- 

 sanguinity, signifies a genealogy or lineage 

 drawn out under the figure of a tree, with 

 its root, stock, branches, &c. The gene- 

 alogical degrees are usually represented 

 in circles, ranged over, under, and aside 

 each other. 



GENEALOGY, an enumeration of a se- 

 ries of ancestors ; or a summary account 

 of the relations and alliances of a person 

 or family, both" in the direct and collateral 

 line. 



GENERAL of an army, in the art of 

 war, he who commands in chief. 



A general ought to be a man of great 

 courage and conduct, to have great expe- 

 rience, and to be of good quality. His 

 conduct appears in establishing his maga- 

 zines in convenient places ; in examining 

 the country, that he may not engage his 

 troops too far while he is ignorant of the 

 means of bringing them off'; in subsisting 

 them ; and in knowing how to take the 



