Arachnid a

a cla of ARTHROPOD A, the mem- of which breathe by TRACHEA, a series of air running through the body; they have eight no jointed limbs on the abdomen, nor antenne; head and thorax may be united. Many authors the TRILOBITES, LIMULUS ca ei epg (for which see ARTHROGASTRA). ‘The cla is united with the Crustacea as the Acerata, here defined, the cla includes seven orders, viz. (worm-like parasites), A OCARINA TARDIGRADA (water-bears), ARANEID A PHALANGID (harvest-men), PEDIPALP], PSEUDOSCORPIONIDA and SO.I- Representatives of the cla occur first in Silurian period. Arad, (1) a county and chief town in Hungary latter is situated on the right bank of the Maros, 145 miles from Pesth and 60 miles Szegedin. It is the see of a Greek bishop, po e es a citadel, which was in 1849 captured the revolutionary party, and made their head- There is a large trade in corn, and @ that stands third in Hungary. The manufacture is tobacco. This town is called Arad in contradistinction to New Arad, founded 1763 on the other side of the river. The county an area of 2,490 square miles. It is famous for wine, (2) The name of one of the 31 royal conquered by Joshua (Josh. xii. 14), now as Tell’ Arad. 0, FRANGQOIS JEAN DOMINIQUE, an ill us- French physicist, born in 1786. Entering Ecole Poly technique at the age of 17, he was years later appointed a istant to Biot for the urpose of verifying the measurement of the earth. 1809 he received a profe orship in his former became director of the Observatory, and in was elected perpetual secretary of the of Sciences. From 1831 to 1848 he took active interest in politics as a moderate but Republican, and in the latter year was a member of the Provisional Government, marched with the troops against the barricades, which he retired in disgust from public affairs. contributions to science were varied and He finally established the undulatory of light; extended our knowledge of the of polarisation; advanced considerably researches of Oersted and Ampére into the relabetween magnetism and electricity; discovered magnetism, for which he was awarded the medal of the British Royal Society, and many improvements in the construction astronomical instruments. His skill in popuscientific ideas was almost unrivalled, enough, he left behind him no t record of his achievements, though h 188 contributed day, Physique the 1852, consistency. Pyrenees to captaincy-general by by three and flowing parts. summits with almost and ¢ of grain, large not coarse soda. Tar racon ens is, about in The made mained Aragon nand Isabella lising and Arngonite short rayed ns Like is which into south miles Vermelho, the the from length greatest artes) but evaporation its volume. only Azagon. (172 freely to the learned periodicals of his and founded, with Gay-Lu ac, the Annales de ct de Chimie. Arago refused to recognise government established by the Coup d'Etat of and Louis Napoleon honourably respected his Broken in health, he went to his native in the vain hope of recovery, but returning Paris, died in 1854 and received a public funeral. on, sometimes called sits gine now a of Spain, is bounded on the north the Pyrenees, west: by Navarre and Castile, south Valencia, and east by Catalonia. It contains provinces, viz, Huesca, Teruel, and Sarago a, its chief town is Sarago a. The river Ebro, south-east, cuts it into two nearly equal ‘he upper half includes some of the highest of the Pyrenees, and mountains covered forests skirt and indent the country on every side. In the centre there are stony sandy plains, though water is abundantly suplied by the Ebro, the Guadalaviar, the Tagus, the ucar, the Gallego, and the Aragon. It has an area 17,976 square miles. The products are fruit, saffron, hemp, flax, and sheep are reared in numbers. ‘The mineral wealth is great, but exploited. Little is manufactured except woollens, cordage, leather, wine, oil, and Aragon was a part of the Roman Hispania and was wrested from Carthage 200 B.c. The Goths succeeded the Romans 470 A.D., and were expelled by the Moors in 714. kings of Navarre, recovering the territory, it into a dependent country, and so it retill 1035. For the next four centuries was a separate kingdom, but in 1479 Ferdicame to the throne, and having married of Castile united the two realms.