Page:The American Cyclopædia (1879) Volume XVI.djvu/40

 32 TUNKERS the principal buildings are the bey's palace, many handsome mosques, and several large barracks, one of which has room for 4,000 men. There are Moorish schools and a col- lege, a Roman Catholic church and convent, a Greek church, a theatre, and public baths and bazaars. The leading manufactures are wool- len cloths and caps, embroidery, leather, and essences of musk, rose, and jasmine, trade is extensive, comprising exports of oil, caps, soap, grain, wool, hides, cattle, sponges, wax, gold dust, and ivory, and imports of cot- ton, linen, and woollen goods, tin, lead, iron, coffee, sugar, and spices. The depth of water at Tunis is only 6 or 7 ft., and vessels lie in tke gulf and discharge by lighters. In 1873, 1,272 vessels of 121,957 tons entered the port. Tunis is not far from the site of ancient Car- thage, and is itself a place of great antiquity. JUNKERS. See DUNKERS. TUMEL, a subterranean or subaqueous way, constructed for purposes of passage. In mi- ning, the term is often applied to horizontal ex- cavations, especially to such as are known by the designations gangway, heading, drift, and adit, used as underground roads or for the pis- sage of water. (See ADIT.) Herodotus men- tions a tunnel in the island of Samos, cut through a mountain 150 orygia (900 ft.) high. Its length was seven stadia (4,247 ft.), and its cross section 8 ft. high by 8 ft. wide. In Bceo- tia a tunnel was constructed for the drainage of Lake Copais. When Ca3sar arrived at Alex- andria, he found the city almost hollow under- neath from the numerous aqueducts; every private dwelling had its reservoir, supplied by subterranean conduits from the Nile. The aqueducts of the ancient Romans, and of the Peruvians and Mexicans, included remarkable tunnels. (See AQUEDUCT.) Among the many Roman aqueducts on which tunnels were built were the Aqua Claudia, of which 36^ m. passed underground; the Aqua Appia, built in 312 B. C., 11,190 Roman paces in length, 11,130 being underground and arched ; and the Aqua Virgo, 14,105 paces long, 12,865 underground. A tunnel was begun in 398 B. 0. to tap Lake Albanus, at the instance, Livy tells us, of the oracle of Delphi. It was 6,000 ft. long, 6 ft. high, and 3 ft. wide. Fifty shafts were sunk on its line, and the work was finished within one year, though it was driven through the hardest lava. A similar work of greater mag- nitude was undertaken to connect Lake Fuci- nus (now Celano) with the river Liris (now Garigliano) ; 30,000 men were employed on it for ten years, and it was finished at a vast ex- pense A. D. 52. A minute account of the mod- ern clearing out of this work by the Neapolitan government may be found in " Blackwood's Edinburgh Magazine," vol. xxxviii., p. 657. The accuracy of the surveying in these works is astonishing when we consider the rudeness of the instruments. Among those used in levelling by the Romans were the libra aqua- ria and dioptra, of which we have no clear TUNNEL description. The ehorobates seems to have been preferred. It consisted simply of a rod or plank about 20 ft. long, mounted on two legs, at its extremities, of equal length. The rods or legs were secured by diagonal braces, on which were marked correctly vertical lines. Fio. 1. A plumb line attached at each extremity, and passing over these diagonal braces, indicated whether the instrument was level. When the wind prevented the plumb bobs from remain- ing stationary, a channel in the upper edge of the horizontal rod was filled with water, and if the water touched equally both extremities the level was supposed to be correct ; and then the observation of the descent or elevation of the ground was made with accuracy. Tunnel- ling might be classed under four general heads : 1, ancient tunnelling, to which we have just referred ; 2, modern tunnelling through soft ground (clay deposit, &c.) and loose rock, re- quiring arching ; 8, modern tunnelling through solid rock before the introduction of machi- nery ; 4, modern tunnelling through solid rock with the aid of machinery. The art of tunnel- ling at the present day constitutes a profession in itself, now developments succeeding each other with great rapidity. Figs. 1 and 2 show cross sections that may bo adopted in tunnel- ling: fig. 1 through rock tenacious enough to require no artificial support ; fig. 2 where arch- ing may be found necessary. These examples are from plans adopted in the construction of the Musconetcong tunnel, New Jersey, on the FIG. 2. Lehigh Valley railroad extension, finished in 1875. Tunnelling through Soft Ground. Un- der the designation " soft ground," technically so called, the miner includes all such material as clay, earth deposit, &c., which, if tunnelled through, requires a temporary timber arch to