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Page:Collier's New Encyclopedia v. 10.djvu/49

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TUNNEL

33

TUNSTALL

are now paved. The whole town has been built of materials taken from the ruins of Carthage, 13 miles N. E. The bazaars of Tunis are good, and some of the mosques are splendid edifices, but Europeans are jealously excluded from them. The Bey's palace is a modern building in the Saracenic style of architecture, internally decorated with great magnificence, but with little taste. The city has many schools and colleges, French and Jewish, and in the Great Mosque is also a Mohammedan college. Tunis has important manufactures of woolen, linen, and silk goods (which are exported to all the Mohammedan countries bordering on the Mediterranean), morocco leather, olive oil, soap, and perfumes. A canal opened in 1893 renders Tunis directly accessible to ocean-going vessels. Pop. about 200,000.

TUNNEL, in engineering, a horizontal or slightly inclined gallery beneath the surface of the ground; generally used for an aqueduct or for the passage of a railway, roadway, or canal. In the construction of railroads it is frequently necessary to pierce the hills, so as to preserve a line of road as nearly level as practicable. The method of proceeding with tunneling depends mainly upon the kind of material to be excavated. This having been generally ascertained by borings and trial shafts, the work is commenced by sinking the working shafts, which must be sufficiently capacious to admit readily of lowering men and materials, raising the material excavated, fixing pumps, and also for starting the heading of the intended tunnel when the required depth is reached. Besides the trial and working shafts, air shafts are sunk for the purpose of effecting ventilation in the works below. Tunnels when not driven through solid rock have usually an arched roof, and are lined with brickwork or masonry. In mining, a level passage driven across the measures or at right angles to the veins which it is its object to reach. Thus distinguished from the drift or gangway which is led along the vein when reached by the tunnel.

The Great Divide Tunnel.—A notable engineering feat was accomplished in 1893 in the completion of the boring of the Busk-Ivanhoe railway tunnel under the continental divide of the Rocky Mountains at Hagerman Pass, Col. The tunnel is almost two miles long—9,393 feet—and is through solid gray granite. It took three years and 20 days, of 20 hours' work each day, to make the excavation. It is 10,800 feet above sea-level, through the top ridge of the continent. The water draining from the one side of the mountain, under which it is driven, runs to the Atlantic Ocean, and from the other to the Pacific. Its construction cost $1,000,000 and 20 human lives. The tunnel substitutes two miles of track for 10 and does away with one of the most expensive railway climbs in the world. Among more recent tunnels are those under the Hudson and East rivers in New York City.

TUNNY, a member of the mackerel family, or Scombridæ with somewhat the appearance of gigantic mackerel. There are several genera and species. The common tunny (Thynnus vulgaris of Cuvier, Orcynus thynnus of Gunther) is the thynnus of the ancients. It is a large fish, reaching nine feet in length, and 1,000 pounds in weight. It occasionally occurs on the British coasts, but is particularly abundant in the Mediterranean. It has a large mouth with small teeth, two dorsal fins, the first elongated and reaching nearly to the second, which is shorter; behind the second dorsal and anal are eight or nine finlets like those of the mackerel. There is a keel on each side of the free portion of the tail, and the tail fin is crescentic. There are small scales all over the body, but they are larger in the anterior part, where they form a well-defined corselet. An air bladder is present. The tunnies approach the coasts in summer, chiefly for the purpose of spawning, and it is at this time that the fishery is carried on. Like the mackerel the fish are gregarious and migratory, but it is untrue that they all leave the Mediterranean in autumn, as was formerly supposed. The Phoenicians established a tunny fishery at a very early period on the coast of Spain, and the tunny appears on Phoenician medals of Cadiz and Carteia. Salted tunny was much esteemed by the Romans, and was called Saltamentum Sardicum.

TUNSTALL, CUTHBERT, an English clergyman; born in Hackforth, Yorkshire, in 1474; brother of the Sir Brian Tunstall who fell at Flodden; was educated at Oxford, Cambridge, and Padua, and became in turn Rector of Stanhope, Archdeacon of Chester, Rector of Harrow-on-the-Hill, Master of the Rolls, Dean of Salisbury (1521), Bishop of London (1522), and of Durham (1530). In 1516 he went on an embassy to Charles V. at Brussels, and there formed a fast friendship with Erasmus. Between 1516 and 1530 he was often employed on embassies to France and Germany, and in 1527 he had accompanied Wolsey on his magnificent embassy to France. He accepted the Royal Supremacy, but took alarm at the sweeping measures of reform under Edward VI.,