Tunnel

(tun'n'l.) [From Fr. tonnelle, a little ton.] (Civ. Engin.) A subterranean opening or pa age cut through a hill, or under a river, town, ., to carry a line of road, canal, or railway in a direct and even course. The greatest T. in existence is that of Mont Cenis (q. v.). The Hoosic T., intersecting the Hoosic range of mts., in Ma achusetts, between the Deer field andHoosic rivers, is, after that of MontCenis, the longest in the world, its extent being 4 18 miles. It is on the Troy and Greenfield line of railroad, and, when complete,which is expected by March 1,1874, will serve as the shortest mode of communication between the East and the West. This T. presented at the outset extraordinary difficulties to be encountered and surmounted; and it was not until Dec. 1868, that there seemed any promise of succe . At that date a contract was entered into, to finish the tunnel first begun in 1852, with Me rs. Walter and Francis Shanly, Canadian engineers of eminence, who commenced upon the work in the following March, and who are to receive for completing the work $4,594,268, making its entire cost about nine million of dollars. After early failures to tunnel the mountain by means of machinery, the work was for a long time carried on by means of hand-drills and gunpowder. At length a new drill, invented by Mr. Chas. Burleigh of Fitchburg, Ma ., was tried and adopted. It consists ofa simple cylinder and piston worked by air compre ed by enormous forcing pumps kept in motion by water-or steam-power. Cartridges of nitro-glycerine ignited by electrical fuses Fig.652. TUNNEL ON THE SHORES OF LAKE WALLENSTADT, (SWITZERLAND.) are used in the blasting operations in the harder parts of the rock; also dua line, a much le dangerous substance than nitro-glycerine. The T. has 3 shafts, the central one of which is 1,034 feet in depth. Fig. 652 represents a picturesquely located T. on the railway route bet. Zurich and Coire, Switzerland, being the first of a succe ion of five which carry the line of rails along the shores of Lake Wallenstadt, and which are pierced with apertures on the lake-side-affording magnificent views of the surrounding scenery. Tunny, (tun'ne.) [ Fr. thon.] (Zool.) See SCOMBRIDE. Tunstall, (tün's tal,) a manuf. town of England, co. Stafford, 4 m. N.E. of Newcastle-under-Lyme. Pop. 27,795. [s. 911]