When the excavation is made by a single wide heading, and a single other cut for removing the bench, which is the method preferred by American engineers, it is called the Heading and Bench method. The work begins by removing a top heading the full width of the section; this heading is usually made 7 ft. or 8 ft. high, and is excavated by the center cut method. The method of strutting usually employed is to erect successive three- or five-segment timber arches, whose feet rest on the top of the bench; when the bench is removed, posts are inserted under the feet of each arch. These arches are covered with a lagging of plank. In America it has often been the practice to let this strutting serve as a temporary lining, and to replace it only after some time, often after years, with a permanent lining of masonry. In a succeeding chapter, some of the methods adopted in relining timber-lined arches with masonry are described. The hauling is done by either narrow or broad gauge tracks laid on the floor of the completed section below. A device called a bench carriage is often employed to enable the cars running on the heading tracks to dump their loads into the cars below, without interfering with the work on the bench front. This device consists of a wide platform carried on trucks, running on rails at the sides of the tunnel floor, so that it is level with the floor of the heading. The front of this platform carries a hinged leaf which may be raised and lowered, and which forms a sort of gang-plank reaching to the floor of the heading. By running the heading cars out on to this traveling platform, they can be dumped into the cars below entirely clear of the work in progress on the bench front. For the purpose of illustrating the two methods of driving tunnels by a heading, which have been briefly described, the St. Gothard and the Fort George tunnels have been selected. The St. Gothard tunnel is selected, as being one of the longest tunnels in the world, and because it was excavated by a number of small parts; and the Fort George tunnel, as being a double-track tunnel, driven by a heading, and bench, and having a concrete lining. ST. GOTHARD TUNNEL. The St. Gothard tunnel penetrates the Alps between Italy and France, and is 9¹⁄₄ miles long. It was constructed in 1872-82. =Material Penetrated.=--The St. Gothard tunnel was excavated through rock, consisting chiefly of gneiss, mica-schist, serpentine, and hornblende, the strata having an inclination of from 45° to 90°. At many points the rock was fissured, and disintegrated easily, and water was encountered in large quantities, causing much trouble.