Another effective expedient is the central rack rail. No better or more successful example of this method of construction can be given than the Mount Washington Railway, illustrated above. The road was completed in 1869. Its length is 3-1/3 miles and its total rise 3,625 feet. Its steepest grade is about 1 foot rise in every 3 feet in length; the average grade is 1 in 4. It is built of heavy timber, well bolted to the rock. Low places are spanned by substantial trestle work. The gauge of the road is 4 feet 7½ inches, and it is provided with the two ordinary rails and also the central rack rail, which is really like an iron ladder, the sides being of angle iron and the cross-pieces of round iron 1½ inches in diameter and 4 inches apart. Into these plays the central cog-wheel on the locomotive, which thus climbs this iron ladder with entire safety. Very complete arrangements are made to control the descent of the train in case of accident to the machinery. The locomotive is always below the train, and pushes it up the mountain. Many thousands of passengers have been transported every year without accident. [Illustration: A Series of Tunnels.] The rack railroad ascending the Righi, in Switzerland, was copied after the Mount Washington line. Some improvements in the construction of the rack rail and attachments have been introduced upon mountain roads in Germany, and this system seems very advantageous for use in exceptionally steep locations. * * * * * When a line of railway meets in its course a barrier of rock, it is often best to cut directly through. If the grade is not too far below the surface of the rock, the cut is made like a great trench with the sides as steep as the nature of the material will allow. Very deep cuts are, however, not desirable. The rains bring down upon their slopes the softer material from above, and the frost detaches pieces of rock which, falling, may result in serious accidents to trains. Snow lodges in these deep cuts, at times entirely stopping traffic, as in the blizzard near New York, in March, 1888. A tunnel, therefore, while perhaps greater in first cost than a moderately deep cut, is really often the more economical expedient. [Illustration: Tunnel at the Foot of Mount St. Stephen, on the Canadian Pacific. (The glacier 8,200 feet above the Railway.)] [Illustration: Peña de Mora on the La Guayra and Carácas Railway, Venezuela.]