Prominent among modern improvements in steam railways is the air brake. This invention is chiefly the result of the ingenuity of Mr. George Westinghouse, Jr., who, beginning his experiments in 1869, took out his first patents on the automatic air brake March 5, 1872, Nos. 124,404 and 124,405, which have since been followed up by many others in perfecting the system. The principle of the air brake is to store up compressed air in a reservoir on the locomotive by means of a steam pump. This air passing through a train pipe connected by hose couplings between cars charges an auxiliary reservoir under each car. This reservoir is arranged beside a cylinder having a piston and a triple valve. Pressure in the train pipe is maintained constantly, and the power to work the piston to apply the brakes comes from the auxiliary reservoir beside it, which is set into action by a sudden reduction of pressure in the train pipe by the engineer through a special form of valve on the locomotive. The air brake is capable of stopping a train at average speed within the distance of its own length, and so great a safeguard to life and property is it, that its application to a certain number of cars on every train is made compulsory by law. The automatic car coupling is another important life-saving improvement. Many thousands of these have been patented, but the “Janney” coupling, patented April 29, 1873, No. 138,405, is the most representative type. The year 1900 is to witness the compulsory adoption of automatic car couplings on all cars. The “block system” of signals, by which no train is admitted on to a given section of track until the preceding train has left that section, improved switches, which are not dependent upon the memory of men, and steel rails, which constitute nine-tenths of all tracks and serve to increase the stability of the track, are further modern safeguards against danger. Sleeping cars were invented by Woodruff, and patented Dec. 2, 1856, Nos. 16,159 and 16,160. These, with the palace cars of Pullman and Wagner, the special refrigerator cars for perishable goods, cars for cattle, and cars for coal, multiply the equipment, swell the traffic, and supply every want of the great railroad systems of modern times. The first railroad in the United States was built near Quincy, Mass., in 1826. The Pacific Railway, the first of our half a dozen transcontinental railways, was completed in 1869. The great Trans-Siberian Railway is nearing completion, and in the Twentieth Century a Trans-Sahara Railway will probably relieve the burdens of the camel, as it has already done those of the horse.