Page:The New International Encyclopædia 1st ed. v. 18.djvu/720

STREET RAILWAY. These various methods fall into seven classes as follows: Traction by steam motors, by compressed air, by gas motors, by carbonic acid engines, by ammonia engines, by cables, and by electricity. Steam, gas, compressed air, and vapor motors have been employed in comparatively isolated instances and under special conditions, although they have been the subject of considerable experimentation and are to be met with occasionally in Europe and to a less extent in the United States. The only systems of mechanical propulsion which have attained extended use in America (leaving elevated railways out of account) are cable power and electric motors. The development of electric propulsion for street cars is described in the article on.

for city passenger service had their origin in San Francisco, and it was at first thought that the system was only applicable to straight lines with heavy grades in favorable climates, but this view was changed when cable traction was established in Chicago on level lines with sharp and difficult curves and was operated despite snow and other climatic disadvantages. As a result an enormous impetus was given to the construction of cable railways in America and such lines were built in a score or more of American cities. In 1886 the Tenth Avenue and 125th Street cable road was put in operation in New York City, and several years later this was followed by the Third Avenue line, 12 miles long, and the Broadway and Lexington Avenue lines. In 1891 there were 70 cable street railway lines in operation in the United States, with an aggregate mileage of 577½ miles. The new construction and extension of the next two or three years increased this total to about 700 miles, which marked the height of the cable railway in America. Since that time the mileage has steadily decreased under the competition of electric traction, until in 1900 there were but 300 miles of cable railway in operation in the United States.

In construction the cable railway consists of a standard street railway track having an underground conduit between the rails. In this conduit there runs an endless wire rope cable guided by suitable pulleys. A slot at the top of the conduit permits a grip projecting downward from the bottom of the car to enter the conduit. This grip is provided at its lower end with jaws which can be so operated from the platforms of the car as to grasp and unloose the cable at will. Generally in modern practice duplicate cables are installed in the conduit, the purpose of which is to have a second cable ready for operation in case of breakage or other accident. Movement is given to the cable by means of a revolving drum around which the cable is wrapped, these drums being operated by powerful steam engines installed in power houses located at intervals along the line. Generally speaking, it is not desirable to operate a greater length of cable than 25,000 feet, but cables as long as 39,000 feet have been successfully operated. The prevalence of curves is perhaps the most important factor determining the length of cable which can be operated. As a general rule it is found that a right angle curve puts a strain upon the cable plant equal to that entailed upon it by 1000 feet of straight road. It may be assumed that from 40 per cent. to 60 per cent. of the power used in operating a cable railway is consumed in operating the cable itself. The size of cable most generally used is 1¼ inches, and the material favored is crucible steel. The life of street railway cables averages about fourteen months, giving from 70,000 to 80,000 miles of service, but there are records of cables having given 144,000 miles of service. In a few cases, of which the New York and Brooklyn Bridge is notable, the cable is not inclosed in a conduit, but is carried on pulleys above ground or on an elevated structure.



In respect to street railway transportation generally the most notable facts are the enormous growth of street railways in mileage and capital invested, and the predominant position held by electric traction for street railway operation. Both of these facts are graphically illustrated in the accompanying diagrams, compiled by the Street Railway Journal. In the ten years