REPORT OF MR. ROBERT B. LINES.
487
composed of sections of the track itself, are not subject to wear or derangement ; a safety-signal cannot be shown unless every battery is in working order, and every wire unbroken ; nor can a safety-signal be given when any part of a preceding or meeting" train remains upon the section of track between two signal-stations.
Experiments have been made on a prominent American railway with an apparatus for block and other signalling, the invention of a Mr. Rousseau, based on the well-known principle of the deflection of the magnetic needle by the proximity of a mass of iron. An ordinary compass needle is placed oil a post at the side of the track, and on the passage of the locomotive it is deflected, so as to close a galvanic circuit, by which a semaphore is operated.
Enough has been said, probably, on the subject of " block- signals,” to illustrate the different systems in use and to give the reader an idea of their comparative merits. Several systems, such as Clark’s, Walker’s, Spangoletti’s and Varley’s, requiring the services of a signal-man, have been worked in England more or less satisfactorily. Of two new automatic English systems, Carr’s and Biuney’s, I have been unable to secure descriptions. The latter, however, seems to resemble, in some respects, the system of Mr. Pope. The points of an American system, Robinson’s, are covered it is claimed, by Hall’s and Pope’s instruments.
When the block is worked at junctions, it is known in England as the system of " interlocking points." The best known, perhaps, of these systems, is that of Messrs. Saxby & Farmer, the invention of an employé of the North London Railway, named Chambers. It is not electrical in its operation, but the objects to be accomplished are the same in every system. In the apparatus shown at Vienna, there are two sets of signals, called near and distant, for each line of rails, making eight signals at a double-track crossing. The normal position of the semaphores is at "arrest.” They are worked by a range of levers at the junction, which are so connected that no one of them can be moved so as to put its corresponding semaphore at " line clear,” unless the signals on the crossing tracks are at " arrest.” The levers and semaphores are numbered, and on each lever are also painted the numbers of