498
EXPOSITION AT VIENNA.
along the handsome bridge which connects the Surrey side with Cannon Street. Along the bridge run four main lines and one engine line ; in all, five pairs of rails.
“ Between and among these straight lines curved lines meander, touching one pair of rails, cutting across another pair, but, upon the whole, effecting junctions of each with all, and so furnished with points that trains can be run from any one line to any other, as may be required. The five principal lines, as they approach the station, spread out into various branches, so that altogether, nine lines enter the station, one to each of its eight platforms, and the ninth for the accommodation of locomotives. Those branches have also their points, and it results that on the bridge and at the station there are in all thirty-two pairs of points, which serve to guide locomotives and trains to and from the several platforms, and along the various routes which communicate with them. The existence of all these branches necessitates signals, the chief of which number sixteen for up lines and eight for down lines, besides five distant signals and six subsidiar}' signals; making a total of thirt} T -five signals. The number of operations which those points and signals have to conduct may be understood from the fact that, at the most crowded time of the day, eighteen trains arrive and eighteen depart within the hour. The locomotive which brings a train in is at its head, and consequently at the inner end of the station. To bring the train out again, the first locomotive is detached from the inner end, and another locomotive is attached to its outer end, and when it has drawn out the train, the supplanted locomotive moves leisurely out from the platform, and waits quietly by to supplant, in its turn, a brother locomotive, on the arrival of a succeeding train. In this way, for every arrival and departure there are required two movements of locomotives ; and thus, in the crowded hour, no less than 108 operations of shifting points and signals have to be performed, or, on the average, one in every thirty-three seconds.
“ To sum up, we find that thirty-two pairs of points, and thirty- five signals, some of them two hundred yards distant, have to be worked, sometimes to the extent ef 108 operations per hour, and generally to 80 or 90.”
To accomplish this, there is a glass house erected at a short distance from the entrance to the station, over the track, containing thirty-two switch and thirty-five signal levers. During the day, two men are required to tend them, and at night only one. In twenty seconds, the switches and signals can be arranged to transfer a train from one outside track to