. Operation of trains and station work and telegraphy . difficult to raise op-erators by the telephone as it has been found to be bytelegraph. The use of selective signalling overcomes thisdifficulty entirely,and by the use of a loud ringing bell atthe way station secures immediate attention of the op-erator in charge, if he be within hearing distance, whichmay be two or three hundred feet from the office. Sogreat an advantage has this proven to be that not onlyhave the calls been reduced to a minimum, but the generalefficiency of the service has been materially increased. There are a number o
. Operation of trains and station work and telegraphy . difficult to raise op-erators by the telephone as it has been found to be bytelegraph. The use of selective signalling overcomes thisdifficulty entirely,and by the use of a loud ringing bell atthe way station secures immediate attention of the op-erator in charge, if he be within hearing distance, whichmay be two or three hundred feet from the office. Sogreat an advantage has this proven to be that not onlyhave the calls been reduced to a minimum, but the generalefficiency of the service has been materially increased. There are a number of systems of selective signallingwhich work satisfactorily for a few stations and there areseveral systems which have been designed for a consid-erable number of stations and work to some degree of sat-isfaction when the line conditions are perfect. The prin-cipal defect with these systems is the method of signallingwhich in most cases is a step-by-step method, which isnot only slow but uncertain. In stormy weather the 590 TELEPHONES IN RAILROAD WORK. bis E STATION WORK AND TELEGRAPHY 591 electrical discharges break up the chain of signals andconsequently it is extremely difficult to reach the desiredstation. The dispatcher must find an interval of timebetween lightning flashes sufficiently long for him to op-erate his step-by-step signals, and on a line of consid-erable length this is no easy matter, as it requires but avery small disdharge to place an additional step in thesignal and as a result the wrong party is called. With the system which has been adopted by the Burl-ington Railroad the dispatcher can call any or all stationswith a single operation, while with other systems it isnecessary for the dispatcher to go through as many op-erations as there are stations to be called. The system of selective signalling is of the synchronoustype and uses for its synchronous mechanisms standardlever escapement clock movements. On the dispatchersselector is a dial having fifty-six c
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroa, bookyear1919
