Abstract :
It has been common practise to use five lamps in series in street railway lighting service where line voltages run about 550 or 600 volts. The lamps regularly used in such service have heretofore been of the straightfilament, vacuum type, rated in wattages 23, 36, 56 and 94 but otherwise similar to the old type of lamps used for multiple lighting service. Gas-filled lamps of ordinary construction cannot be used satisfactorily in series on the high line voltages used in street railway service. The chief cause for unsatisfactory operation is the maintaining of the arc in case the filament is broken while burning. The surrounding gases hold it in a persistent manner due to the high voltage back of it, and eventually the arc becomes destructive.
