ELECTRIC SIGNALS ON ENGLISH RAILROADS. 585 



and is about to proceed on its journey to E, and that an ordinary 

 train has preceded it a quarter of an hour, which would allow about 

 time enough for it to " shunt " or go off into the siding at D. When 

 the train has passed the signal-box at C, the signal-man there telegraphs 

 to the one at B that the line is clear, which means that there is no 

 train on the " up " line between stations B and C. Directly the ex- 

 press referred to arrives at B, the signal-man there, if he has received 

 the signal " all clear," allows the train to pass him, and at once tele- 

 graphs to C that there is a train on the " up " line. The C signal-man, 

 if he has received a signal from D of line clear, allows the express to 

 pass him also, but, if not, he exhibits his signal accordingly. We will 

 now suppose that the express is yet between B and C, and that another 

 train, approaching in the same direction, whistles to the man at B for 

 leave to go on. This is refused until the C signal-man telegraphs that 

 the line is c ear. The same plan is carried out at every signal-box 

 the train has to pass, of whatever nature it may be, whether " ex- 

 press," running at the rate of fifty-five miles an hour, or " goods," 

 steaming along easily at a pace of twenty-five. It will thus be seen 

 that, however great the traffic, it can be conducted with almost abso- 

 lute safety, the only difference being that, with a very large number 

 of trains per hour, the signal-boxes are placed nearer together, as on 

 the Metropolitan or Underground Railroad of London, which has as 

 near as possible one thousand trains passing over its system in the 

 course of every twenty-four hours. No accident of any importance 

 has ever occurred on this line. 



But there are other objects in our signal-box besides plungers and 

 little bells to attract attention. Four very noticeable toys — I use the 

 term advisedly, for they struck me at once as being particularly sug- 

 gestive of liliputian railroads, and dolls' houses, and toy signal-men — 

 are the miniature electric semaphores used for instructing the sig- 

 nal-man as to setting the semaphore-signals on the line for the guid- 

 ance of drivers of locomotives. Having stated the principle of 

 the " block " system to be that no two following trains are to be al- 

 lowed to proceed in the same direction upon the same section of line 

 at the same time, it follows that a danger-signal must be exhibited 

 and maintained at the station or depot from which a train has de- 

 parted until it has been cleared out of the section of the line over 

 which it is traveling. To do this effectually necessitates that this 

 signal should be under the control of the signal-man toward whom the 

 train is approaching; and no accident, mechanical or electrical, should 

 be allowed to remove this signal until the train has arrived. The sig- 

 nals used on most of the English lines of railroad to guide the driver 

 are, the raising and lowering of a semaphore arm to denote " danger " 

 and " all clear." If it were possible to work these huge out-door sig- 

 nals by electricity, the system would be perfect ; but, inasmuch as the 

 power of electricity is circumscribed, the production of force sufficient 



