A.—­When a tube bursts, a wooden or iron plug must be driven into each end of it, and if the water or steam be rushing out so fiercely that the exact position of the imperfection cannot be discovered, it will be advisable to diminish the pressure by increasing the supply of feed water.  Should the leak be so great that the level of the water in the boiler cannot be maintained, it will be expedient to drop the bars and quench the fire, so as to preserve the tubes and fire box from injury.

754. Q.—­If any of the working parts of a locomotive break or become deranged, what should be done?

A.—­Should the piston rod or connecting rod break, or the cutters fall out or be clipped off—­as sometimes happens to the piston cutter when the engine is suddenly reversed upon a heavy train—­the parts should be disconnected, if the connection cannot be restored, so as to enable one engine to work; and of course the valve of the faulty engine must be kept closed.  If one engine has not power enough to enable the train to proceed with the blast pipe full open, the engine may perhaps be able to take on a part of the carriages, or it may run on by itself to fetch assistance.  The same course must be pursued if any of the valve gearing becomes deranged, and the defects cannot be rectified upon the spot.

755. Q.—­What are the most usual causes of railway collisions?

A.—­Probably fogs and inexactness in the time kept by the trains.  Collisions have sometimes occurred from carriages having been blown from a siding on to the rails by a high wind; and the slippery state of the rails, or the fracture of a break, has sometimes occasioned collisions at terminal stations.  Collision has also repeatedly taken place from one engine having overtaken another, from the failure of a tube in the first engine, or from some other slight disarrangement; and collision has also taken place from the switches having been accidentally so left as to direct the train into a siding, instead of continuing it on the main line.  Every train now carries fog signals, which are detonating packets, which are fixed upon the rails in advance or in the rear of a train which, whether from getting off the rails or otherwise, is stopped upon the line, and which are exploded by the wheels of any approaching train.

756. Q.—­What other duties of an engine-driver are there deserving attention?

A.—­They are too various to be all enumerated here, and they also vary somewhat with the nature of the service.  One rule, however, of universal application, is for the driver to look after matters himself, and not delegate to the stoker the duties which the person in charge of the engine should properly perform.  Before leaving a station, the engine-driver should assure himself that he has the requisite supply of coke and water.  Besides the firing tools and rakes for clearing the tubes, he should have with him in the tender a set of signal