If the pipes are burst with only a small fracture, it can usually be remedied by covering the aperture with canvas or rubber and wrapping twine around it tightly. The upper valve of a pump must, however, never be taken down without first being sure that the check-valve is tight, because if it is not, the person will be likely to be scalded in taking the pump apart. Directions for managing an injector, and also for taking care of pumps in cold weather, have already been given in the answers to Questions 142 and 488. QUESTION 519. _What should be done in case of the breaking or bursting of a cylinder or cylinder-head?_ _Answer._ The main connecting rod must be taken down on that side of the engine. The piston should then be moved to the front or back end of the cylinder and wooden blocks be placed between the guides so as to fill up the space between the cross-head and the end of the guide-bars, and thus prevent the cross-head and piston from moving. The valve stem should then be disconnected from the rocker, and the valve moved to the middle of the valve face, so as to cover up both steam-ports. It must then be fastened in that position by screwing up _one_ of the bolts of the stuffing-box of the valve stem, so as to make the gland bind against the valve stem. The train should then be run cautiously to the next station with the use of _one_ cylinder. If the engine is not able to haul the train with one cylinder, then it should be uncoupled from the train and run to the first telegraph station or other point where the aid of a helping engine can be obtained or telegraphed for. In the meanwhile the train must be protected by the proper signals. Should the engine continue its journey with one cylinder, it must be started, if it should happen to be standing at the dead point, by _pushing_ or by means of _crow-bars_. In so doing, however, the bars should not be put between the spokes of the wheels, as they may easily be caught in the wheels when the engine starts, and in this way the spokes be broken or the persons who are using the crow-bars be badly hurt. QUESTION 520. _What must be done in case a steam-chest or steam-pipe is broken?_