It is of the utmost importance, both for safety and for economy of working, that boilers should be kept clean, that is, free from mud and incrustation. In some sections of the country, especially in the Western States, this is the greatest evil against which locomotive runners and those having the care of locomotives must contend. The cures which have been proposed are numberless, but that which is now chiefly relied upon is, first, the use of the best water that can be procured, and second, frequent and thorough washing out of the boiler. QUESTION 457. _What sort of examination should be given to the boiler attachments?_ _Answer._ It should be observed whether the grate-bars or drop-doors of the grate are properly fastened, and whether the ashes have been cleaned out of the ash-pan, and also whether the fire is clean, that is, whether the grates are free from cinders or clinkers. The height of water in the boiler should be observed by testing it with the gauge-cocks and by noticing it in the glass gauge, if one of the latter is used. It is also well to blow out the sediment and mud from the latter before starting, and to see that the valves which admit steam and water to the glass are open. They should, however, be opened only a very short distance, so that only a small quantity of steam or hot water will escape in case the glass tube should be broken. The injector, if one is used, should be tested to see that it is in working order, and as soon as the engine starts out of the engine house both of the pumps should also be tested, in order to see whether they are in good working condition. The safety-valves should be raised, so as to be sure that they are not rusted or otherwise fastened to their seats. There is no part of a locomotive more liable to disorder than the steam gauge. For this reason it should be frequently tested, and whenever there is any indication of irregularity in its action it should be examined. As the wire netting on the smoke-stack often has holes cut into it by the action of the sparks, it should be frequently examined to see whether it is in good condition. It is also liable to be “gummed up,” especially if too much oil is used in lubricating the cylinders and valves. As soon as holes are cut into the netting there is danger that the sparks which escape will set fire to the combustible material near the track, and if the netting is gummed up the draft will be obstructed and the engine will not make steam. The gummy matter can often be removed by building a wood fire on top of the netting. In this way the oil in the gummy matter is burned up, which leaves a dry material which can then, at least to some extent, be beaten out of the netting. QUESTION 458. _How can it be known whether the pumps are working well?_