_Answer._ All the wheels of the engine and tender should be carefully examined to see that they are sound. A fracture in a driving-wheel is usually apparent if the wheel is carefully examined. The condition of ordinary cast iron tender and truck-wheels is revealed on striking them with a hammer, when if they are sound they will give out a peculiar clear ring; whereas if they are fractured, the sound produced by the blow of the hammer will be dead, like that of a cracked bell. The flanges of the wheels should also receive attention to see that they are not broken, as such a fracture is not always revealed by the sound produced by a blow from a hammer. The axles too should be examined to see that the wheels have not worked loose on the wheel-seat. When this occurs it often becomes apparent by the oil from the axle-boxes working through between the hubs of the wheel and the axle. This can be observed on the outside of the wheels when the bearings are inside, and inside the wheels when the bearing is outside. The springs should be examined to see that they are in good condition, and the oil-holes in the boxes must be kept clear, so that the oil can reach the bearings. The tender boxes are kept oiled by packing them with cotton or woolen waste saturated with oil. This should be taken out occasionally and renewed and the boxes cleaned. The working of the driving-boxes up and down the jaws will in time wear them so that there will be some lost motion in the jaws. This will be indicated by a thump when the cranks pass the dead point. A similar thump will, however, be produced by lost motion in the boxes of the main connecting-rod, so that it is difficult to determine, without special examination, the cause which produces the concussion. It is therefore best when an engine works with a thump at each revolution for the runner to stand by the side of it where he can touch the connecting-rods and driving-wheels, and then have the fireman open the throttle-valve so as to move the engine slowly. If the lost motion is in the connecting-rods it can be felt by the jar as it passes the dead points. The same is true of lost motion in the jaws, which can be felt by touching the driving-wheels. When the jaws become worn the lost motion can be taken up by moving up one or both of the wedges. When this is done, great care must be taken to keep the centres of the driving-axles the same distance apart on both sides of the engine, and also to keep their centre lines square with the frames. There should always be centre-punch marks placed on the frames or guide-yokes on each side of the engine in front of the main axle, and at equal distances from its centres, so that when the boxes or jaws become worn the position of the axle can be adjusted with a tram from these marks. Of course, if the main axle is square, it is easy to adjust the trailing axle from it with a tram. If the axles are not square with the frames and parallel