A good mixture to use for bearings is about 1½ teaspoonsful of graphite, to a pint of light machine oil, thoroughly mixed. Graphite can be placed in the crank chamber of a splash feed engine, by means of an insect powder gun. Trouble with oil cups is always in evidence during cold weather, as the oil congeals, and does not drip properly into the bearings. The fluidity of the oil can be increased in cold weather by the addition of about ten per cent of kerosene to the oil. If too much oil is fed to the cylinders, the piston rings will be clogged with gum, and a loss of compression, or a tight piston will be the result. An excess of oil will short-circuit the igniter or sharp plugs, and will form a thick deposit in the combustion chamber that will eventually result in preignition or back-firing. Deposits and gum formed in the cylinder will cause leaky valves and a loss of compression. Feed enough oil to insure perfect lubrication, but not enough to cause light colored smoke at the exhaust. Lubricating systems may be divided into three principal classes: Sight-feed, splash system, and the force feed system. Sight feeding by means of dripping oil cups is too common to require description, and is used on many stationary engines, both large and small. The splash system is in general use on small high speed engines both stationary, and of the automobile type. The force feed system in which oil is fed under pressure by a pump is by far the most desirable as the amount of oil fed is given in positive quantities proportional to the engine speed, and with sufficient pressure to force it past any ordinary obstructions that may exist in the oil pipe. Another system that is half splash, and half force feed, is the pump circulated system much used in automobiles. =THE SPLASH FEED SYSTEM= is the simplest of all, as the bearings are lubricated by the oil spray caused by the connecting rod end splashing through an oil puddle located in the bottom of the closed crank case. The piston and cylinder are lubricated by the spray, as well as the bearings, as the lower end of the piston projects into the crank chamber at the moment that the connecting rod end strikes the oil puddle. To maintain constant lubrication, it is necessary that the oil in the puddle be kept at a constant height, or as in some cases be varied in such a way that the surface of the puddle is raised and lowered in proportion to the load on the engine. In the average engine the oil level is maintained by overflow pipes or openings that allow any excess of oil over the fixed level to flow back to the pump. In the Knight engine the puddles are formed in movable cups which are connected with the throttle in such a way that the opening of the throttle raises the oil level and supplies more oil to the engine at the greater load, or speed.