Stop before crossing railroad tracks, and drive slowly when approaching cross roads. In turning corners to the left, make the turn beyond the center of the cross road. Do not use brakes against the motor--release the clutch. Do not use the brake too forcibly; it will cause injury to rear tires and skidding. On slippery roads, make it a rule to use chains and drive slowly. =244. Care of Car.= Under this heading, a few general rules may be given. Do not persist in running a machine when out of order. Never drive when the lubrication system is working imperfectly. Lack of cylinder oil will ruin a motor in a short time. Make it a rule to look at oil gauge before starting. Care of the battery consists largely in keeping it charged and filled to the proper level with distilled water. Tires should be kept inflated at all times. In case of trouble, never run on a flat tire, as it will soon be worthless under such treatment. Never drive a machine while out of order--stop and have repairs or adjustments made. CHAPTER XXXV LAWN MOWERS; INCUBATORS =245. Operation and Care of Lawn Mowers.= The wheels of the lawn mower permit it both to move easily over the ground and turn the knives which cut the grass (Fig. 139). [Illustration: FIG. 139. Lawn mower.] This means that they must be kept well oiled to work easily--that the shaft of the wheel must not become wrapped with grass, weeds, string or wire. Most machines are made adjustable, and the knives are set to allow them to pass close enough to the plate at the bottom of the mower to clip the grass as if the machine were a pair of scissors. Keep the knives properly adjusted in relation to this plate. Do not let them come so close that they touch the plate but very lightly, nor be so uneven that one end cuts grass, while the other misses the plate so far that it will not cut. If the knives are kept properly adjusted and the mower is not abused by trying to cut wires, stones, or by being stored where it becomes rusty, it will seldom need sharpening. Keep all bolts tight. =246. Storing Mowers.= When storing for the winter, grease the knives with a heavy coat of unsalted lard, or cover them with some other protective material.