ROLLER BEARINGS.--This type of bearing is ideal because of the large surface which is available. The difficulty is to keep the rollers parallel, with the shaft. Furthermore, they should not roll in contact with each other. To obviate this the rollers are put into a cage. [Illustration: Fig. 101. Cage for Roller Bearing.] FORM OF ROLLER BEARING.--Fig. 101 shows a side and a cross section of a set of rollers held within a cage formed of two end rings A A, each roller B having at its end a reduced bearing C, and intermediate the rollers are tie rods D, which keep the rings in proper relation to each other, and also prevent them from alining themselves diagonally along the shaft, or against the bearing within the boxing. To provide means for utilizing roller bearings so they will take up end thrust, taper rollers are employed, as shown in Fig. 102. [Illustration: Fig. 102. Roller Bearing.] The shaft, or axle, A, has two runways, B, C, which are conically-formed, and inclined toward each other. The rollers D are tapering, and have their small ends pointed towards each other so that the outer ends of the bearing surfaces E of the hub are at a considerable angle to the axis of the shaft. These rollers are also mounted in cages which turn around the shaft. This structure, in a modified form, is largely used in automobile construction. CHAPTER XIV RUNNING AN AUTOMOBILE Don’t look to de right, don’t look to de left; But keep in de middle ob de road. This couplet formed part of an old song long before the automobile was known. It serves as a text for some advice in running a machine. When a novice takes out a car for the first time he feels pretty safe in the block intermediate the crossings, and it is only when he comes to the intersecting streets that he begins to feel that something must be done with the signal or the levers, or both. RUNNING CLOSE TO THE CURB.--If he runs near the curb he will find it necessary to go very close up to the corner before he is able to notice an approach of a vehicle from the right. If he nears the corner running near the middle of the road, it will not be necessary for him to keep such a sharp watch for the sudden appearance of a vehicle, which gives the novice such a fright. THE MIDDLE OF THE ROAD.--For this reason, therefore, the homely advice above, is very appropriate. When in the middle of the road, the looking to the right, or to the left is a matter which is unnecessary. In every community certain local regulations are established, which should be learned, but there are well known rules, which have grown into well recognized laws everywhere, and if they are once understood, will apply wherever you happen to be. COMMUNITY REGULATIONS.--The first of these is to _keep to the right_ in passing a vehicle which is approaching you. The second is, to _pass to the left of a vehicle_ which is going in the same direction.