This consists of a small block of wood having a saw-cut across its upper face and a piece of thin sheet-brass set into the cut. The two rails are placed with their ends abutting and one of these connectors slipped up from beneath and forced on the rails. The piece of thin brass set into the wooden block serves to make an electrical connection between the two rails and also to hold them firmly in position. A small screw and a washer placed outside the track and passing through the brass strip will allow a battery wire to be conveniently attached. [Illustration: Fig. 277.—A Connector for joining the Ends of the Rails.] The steel rails should be occasionally wiped with machine oil or vaseline to prevent rusting, and also to allow the car to run more freely wherever the flanges of the wheels rub against the rails in passing around a curve. Four dry cells or three cells of storage battery should be sufficient to operate the car properly. If it is desirable, a small rheostat may be included in the battery circuit, so that the speed of the car can be varied at will. The motor and the wheels should be carefully oiled so that they will run without friction. The belts should not be so tight that they cause friction or so loose that they allow the motor to slip, but should be so adjusted that the motor runs freely and transmits its power to the wheels. The car may be made reversible by fitting with a small current reverser, but unless the reverser is carefully made the danger of loss of power through poor contacts is quite considerable. If the car is fitted with a reverser the handle should be arranged to project from the car in a convenient place where it can be easily reached by the fingers and the car sent back or forth at will. A railway system such as this can be elaborated and extended by adding more than one car to the line or such features as bridges and stations. [Illustration: Fig. 278.—A Bumper for preventing the Car from leaving the Rails.] The ends of a blind section of track, that is, a straight piece of track not part of a circle or curve so that the car can return, should be fitted with a track bumper, to prevent the car leaving the rails. [Illustration: Fig. 279.—A Design for a Railway Bridge.] No dimensions are given in Figures 279 and 280, showing designs for a bridge and a station, because they are best left to be determined by the scale upon which the railway system is to be extended. [Illustration: Fig. 280.—A Design for a Railway Station.] Both the bridge and the station are very simple. The bridge is built entirely of wood, with the exception of the steel rails. The station may be made out of thin wood, such as cigar-box wood. The doors, windows, etc., may be painted on the walls. If this is carefully done, it will give a very realistic appearance to your station. CHAPTER XIX MINIATURE LIGHTING