Two binding posts should be mounted on the right hand end of the base so that the engine can be easily connected to a battery. Connect one terminal of the right hand electromagnet to one of the binding posts. Run the other terminal of the electromagnet to the brush on the opposite side of the shaft. Connect one terminal of the left hand electromagnet to the other binding post and run the other terminal to the brush on the opposite side of the shaft. Save for a few minor adjustments, the engine is now ready to run. Connect two or three cells of dry battery to the two binding posts and turn the flywheel so that it moves from right to left across the top. Just as the crank passes "dead centre" and the armature starts to move back away from the left hand magnet, the small contact crank should touch the left hand brush and send the current through the right hand magnet. This will draw the armature over to the right. Just before the armature gets all the way over to the right, the contact should break connection with the left hand brush and interrupt the current so that the inertia of the flywheel will cause it to keep moving and the armature to start to move over towards the left hand magnet at which point the contact on the shaft should commence to bear against the right hand brush, thus throwing the left hand magnet into circuit and drawing the armature over to that side. If the brushes and the cranks are in proper relation to each other the engine will continue to repeat this operation and gradually gain speed until it is running at a good rate. The appearance of the engine can be improved by painting the metal parts black and the flywheel red. The magnets can be wrapped with a piece of bright red cloth to protect the wire against injury and brighten the appearance of the engine. CHAPTER XV. MINIATURE BATTERY LIGHTING. The tungsten lamp has opened wonderful possibilities in the field of electric lighting by means of miniature lamps operated from batteries. The tungsten lamp uses less than one third the amount of current required by the old-fashioned carbon filament lamps in producing the same candle power. This means that the battery will last three times as long. Miniature lighting is one of the most practical phases of experimental electricity to which the experimenter can apply his time. Battery operated lamps will be found invaluable in many places for lighting dark corners, hallways, barns, garages, camps, bungalows, workshops, etc. *Tungsten Battery Lamps* are made in a great many different styles and sizes.