isolated lighting plants for hotels; suburban residences and farms; railway switch and signal service; railway car lighting; interlocking switch service; United States Government submarine and gunfiring service; telephone, telegraph, wireless and fire-alarm service; laboratory and school work; electroplating; automobile enginestarting; gas-engine ignition; automobile lighting; electric trucks and pleasure cars; street railway cars; electric launches and mine and industrial locomotives.

The Storage Battery for Gasoline-Engine Ignition.-Because of the almost universal employment of electricity for lighting and starting ystems, the battery ignition system has been improved materially, inasmuch as the storage battery supplying the current is constantly charged by a generator. A number of systems have been devised, these operating on two different principles, the open circuit and the closed circuit. An example of the closed-circuit system is shown at Fig. 54, and is of Connecticut design, the complete ignition system consisting of a combined timer and hightension distributor, a separate induction coil and a switch. The system is distinctive in that the timer is so constructed that the primary circuit of the coil is permitted to become thoroughly saturated with electricity before the points separate, with a result that a spark of maximum intensity is produced. The action is very much the same as that of a magneto on account of the saturation of the winding. Another feature is the incorporation with the switch of a thermostatically operated electro-magnetic device, which automatically breaks the connection between the battery and the coil should the switch be left on with the motor idle.

The contact-breaker mechanism consists of an arm A carrying one contact, a stationary block B carrying the other contact, a fiber roller R, which is carried by the arm A, and operated by points on the cam C, which is mounted on the driving-shaft. Normally, the contacts are held together under the action of a ight spring. As the four cams, which in touching the roller R "aise the arm and separate the contacts, are 90 degrees for a fourvlinder motor, the period of saturation of the coil or the length time the current flows through it to the battery is sufficiently so that when the points have separated, the current, which

has "piled" up, induces an intensely hot spark at the plugs. This is an advantage, inasmuch as it insures prompt starting and regular ignition at low engine speed, as well as providing positive ignition at high engine speed.

The thermostatic circuit-breaking mechanism is very simple. This consists of the thermostat T, which heats when the current passes through it for from thirty seconds to four minutes without interruption, and thus is bent downward, making contact with the contact L. This completes an electrical circuit, which energizes the magnets M, causing the arm K to operate like the clapper in an electric bell. This arm strikes against the plate, which releases whichever of the two buttons in the switch may be depressed.

As will be observed, the transformer coil provided has five terminals. One of these is connected directly with the ground, the other leads to the central secondary distributing brush of the timer-distributor. Of the three primary leads, one goes to the switch, one to the wire leading from the storage battery to the timer, and one directly to a terminal on the timer. The switch is provided with three buttons, the one marked B being depressed to start the engine, as the ignition current is then drawn from the storage battery. After the engine has been started the button marked M is pressed in, this taking the current directly from the generator. To interrupt ignition the button "off" is pressed in, this releasing whichever of the buttons, B or M, is depressed. Four wires run from the distributor section of the igniter to the spark plug.

One of the most popular of the combined starting, lighting and ignition systems is the Delco, which is shown at Fig. 55. For the present we will concern ourselves merely with discussing the ignition functions of the system, leaving the self-starting and electric-lighting features for consideration later. Current is produced by a one-unit type motor-generator, although the windings of the device when operated as a motor or a generator are entirely separate. The ignition current is obtained either from a orage battery, which is kept in a state of charge by the generaor from a set of dry cells which are carried for reserve igniThe ignition system consists of a one-unit non-vibrator coil,

sometimes attached to the top of the motor generator, though it may be placed at any convenient part of the car, and a dual automatic distributor and timer usually included as a part of the device as shown. When ignition current is supplied from the lighting circuit the current passes from the storage battery through a switch and out to the low-tension winding of the coil, from whence it passes to the timer and from there to the frame, where it is grounded. The high-tension current generated in the coil runs to the distributor, where it is switched to the spark plug in the different cylinders in turn.

The essential elements of any electrical ignition system, either high or low tension, are: First, a simple and practical method of current production; second, suitable timing apparatus, to cause the spark to occur at the right point in the cycle of engine action; third, suitable wiring and other apparatus to convey the current produced by the generator to the sparking member in the cylinder. The important part the storage battery plays in the gasoline automobile can be readily understood by the reader.

Storage Battery for Starting Automobile Motors.-One of the most recent applications of the storage battery is in starting gasoline engines used in automobiles. The storage battery has made the old hand crank obsolete, and has provided a convenient lighting system as well as a positive motor-starting means. The parts of a two-unit starting and lighting system are shown at Fig. 56. This system is sometimes called a "three-unit" system, on account of having a source of independent current supply for ignition purposes. As will be observed, the generator is driven from the motor crankshaft by silent chain connections, one of the terminals passing through the cut-out device and to the storage battery, the other terminal running directly to the storage-battery terminal, having a short by-pass or shunt wire attached to the cut-out. All the time that the engine is running the generator is delivering electricity to the storage battery.

It will be observed that the storage battery is also coupled to the lighting circuits, which are shown in a group at the right of the illustration, and to the electric-starting motor as indicated. One of the storage battery terminals is joined directly to the switch