cated by the arrows, and mixes with the air which was drawn in by the piston previous to stopping. Part of the air is displaced through the nozzle (8). At first air only passes out in this manner, but after a few seconds a mixture of gas and air is discharged; this mixture lights at the pilot light (6), and burns in the atmosphere more vigorously as the mixture becomes richer. Whenever it is rich enough in gas, which can be readily seen by the colour of the flame or by the characteristic roar made by it, the button (7) is released and the gas inlet shut off, and the cessation of flow allows the flame to strike back through the nozzle (8) into the compression space, and gives the starting impulse.

SCALE 54

FIG. 128.-STARTING DIAGRAM-LANCHESTER

On the return stroke the products of combustion are expelled, on the next forward stroke a charge of gas is drawn in, and on the return stroke (compression stroke) the exhaust valve is held open almost the whole length of the stroke so that sufficient compression is attained to force the remaining charge up through valve (8), lighted by pilot light (6), and before the piston has moved appreciably on its next forward stroke another impulse is given. This is repeated every other revolution until sufficient speed has been attained to start against full compression. In this engine about seven explosions are sufficient. With some sizes one impulse is sufficient to start with the ordinary relieving cam.

One great advantage this starter has is the small amount of shock with starting and successive impulses, for it should

be borne in mind the danger attending a violent impulse when the engine is in a state of rest.

This gear is simplicity itself. It is only a question of pressing a button and the engine does the rest.

The distinguishing feature of the Stockport' self-starter is the automatic firing of the charge in the cylinder as soon as a combustible mixture has been reached.

Fig. 129 (No. 3) is an end elevation of an engine showing the gas connections from the main gas valve box to the inlet on the top of the exhaust valve.

FIG. 130. STOCKPORT' SINGLE-IMPULSE SELF-STARTER

Fig. 130 is a section of the timing valve box and special relief valve for starter. Fig. 131 shows the necessary position of the crank when starting. Fig. 132 is a diagram of a selfstarter and also a diagram from tube ignition, with relieving cam in action, of an engine having a cylinder 18 x 24 inches stroke.

The action is as follows. When the engine is on the impulse stroke, the ignition valve F is full open, and all the other valves closed. The roller on the exhaust lever is put in the position to gear with the relief cam, the gas supply is turned on slightly, so as to fill the gas bag, the escape valve A is opened by placing the small lever B in the notches marked To start,' the valve C' is opened, and the gas coming in under pressure drives out a portion of the air inside the combustion chamber. The only aperture by which the air can escape is in the direction of the arrows by passing the timing valve, and then up the central ignition tube and down the space between inner and outer tubes-which is heated to incandescence-and

SCALEGO

FIG. 132. STARTING DIAGRAM-- STOCKPORT

through the valve A to the atmosphere. In one minute this gas is in sufficient quantity to form an ignitible mixture; the velocity is such that the charge is fired by the ignition tube.

After the engine has made about six explosions (see fig. 132) the valves A', B, and C' must be closed, the gas cock on the gas bag opened full, the exhaust roller on the exhaust lever be moved so that it comes into gear with the main exhaust cam, and the engine will be in full working order.

This starter is simple and effective.

Norris's Starter

Fig. 133 (No. 4) is a facsimile of a diagram taken from an 18 B.H.P. Robey engine fitted with the author's impulse every

K

revolution starter' in 1891. In this arrangement a double set of cams are necessary so that the engine has an impulse every revolution, until sufficient speed has been attained to fire with it from the tube; a pilot light is arranged at the back in close proximity to a small touch-hole.

SCALE 64

FIG. 133.-STARTING DIAGRAM-NORRIS

To start the engine the pilot light is lit, the touch-hole opened, the flywheel moved by hand or lever, and gas and air is drawn in for about one-third of the stroke, the flame is drawn into the cylinder through the touch-hole, and an impulse is given; on the return stroke the products of combustion are expelled. The next forward stroke gas and air is drawn in and another impulse given which is continued until sufficient velocity has been attained to start in the ordinary way. It makes little or no difference if the touch-hole is closed with a spindle or not. The amount of explosion escaping is practically nil.

The complication necessary in using this method prohibits its use.

Clerk-Lanchester High-pressure Starter

In 1891 Mr. Dugald Clerk invented a high-pressure starter, and used the Lanchester igniter in conjunction with it.

Fig. 134 (No. 5) is a sectional elevation of the starter, showing its connection to the combustion chamber of a Robey engine having a cylinder 14 x 21 inches stroke.

Fig. 135 is a diagram taken from this engine, showing a maximum pressure of 200 lbs. above the atmosphere, and an average pressure of 38.3 lbs. per square inch.

To start the engine the check valve A is released and the crank is placed slightly on the firing stroke (say 11⁄2 inch), the pilot