h, into the igniting chamber, g, the requisite amount of gas and air,
the ratchet plate, j, is pushed into such a position by the pawl, j3,
that the flame from the igniting jet, l, passes through one of the slots
or holes, j1, and explodes the charge when opposite j6, which is the
only aperture in the end of the working cylinder (see Fig. 7 and Fig.
2), thus driving the piston on to the end of its forward stroke. The
exhaust valve, Fig. 9, though not exactly of the form shown, is kept
open during the whole of this return stroke by means of the eccentric,
e3, on the shaft working the ratchet, and thus allowing the products of
combustion to escape through the exhaust pipe, i7, in the direction of
the arrow. Between the ratchet disk and the igniting flame a small plate
not shown is affixed to the pipe, its edge being just above the burner
top. The flame is thus not blown out by the inrushing air when the slots
in ratchet plate and valve face are opposite. This ratchet plate or
ignition valve, the most important in any engine, has so very small a
range of motion per revolution of the engine that it cannot get out of
order, and it appears to require no lubrication or attention whatever.
The engines are working very successfully, and their simplicity enables
them to be made at low cost. They cost for gas from 1/2d. to 11/2d. per hour
for the sizes mentioned.

[Illustration: Fig.9.]

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GAS FURNACE FOR BAKING REFRACTORY PRODUCTS.