one third of the piston-stroke from its base. The piston in its upward movement draws in a charge of the mixed gases during this lower third of its stroke, and they are then ignited by the jet, the remaining two thirds of the stroke being completed by the impulse due to their expansion. The atmospheric pressure and the fly-wheel carry the piston through its return-stroke, when the above motions are repeated. The supply of gas, both to the cylinder and the ignition-jets, is regulated by the pinch-cocks on the base of the machine, to the left. Before using, the machine is heated somewhat by a small burner placed below the cylinder. In the man-power machine the consumption of gas is eleven and a half feet an hour, which is a better result than is obtained with any other heat-engine of such low power. The motor seems to be in every way adapted to use in the household, and is probably as simple and perhaps as economical a heat-engine as can be made for the purpose.
The burning of a combustible mixture gradually, as is done in the Simon engine, was first successfully accomplished in the machine invented by Mr. George B. Brayton, and known in the market as the Ready Motor or Hydrocarbon engine. When first introduced, a dilute mixture of gas and air was employed, but in those now made the vapor of petroleum is substituted for the gas, with the advantage of a more satisfactory operation and a reduced cost of running. The working cylinder is surrounded by a water-jacket, and is placed upright in a substantial frame. It is open to the atmosphere below, the oil and air being supplied at the top. The oil is contained in a tank of from five to ten gallons' capacity, and is delivered to the engine by a small pump. Air is compressed by an air-pump in reservoirs, at the base of the machine, from which it is supplied to the cylinder. Only one of these reservoirs is used at a time, the other being kept charged so as to furnish an air-pressure with which to start the machine. The burner, by means of which the oil is introduced in the proper form into the cylinder and ignited, constitutes the main feature of the machine, and is at once simple and ingenious. It consists of a small chamber in the head of the cylinder, lined with a strip of felt against which the oil and a jet of air are delivered. The felt becomes saturated with oil, which the air-blast, passing through, carries in the form of a spray against the sheets of perforated metal and wire gauze which separate this chamber from the cylinder. Another and larger blast of air, in passing through the gauze, becomes carburetted by the petroleum vapor, and, entering the cylinder, is ignited by a jet placed immediately below the sheets of gauze. The jet remains constantly lit, and is prevented from retreating into the chamber above by the wire gauze. By simple mechanism the supply of air is cut off, when a part of the stroke has been made, and the combustion of the vapor ceases, the expanding products of combustion carrying the piston the remainder of the stroke. As the cut-off can be made at any point of the stroke, and
