The best results have been ob tained from making the engine in the form shown in the perspective view—that is. with two reverser-eyl hiders and two double-acting work ing-cylinders. The reversemlistons are connected and balanced by a walking-beam, as shown on the right, and are reciproented by an over hanging side-lever, which is con nected to the crank-arm by its con necting-rod. The working-pistons are connected by another walking hen in, and drive the engine by menus of a connecting-rod joined to the third arm of the working-side walk ing-beam. A communion ball-governor is used to actuate a by-pass valve. which when open tends to equalize the pressure on opposite sides of the piston, in that way regulating the speed of the engine. Insteml of one outlet from the reversers to the working-cvlinders there arc two, and two for 4-aell of the working-cylinders. Each reverser is (,1111441yd from the -1111. of the reverser-piston to the muter side of the working-piston directly opposite by a pilie without valve-4, and the Ittp of each reverser is connected with the tap of 'the work ing-cylinder diagonally opposite by it suitable pipe: thus; the pressure from each reverser is exerted on the lower side of working-piston directly opposite and on top of the working piston diagonally opposite at the same time, at the proper moments, to produce motion to rotate the wheel. By this arrangement only cooled air comes in contact with the portion of the cylinder where the piston-rings slide, and with the piston-rods and boxes, so that there is no trouble in packing or lubricating.
In the perspective view the reversers are shown on the right with their two furnaces, the walking-beam connecting the two reverser pistons and the overhanging side-lever with its connecting-rod. These working parts are all driven by the crank, as shown. The working
cylinders on the opposite side are not visible in the picture, but their walking-beam and the piston-rods show their position. This walking-beam, as is seen, has a third arm, which is by a connecting-rod joined to the working-side crank-arm, which drives the shaft carrying the fly-wheel. The small air-pump is shown on the eccentric.
In a test of one of these engines, made in March, 1889, by George II. Barrus, the following results were obtained : The average indicated horse-power was 31.18, and the average brake horse-power The amount of gas-house coke used in 10 hours' run, including the wood and coke required to start the fire, beginning with a cold engine, was 1.91 lbs. per indicated horse-power per hour, and 2•98 lbs. per brake horse-power pet• hour. On the same test, for a period of 6+ hours, after the engine had attained its normal conditions of work, the quantity of coke consumed was P54 lbs. per indicated horse-power per hour, and 2.37 lbs. per brake horse-power per hour. The quantity of water which passed through the coolers amounted to an average of 3,612 lbs. per• hour, which is equivalent to i•2 gallons per min. This water was supplied at a temperature of 3G', and discharged at a temperature of 102.8°.
A test with George's Creek Cumberland coal gave a result of 1•62 lbs. of coal per indicated horse-power per hour, and 2.48 lbs. per brake horse-power per hour.
Fig. 4 shows a pair of diagrams taken during these tests. The line at the bottom is the line of atmospheric pressure. The scale of the diagram being 40 lbs. to the in., it is seen that the air is worked between the pressures of about 65 and 45 lbs. per sq. in. The mean effective pressure in No. 1 cylinder is 12.3 lbs., and in No. 2 cylinder• 13 lbs.