Mr. Allen had in his shop in Mott Haven an unoccupied second story, in which I had stored our patterns and drawings and drawing implements. Here I established my quarters, and spent my working hours until this second job was finished.
The two [perspective views] of [opposite sides] of the engine, show these changes as they appear externally, and the remaining views show some constructive details.
These [latter] show the exhaust valves transferred to the front side of the engine, and located so as to drain the cylinder, and the admission valves set at different elevations, to accommodate the differential connection, the abandonment of the separate steam-chest, and this chest with the exhaust chambers cast with the cylinder, with openings over the valves; the levers by which the differential movements are given to the admission valves; and the single-link rod, and the gab by which this rod is unhooked, with the method of moving the admission valves by hand.
In place of the levers on the steam rock shaft, I at that time drew cast-iron disks, which being polished and vibrating in place I thought very handsome. They gave me lots of trouble, till I learned enough to get rid of them, the story of which I will tell by and by. The front view shows the admission valve stems balanced by being extended through at the back end, a feature which helped the governor action when high steam pressures were employed, but which was abandoned as unnecessary after I abandoned the disks on the rocker shaft.
First Arrangement of Exhaust Valves.
The first [two] [figures] show the valves in section and the adjustable pressure plate and mode of its adjustment. The closeness of the piston to the head may be observed. I never allowed more than one-eighth inch clearance, and never had a piston touch the head. This was because the connecting-rod maintained a constant length, the wear of the boxes being taken up in the same direction.
These illustrations show the exhaust valves after alteration made several years later in Philadelphia. As first designed by me, these are shown in the foregoing [sectional views]. As will be seen, the exhaust valves lay with their backs towards the cylinder, worked under the pressure of the steam in the cylinder, made four openings for release and exhausted through the cover.
I consented to the change in Philadelphia because this arrangement involved too much waste room, but the change was not satisfactory after all. I had become possessed with the idea that the engine running at high speed needed 50 per cent. more room for exhausting than for admission. This was not the case. I have always regretted that I did not retain this design, and content myself with reducing the exhaust area.
The lightness of the piston in this view will be observed. This was a special design for adapting the engine to be run at 200 revolutions, giving 1200 feet piston travel per minute. The stuffing-box was a freak which was abandoned.