The Steam Engine and Its Inventors, a Historical Sketch

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1881 edition. Excerpt: ... rest, as was the case in the atmospheric engine, all the valves were thrown open and steam was blown through the engine to expel air from the cylinder, pipes, and condenser, and fill every part with steam. The equilibrium-valve was then closed, the steam and 1 See letter from Watt to Smeaton in 1778, in Farey on the Steam Engine, p. 329, note. exhaust valves being left open. The injection water being admitted into the condenser, the steam in the cylinder was destroyed, and a vacuum produced under the piston, whereupon the steam from the boiler, pressing upon its upper side, carried it to the bottom of the stroke. The steam and exhaust valves were then closed, and the equilibrium-valve was opened, thus allowing the steam to press equally on the upper and under sides of the piston; and the weight of the pump-rods, meeting with no resistance, carried the piston back to the top of the cylinder, the steam that was above it passing to its under side in the meanwhile. The equilibrium-valve was then closed, leaving the engine ready for another stroke, which ensued immediately upon the steam and exhaust valves being again opened. The steam was thus employed twice over, first above, and afterwards under, the piston, as is still the case in the Cornish pumping engine and other single-acting engines at the present day. CHAPTER XIII. Watt's Double-acting Engine, Or Engine Of RevoLution, FOR DRIVING MILL-WORK OF ALL KINDS. Reference has already been made to the attempts on the part of Watt to produce continuous motion round an axis, by means of an engine of the steamwheel class. In this he was unsuccessful. He was fully alive to the boundless field which existed for the application of an engine capable of producing a regular rotatory motion. It had...