... cylinder. The exhaust takes place chiefly through a port uncovered when the piston is approaching the end of its stroke. The remaining vapor left in the cylinder is exhausted under the lower edge of the main valve, until cushioning commences, and the steam from both upper and lower ports is discharged into the exhaust box shown in Fig. 2. The speed of the engine is controlled by a centrifugal governor and an equilibrium valve. ... — Scientific American Supplement, No. 481, March 21, 1885 • Various