Note 161 — Chapter XIII · Watt in Cornwall—Introduction of his Pumping-engines.
Reading edition
“I have seen five of Bonze’s engines,” wrote Watt, “but was far from seeing the wonders promised. They were 60, 63, and 70 inch cylinders. At Dalcoath and Wheal Chance they are said to use each about 130 bushels of coals in the 24 hours, and to make about 6 or 7 strokes per minute, the strokes being under 6 feet each. They are burdened to 6, 6½, and 7 lbs. per inch. One of the 60 inches threw out about two cubic feet of hot water per stroke, heated from 60° to 165°. The 63 inches, with a 5 feet stroke, threw out 1½ cubic foot, heated from 60° to 159°,” and so on with the others.—Watt to Boulton, 25th August, 1777. Boulton MSS.