Our thanks to Gregory Cooke, Cortland, New York, for sending in this excerpt from The History of the Centennial Exhibition by Jas. D. McCabe, 1876. The book commemorates the six-month long Centennial Exhibition held in Philadelphia that year, the first official World’s Fair in the U.S.
“From the gallery one looked down upon a busy scene. The great engine in the centre drove several miles of shafting and belting, and the hall resounded with the hum and click of the machinery in motion.
“No fires or furnaces were allowed in the hall. The boilers of the great Corliss engine were placed in a separate building on the south side of the hall, and steam was introduced into the hall by a service of pipes.
“The motive power for all the machinery in motion in this vast hall was a double-acting duplex vertical engine, erected by Mr. George H. Corliss, of Providence, Rhode Island, its inventor. It stood in the centre of the hall, and was built upon a platform 56 feet in diameter, and 3-1/2 feet above the floor of the hall. The engine rose to a height of 40 feet above the platform, and was the most conspicuous object in the hall.
“It had cylinders of 44 inches in diameter and 10 feet stroke, the peculiar variable cut-off arrangement being actuated by the governor, as common in the Corliss engines. Between the vertical engines was a flywheel of 56 tons weight, 30 feet in diameter and 24-inch face; it made 36 revolutions per minute, the rate being kept equal by means of the governor cut-off, which immediately responded to any change in duty, owing to the throwing off or on of machines either singly or embraced in a whole section of the building. The tubular boilers were 20 in number, in a separate building, and each represented a nominal power of 70 horses, the work of the engine at 60 pounds pressure being about 1,400 horsepower. The flywheel had cogs on its periphery, which matched with cogs on a pinion which rotated a line of underground shafting, and this by means of mitre-gearing rotated other underground shafts, so that motion was communicated to eight points in the ground-plan at the transept, at which were pulleys from which belts rose through the floor and thence passed around primary pulleys on the eight principal lines of shafting, which reached from the transept to the extremities of the east and west ends of the building. The sunk shafting, its mitre-gears, pillow-blocks and pulleys, weighed 200 tons.
“The work on the engine was completed on the 10th of April, the day promised by its inventor, and the entire cost of its construction — $200,000 — was borne by Mr. Corliss.”