Читать книгу The Recent Revolution in Organ Building - George Laing Miller - Страница 14

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Just as we no longer see four men tugging at the steering wheel of an ocean steamer, the intervention of the steam steering gear rendering the use of so much physical force unnecessary, so it now occurred to an organ-builder in the city of Bath, England, named Charles Spachman Barker,[1] to enlist the force of the organ wind itself to overcome the resistance of the pallets in the wind-chest. This contrivance is known as the pneumatic lever, and consists of a toy bellows about nine inches long, inserted in the middle of the key action. The exertion of depressing the key is now reduced to the small amount of force required to open a valve, half an inch in width, which admits wind to the bellows. The bellows, being expanded by the wind, pulls down the pallet in the wind-chest; the bellows does all the hard work. The drawing on the next page, which shows the lever as improved by the eminent English organ-builder, Henry Willis, shows the cycle of operation.

When either the finger or foot is pressed upon a key connected with k, the outer end of the back-fall gg is pulled down, which opens the pallet p. The compressed air in a then rushes through the groove bb into the bellows cc, which rises and lifts with it all the action attached to it by l. As the top of the bellows cc rises, it lifts up the throttle-valve d (regulated by the wire m) which prevents the ingress of any more compressed air by bb. But the action of the key on gg, which opened the pallet p, also allowed the double-acting waste-valve e to close, and the tape f hangs loose. The compressed air, therefore, as it is admitted through bb cannot escape, but on the other hand when the key releases the outer end of g, and lets it rise up again, the tape f becomes tightened and opens the waste-valve, the bellows cc then drops into its closed position.