1851 Great Exhibition: Official Catalogue: Class X.: Henry Willis
209. WILLIS, HENRY, 18 Manchester Street, Gray's Inn Road — Designer and Manufacturer.
An organ, with three rows of keys, and two octaves and a fifth of pedals. This instrument is built upon the German plan, viz., 8 feet manuals, and 32 feet pedals; it contains 77 stops, nearly 4,500 pipes, the largest being CCCC 32 feet, the smallest C 3/8 of an inch. The great and swell organs are played by means of the pneumatic lever, applied vertically, and worked without the aid of additional wind pressure. In the choir and pedal organs are introduced two newly-invented patent valves, over which the pressure of the air has little influence; also a patent movement in connection with a compound application of the pneumatic lever, which brings the instrument entirely under the performer's command. The mechanism includes several new arrangements, and in the various bellows there are five different pressures of air. This organ is represented as it stands in the Exhibition.
[The superiority of the German plan for building organs chiefly consists in its preserving a balance of power amongst its various masses. The attention of our native builders has been profitably directed to this essential point for some time past, and we hope the time will soon come when an instrument will not be considered complete without a commensurate pedal organ.— H. E. D.]
An organ, consisting of a swell, with 22 stops. A choir organ of 14 stops.
A great organ of 20 stops.
A pedal organ of 14 stops, and several coupling stops, exhibiting various improvements, including an extensive use of the "pneumatic lever."
[Organs on the pneumatic principle were first introduced into churches by Pope Vitalianus, anno 666. Coupling-stops are used for combining two or more keyboards, so that playing on one produces the effect of both.—H. E. D.]