Fig. 29. Diaphone in St. Paul's Cathedral, Buffalo, N. Y.
In Fig. 29 will be found an illustration of the Diaphone (or valvular reed) used in the Hope-Jones organ at St. Paul's Cathedral, Buffalo, N. Y.
Upon depressing a key, wind is admitted into the box B. Pressing upon the valve V it causes it to close against its seat in spite of the action of the spring S. This, however, does not take place until a pulse of air has passed into the foot of the pipe P, thereby originating a sound wave which in due time liberates the valve V and allows the spring S to move it off its seat and allow another puff of air to enter the pipe P. By this means the valve V is kept in rapid vibration and a powerful tone is produced from the pipe P. At Middlesborough, Yorkshire, England, Hope-Jones fitted a somewhat similar Diaphone of 16 feet pitch about 1899, but in this case the resonator or pipe was cylindrical in form and measured only 8 feet in length.
In Fig. 30 will be found another type of Diaphone in which the tone is produced through the medium of a number of metal balls, covering a series of holes or openings into the bottom of a resonator or pipe, and admitting intermittent puffs of air.
