A Dictionary of Music and Musicians/Choir Organ
CHOIR ORGAN. The name given to the small organ which, in cathedral and other churches, used to hang suspended in front and below the larger or Great Organ. It derived its name from its employment to accompany the vocal choir in the chief portions of the Choral Service except the parts marked 'Full,' and the 'Glorias,' which were usually supported by the 'Loud Organ' as it was sometimes called. The choir organ was generally of very sprightly tone however small it might be; one of three stops only not unfrequently consisting of the following combination—Stopped Diapason, Principal, Fifteenth.
Father Smith's choir organ at St. Paul's Cathedral (1694–7), the most complete he ever made, had the following eight stops:—Stopped Diapason (Wood), Principal, Flute (Metal), Gemshorn Twelfth, Fifteenth, Mixture III ranks, Cremona (through), Vox humana (through).
Since the development of the swell organ within the last 50 years, the choir organ has had to yield its position to its more attractive rival the 'second' manual, and now occupies the place of 'third.' It is nevertheless of so useful and convenient a nature, that it cannot be omitted without its absence being constantly felt. [ Chair Organ.]