1851 Great Exhibition: Official Catalogue: Class X.: George Maydwell H. Holdich
557. HOLDICH, GEORGE MAYDWELL H., 4 Judd Place East, King's Cross—Manufacturer.
Small choir-organ; having a stop, called the "diaocton" which makes every single stop as good as two distinct ones; having, therefore, double the power and variety of an ordinary organ.
[The choir organ, properly so called, is that part of a large organ which is used for accompanying the choir of singers in a church or cathedral, and is softer voiced than the rest of the instrument.—H. E. D.]