In the published literature this stop is mentioned only by Sumner, who says: If [Contrabass] could replace the rolling �open wood� of the English cathedral organ of a generation ago, an increase in the musical potentialities of the instrument would result. Alastair Disley kindly provided us with the following description: An Open Wood is a flue pipe of large scale and rectangular wooden construction, usually found on the pedal organs of mid 19th to mid 20th century instruments. To understand its existance, one must look at the development of the English pedal organ. Prior to adoption of the German model, English organs had almost no independent pedal departments, instead taking their manuals down to GG and providing pull-down pedals. Where pedals had any stops of their own, it would be large scale and unison pitch to emphasise the bass. These went down to 12' GG. So when the German model was adopted in the 19th century, with its CC compass manuals and larger pedal, it was a natural step to complete this large scale "Pedal Pipes" stop to 16', and it continued to provide a massive bass to underpin the ensemble. This continued around the turn of the century, where the Open Wood was joined by its Bourdon companion. This pair make up many a British pedal department, often with octave extensions. They were nicknamed Big Boom and Little Boom, and are often both of vast scale. However, they take up a huge amount of space, and since the Organ Reform Movement, independent pedal departments have often displaced these leviathans. Having said that, in large buildings, they make a grand underpinning of the principal chorus, and in their 32' incarnations they are the sine qui non of the English Cathedral Organ. Wind pressure at the feet of these monsters is often remarkably small - often under 2". Although sometimes described as an Open Diapason (wood), the vast scale makes the Open Wood much more like a large scale open flute in tone. The stop is almost exclusively found on the pedals.
Osiris contains fifty examples of Open Wood at 16' pitch, four at 8', and two at 32'. No examples are known of Pedal Open Wood, which is mentioned only by Maclean. Contributions welcome.