Sesquialtera

by Colin Jilks

JACK BRYMER was a clarinetist whose relaxed playing style and beguiling tone inspired a generation. How he produced such musical sounds from just a reed and a wooden tube is extraordinary, the technicalities quite bewildering. An organ’s Clarinet pipe is not, in essence, radically different from the real instrument, as it also has a vibrating reed and a tube to contain and amplify its excited column of air. Nevertheless, in comparison with the real thing, under human breath control, it is but a pale undeviating imitation; Gershwin’s Rhapsody in Blue would surely sound quite musically bereft.

English Stopped Diapason

   However, how organ pipes, in their many manifestations, produce their musical notes was a subject raised earlier this year when our Association visited Minster Abbey, on the Isle of Sheppey, to hear and try the 1927 Henry Willis 111 organ. Describing the organ’s specification, I mentioned some of Willis’s more unusual stops in the organ: the Swell Cor de Nuit 8ft, a metal stopped rank, and a Great Flute Triang 8ft, a wooden stop with, as its name suggests, only three sides.

   The speech of stopped pipes seemed to be of particular interest, in many ways more complex than open flue or reed pipes like a clarinet; even Jack Brymer’s consummate skills would have been thwarted by a stopped clarinet.

   Pipe stoppers have a pitch-changing ability, effectively doubling the speaking length of a pipe, making a 4ft pipe sound at 8ft pitch, as well as producing a series of harmonics quite different from those of an open pipe. The Cor de Nuit 8ft used by Henry Willis at Minster is also unusual, as in most cases he preferred a Lieblich Gedeckt, which has the significant difference of having a perforated stopper. A perforated stopper is one with a small hole drilled through its handle, venting the pipe to the outside air.

   It was suggested, by one of our more logically thinking members, that a vented pipe could not possibly speak at 8ft pitch if its stopper was “unsound” with a hole in it. However, the perforated stopper design is widely used in organ pipe voicing, the Lieblich Gedeckt the most common example and, depending on the diameter of the opening, usually about an eighth of an inch at middle “C”, can create a variety of tonal colours. In practice, the larger the perforation, the more the pipe’s fundamental tone is reduced and upper harmonics increased. If taken to extreme the fundamental can almost completely disappear, leaving just vague harmonics, which are unmusical and distorted.

   The perforation in a wooden stopper forms, in effect, a small tube of some two to three inches in length, on a middle ‘C’ size pipe. Metal flute pipes, with “canister” stoppers have metal tubes fitted called “chimneys”, the Chimney Flute an obvious example. The more common English Stopped Diapason 8ft however, is normally of wooden construction with unperforated, fully sealed stoppers. The Pedal Bourdon 16ft is designed in the same way: sealed stoppers producing a full rich fundamental tone without too many overtones.

   Interestingly, the 1695 Renatus Harris organ at St Clement’s Church, Eastcheap, London and Snetzler’s 1760 instrument at the Queen’s Chapel, St James’s Palace both use metal Chimney flutes for their flute ranks, (see illustration). These pipes work well with lower wind pressures, producing colour and character. However, at the Queen’s Chapel when William Hill added a Swell organ in 1869 to complement Snetzler’s 1760 Great Organ, a wooden 8ft flute was used, but with the necessary perforated stoppers, giving a wooden warmth with Lieblich Gedeckt colour and clarity.

   Metal flutes invariably have “tuneable” ears, allowing the stopped top of the pipe, with its venting chimney, to be soldered in place creating a fixed pipe length. Tuneable ears are extra long ears, which can be bent to shade the pipe’s mouth allowing it to be tuned.

   Pipe stoppers have been explored and utilised by organ builders over the centuries, producing organs with their maker’s distinctive character. Interestingly, an harmonic pipe produces a 4ft note from an 8ft pipe, the complete reverse of a stopped pipe, having a small venting hole half way up its body length. This is another intriguing pipe family, but I wonder, what would Jack Brymer have made of it?

Chimney Flute with "tuneable" ears

 

 

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