HARMONICS AND ORGAN PIPES of hard wood or metal of various shapes is fastened across the mouth. It is called a beard and performs the same function for a wood stop that a harmonic bridge does for metal pipes. The Fren Harmonique ( first used in organs of French design) also performs the same function as the harmonic by Dan Barton, Organ Builder bridge except it is adjustable and can be 1 2 (CONCLUSION) 'Fren Harmonique' Bridge used on both wood and metal pipes d' Amore pipe at tenor showing an un­ There are two ways of producing har­ which have no ears. It consists of a thin usually elaborate bridge: 1 is front view, 2 is monics in flue pipes, raising the pres­ brass plate with the bridge mounted at an inside view of the same pipe. A and B rep­ resent structure of bridge, C bottom attach­ sure and the use of a harmonic bridge. one end. The plate is screwed to the ment, and D adiustable attachment. By the use of pressure the voicer first front of the pipes. The screws pass The is rated as having the voices the pipe to produce only the fun­ through slots allowing an up-and-down nearest to a true orchestral tone of any damental tone on a pressure lower than organ stop. The tone consists of the will be used in the organ. An example prime tone and the second, fourth and is a pipe voiced on 5" pressure, giving sixth harmonics. only the fundamental tone, will have a A column of air which is narrow in harmonic development when sounded proportion to its length will produce a on 7" or higher pressure. larger and stronger range of harmonics The harmonic bridge is cylindrical in than a wider column. An example is the shape. The length and diameter vary small scale strings in theatre-type organs. with the pitch of the pipe; other factors There are exceptions to all rules. The concerning the size are the dimension flute tone has no audible harmonics, but of the mouth, the wind pressure and the Wooden form of at tenor C. 1 is detail they can be induced as in the harmonic character of the tone required. The po­ of harmonic bridge (frein harmonic _ue), 2 is front view, and 3 is interior, all of same pine. flute. The barrel is double length from sition of the bridge in relation to the middle C up, with a small hole bored mouth and wind stream is a very exact­ adjustment, and by adjusting the upper halfway down the barrel. The hole kills ing procedure. The voicer must have a screw it has an in -and -out adjustment the , preventing the pipe from fine sense of tonal quality and a delicate to adjust the proper distance from the speaking the pitch of its total length. A ear. When the proper position is at­ mouth. The fact that the organ tuner harmonic development is made in the tained the bridge is made permanent or finisher, as most prefer to be called, upper half of the barrel. The harmonic by soldering or driving brads or screws needs only a screwdriver to change or flute speaks its prime tone and the first through the ears to hold it in position. sometimes destroy the exacting work of harmonic or very distinctly. Large It can be placed so the pipe will the voicer makes the Fren Harmonique scale diapasons with narrow and high­ its sub-octave as well as its prime tone a very unpopular part of an , cut mouths have no audible harmonics; or it can be placed so the pipe will at least to the voicer. they are used as a foundation stop in sound one or more or a complete struc­ There are two types of reeds, the both classic and theatre-type unit organs. ture of upper partials. The movement closed reed, also called beating or strik­ A small scale diapason with a wider and of the wind stream against the bridge ing reed, is used in pipe organs to cause lower-cut mouth and fitted with a beard intensifies and increases the harmonic harmonics in the resonator. With closed has a harmonic development. This com­ development. The pipe is first voiced to reeds the tongue beats against a metal bines the diapason and string tones; such speak only the prime tone, then the plate alternately opening and covering a stop, used in classic organs, is the Vio­ bridge is added. a hole cut in the plate or shallot. Free lone, or . On wood pipes of string tone a strip reeds are a metal tongue which vibrates It is hoped that this discussion of the inside a rectangular opening without mysteries of harmonics will increase touching its sides, as on a reed organ readers' understanding in areas where or harmonica. It is used in some classic available knowledge is often stated in organ reed pipes. terms so technical that the average organ In flue pipes, the mouths cre­ enthusiast finds the going rough. I have ates the tonal quality. In reed pipes, the tried to "humanize" the subject through shape and size of the resonator deter­ my approach because, after all, organ mines the tone quality. pipes have some very human qualities; they have bodies, faces, teeth, mouths, Orchestral String "Double Brass" in wood form at CCC. 1 is front view, 2 is an interior view, 3 tongues, lips, ears, throats, caps, feet, is detail of harmonic bridge, and 4 is detail boots, toes - and harmonics. of mouth area where sound are origi­ (Illustrations are from "Dictionary of Pipe Or­ nated . A is lower lip, B is the bridge, C is gan Stops" by Stevens Irwin (ATOE), published block, D is upper lip. E is used to show ends of by G. Schirmer, Inc.) • bridge for attachment to pipe, and F is har­ monic-creating ridge on bridge . -Dan Barton, Oshkosh 5 december 1967 32