ORGAN 



ORGAN 



THE ORGAN AND ITS MECHANISM 



B. O. Bnlrntow. Mui D.. F.R.O.O.. OrgnnUt ot York Mintr 



cluptdta continue urtuies on the mutual instruments of 

 tmf>vt!ace ; tf. Flute ; Pianoforte ; Violin, etc. See alto Har- 

 mony ; Music ; and biographies of Bridge and other leading orfanittt 



The organ is the largest and 

 moat powerful of musical instru- 

 ments. It has the advantage of 

 many tone qualities, but the dis- 

 advantages of an unsensitivr touch 

 ami the fact that all expression is 

 olituincd from it by mechanical 

 means. It has anything from one 

 to tivc keyboards or manuals, a 

 pedal keyboard, and numbers of 

 st !-. in large organs more than a 

 liun.lred. The draw-knobs con- 

 trolling the stops are arranged in 

 \crtirul rows on both sides of the 

 manuals, and there are various 

 Ties to assist in the man- 

 ipulation of the draw-knobs. 



A speaking-stop consists of a 

 pipe of the same timbre for every 

 note on the keyboard, 61 pipes on 

 an organ of full compass CC to 

 o'". The pitch of the pedal key- 

 board is an octave below that of 

 the manuals. The pedal keys are 

 of wood and very large; the com- 

 pass is from CCC to f, sounding 

 an octave lower than the lowest 

 note on keyboards. There are 

 other draw-knobs called couplers, 

 controlling appliances for coupling 

 the manuals to the pedals and to 

 each other, so that keys depressed 

 on one keyboard sound the 

 corresponding notes or octaves on 

 that to which they are coupled. 

 The length of a pipe governs its 

 pitch, and the shape its quality. 



A pipe sounding CC is approxi- 

 mately 8 ft. in length, and a stop 

 sounding the notes as printed is 

 known as an 8 ft. stop. Those of 

 16 ft. sound an octave below what 

 is printed ; those of 4 ft. an octave 

 above. The 8 ft. stops give the in- 

 strument its breadth and dignity ; 

 they out-number those of any other 

 single pitch. 16 ft. stops are chiefly 

 found on the pedal keyboard ; they 

 fulfil much the same functions as 

 the double basses in the orchestra. 

 32 ft. stops are included in large 

 organs. The 4 ft. and 2 ft. stops 

 add brilliance. 



Varieties o! Pipes 



Pipes are divided into tw o main 

 groups, flues and reeds. The 

 flues, diapasons, flutes, etc., made 

 of wood or metal, sound on the 

 same principle as a tin whistle. 

 The front pipes of an organ belong 

 to this group. The air in a reed 

 pipe, usually made of metal, is put 

 in vibration by wind forced be- 

 tween a semi-cylindrical tube and 

 a brass tongue covering its open 

 side ; this is placed in the foot of 

 the pipe. A flue pipe with its 

 upper end closed by a stopper 



sound* an octave lower than an 

 open pipe of the name length. 

 Harmonic pipes, reed or flue, are 

 o treated as to sound th< 



liuim-m.'. that is, an octave lu-ti'-r 

 than an ordinary open pipe of tin- 

 same length. 



The manuals each have separate 

 functions. The most important, 

 Great Organ, contains the loud 

 stops, flues, and reeds, of all 

 I'lti-hc.s. The pipes of that Kitu.it- ! 

 immediately above, Swell Organ, 

 are enclosed in a wooden b< 

 side of which consists of Venetian 

 shutters, opened and closed by 

 means of a pedal, thus creating a 

 crescendo and diminuendo. It 

 has stops of similar variety and as 

 comprehensive in character as the 

 Great Organ. That situated near- 

 est the player, when there are 

 three, Choir Organ, has assigned 

 to it stops of soft and delicate 

 quality. The fourth manual, solo 

 organ, contains the stops imitating 

 orchestral instruments strings, 

 wood-wind, and brass. Occasion- 

 ally organs have a fifth manual, 

 Echo Organ, the pipes of which 

 are placed at a distance from the 

 rest of the instrument. The choir, 

 solo, and echo organs are often 

 enclosed in swell boxes. This 

 description of the manuals up- 

 olles only to British organs. 

 Mechanical Wind Supply 



Only small organs can be blown 

 by hand : the demand for different 

 wind pressures and the use of 

 pneumatic action make it impera- 

 tive that larger organs should have 

 some form of motor combustion, 

 hydraulic, or electric to supply 

 wind. Electric motors are the 

 cheapest and best. 



In the llth century men were 

 already acquainted with the art 

 of manipulating the opening at 

 the lower end of the pipe in 

 order to alter its quality and 

 power of tone. At this time also 

 the key was improved. Under each 

 pipe a valve or pallet was placed, 

 held closed by a spring. A cord 

 joined the valve to the key, which, 

 when depressed, opened the valve 

 and allowed wind to pass into the 

 pipe. Afterwards the cord was 

 superseded by a system of wooden 

 levers, or trackers, and keys, from 

 being four inches from centre to 

 centre, gradually assumed their 

 modern proportions. 



In the 15th century organs were 

 made with more than one manual ; 

 the pedal keyboard was added ; 

 draw-knobs came into use, but in 



very primitive form. It WM not 

 until the 16th cent. that the present 

 system of stop control WM initi- 

 ated. Sliders were re-introduced, 

 but this time they ran lengthwise to 

 the rank of pipes, above the pallet*, 

 and had M many holes M there 

 were pipes in the rank. Draw- 

 knobs were placed at the sides of 

 the manuals, and, when these were 

 drawn, levers moved th<- li<l<-ri 

 until t he holes came under the pipes. 



Afi.-r the invention of the swell, 

 by Jordan in 1712, no important 

 innovation is found until the 10th 

 i-ntiiry. The invention of com- 

 position pedals by Bishop, in 1800, 

 revolutionised stop control. These 

 are iron pedals placed above the 

 pedal kcyloiinl. When depressed 

 they draw certain stops and take in 

 others, each pedal having a fixed 

 combination of stops. The size to 

 which organs had now grown and 

 the demand for the performance of 

 rapid and difficult passages made it 

 necessary to find some improve- 

 ment upon the heavy and noisy 

 tracker Key mechanism. This was 

 first achieved by pneumatic lever 

 action discovered by Barker in 1832. 

 Pneumatic Action 



The keys, on being depressed, 

 operated valves, admitting com- 

 pressed air from a wind reservoir to 

 V-shaped motor bellows. One side 

 of these was fixed, the other ex- 

 panded, and to the movable side 

 was attached the tracker action. 

 This lightened the touch enor- 

 mously, but was slow in attack and 

 release, and the clattering trackers 

 were still in evidence. Tubular 

 pneumatic action, the work of 

 Moitessier, in 1835, largely deve- 

 loped by Henry Willis and success- 

 fully applied to the organ in S. 

 Paul's Cathedral in 1 874, eventually 

 overcame these difficulties. In this 

 action the key operates a valve, 

 admitting compressed air to tubes 

 which transmit the power to other 

 valves moving the pallets. A still 

 prompter action is electro-pneu- 

 matic, where electric current con- 

 veyed through small wires takes 

 the place of the tubes. The depres- 

 sion of the key simply closes an 

 electric circuit operating magneto 

 which, by means of pneumatic 

 valves, open the pallets. 



Never quite reliable until the 

 close of the 19th century, it is now 

 used by all the principal builders 

 where organs, or parts of them, are 

 at a great distance from the key- 

 boards. Pistons are ivory buttons 

 placed just underneath the man- 

 uals ; they have the same functions 

 as composition pedals. Either 

 tubular or electro-pneumatic ac- 

 tion is now applied to the stop 

 action, composition pedals, and pis- 

 tons. With adjustable pistons the 



