97 



ORGAN, CONSTRUCTION OP. 



ORGAN, CONSTRUCTION OF. 



to the length, thickness, and elasticity of the tongue. This form of 

 reed pipe is the basis of all the others, their differences being more in 

 shape than in principle. There is however a distinction between the 

 free reed and the beating reed, aa explained below. [See also HARMO- 

 NIUM.] When speaking of the lengths of pipes, it is generally with 

 reference to tuning or pitch c, which is one foot long; and all c'i 

 below are doubled as we go from 1 to 2, 2 to 4, 4 to 8, 8 to 16, and 16 

 to 32 ; the last, although little used in this country, gives the highest 

 rank to organs. 



SPZAKIXG LEXOTHS ASD SEMIDIAMETERS or STOPS. 



8-foot 

 pipe. 



4-foot 

 pipe. 



2-foot 

 pipe. 



1-foot 

 pipe. 



Centre to the abore Semidimmetcrs, which are real 

 dimensions. This centre most he J an inch below 

 the firnt dot. 



This Table shown the relative lengths and diameters of the open 

 diapafm, the principal, and the fifteenth ttopt, as high as c above 

 middle c. 



Quint* , twdfiht, and mqmuUenu, all take the sizes and lengths of 

 their proper tone* hi the open diapason. Trumpet and Oboe ttopt, 

 being what are called uniton ttopi, also take their lengths from the open 

 diapaton. The clarion, an octave stop, is measured by the principal. 

 The bells of all reed-pipes should be as large as their places in the organ 

 will admit of. 



Middle c in the dtdcuma is an inch and a quarter in diameter, and 

 about two feet two inches long. A large size stop-diapason is seldom 

 pure and musical. An inch and eighth wide and an inch and three- 

 eighths deep, with thirteen inches in length, is a good scale for a middle 

 ttop-diapatoH pipe in wood. Scales may be taken of larger or smaller 

 dimensions, if desired, in which case the larger must be shorter and 

 the smaller must be longer. Where stops are repeated, two or three of 

 the same name, it is thought better to have them of different diameters, 

 from an opinion that two or more unison-pipes of the same diameter 

 affect the car only as one pipe. There is something in this opinion, but 

 how much we will not venture to determine. 



Fi;i. 5 is a section of a tovnd-ltoard, showing some part of the 

 mechanism. A is the rack-board, by which the pipes are held in upright 

 position ; i> shows the ends of the slides ; c, that part of the sound- 

 board which contains the cliannrU for conveying the wind to the pipes ; 

 D, the pallet or valve which is opened by the finger of the organist, 

 through the key, the lever, the pull-doicn, and the roller (see Fig. 7) ; 

 z is the spring which keeps the pallet in its place when not in use ; r is 



ABTS Ajn> SCI. DIV. VOL. VI. 



the putt-down, having a small screw and a leather button at one end, 

 and a piece of hard bell-wire at the other ; the former is fixed to the 



Fig. 6, 



lever, and the latter to the arm of the rotter ; o is merely one end of the 

 roller-board. 

 Fig. 6 represents a draw-stop, a trundle, and a lever, all of which are 



Fig. 6. 



used by the organist in changing a stop or slide ; A is the draw-stop ; 

 B is the trundle ; c is the lerer ; D is the slide. The draw-stop is linked 

 to the trundle at E, 4he trundle is linked to the lever at F, and the 

 lever is fitted to the slide at o. Their centres are all at H. In con- 

 nection with the above, there are also pedals called composition pedals, 

 three, four, and five to an organ. 

 fig. 1 represents certain small parts of the action. A is the wire by 



which the pallet is opened ; B is the pull-down attached to it; c is the 

 pallet-end of the roller, with its fixing to the board ; D is an end view 



B 



