CHAP, v.] THE ORGAN. 189 



the front and underneath the sound-board ; this is called -ft wind- 

 chest. We must now show how the wind can pass through this 

 into the pipes above the sound-board. The upper board, besides 

 being pierced with holes to receive the pipes, has also a series of 

 grooves, each of which extends to the pipes of one key. These are 

 separated from each other by parallel bars, called sound-board bars. 

 Through these grooves holes are pierced vertically underneath the 

 pipes of the stop. Lastly, a movable wooden slide, also pierced 

 with holes, is made to pass through each groove ; this is the stop or 



register, CR,C'R',C"R" Now, when the stop is open that is to 



say, when the organist has drawn out the handle which corresponds 

 to the stop he wishes to speak, all the holes of the stop are oppo- 

 site to those of the table and the grooves which answer to the stop. 

 The wind can then reach the aperture of each pipe. In this case it 

 would cause all the pipes of the same stop to speak at the same 

 time, if a special arrangement did not close the passage of the wind 

 in all the pipes which did not precisely correspond to the note or 

 notes which the performer pressed down. " To prevent this, the wind- 

 entrances are first of all closed beneath by movable pieces of wood, 

 s, (Fig. 136) which are kept close by the spring r, which, however, 

 are so adjusted that any one or more of them can be drawn open at 

 pleasure, by means of the ' pull-down ' wire and lever action d, in 

 connection with key-board and wind admitted into the corresponding 



groove These pieces of wood are called sound-board pallets ; 



and from them the openings which they cover are named pallet- 

 holes." l 



The clavier of the organ is similar to that of the piano, with this 

 difference, that the organ, according to size, possesses from one to 

 four claviers. By pressing down a key with the finger, the organist 

 puts into motion, with the assistance of a very simple mechanism 

 called the key movement, the rods d, which open the valves, and 

 thus bring the wind into the grooves of the wind-chest. Besides 

 the keys worked by the hands of the performer, there are pedal 

 claviers which correspond to particular stops, and which are put into 

 motion by the feet. The pedals are exclusively for the bass. 



In conclusion, let us imagine the organist seated in front of the 



1 History of the Organ. Hopkins and Rimbault. 



