CHAP, v.] THE ORGAN. 195 



This instrument contains sixty-seven full speaking stops and 

 thirty-one mechanical combinations, in all ninety-eight tone-con- 

 trolling movements, and embraces seven distinct organs, namely, 



Pedal organ 30 notes 



Great organ 



Choir organ . . 



Swell organ 



61 notes 

 Solo organ 



Echo organ . 



Carillon organ (Metal Bells, 4 feet.) . . . 



The motor power which gives wind to this important instrument 

 is an eleven-horse steam-engine, which sets in motion " vertical 

 feeders," for the double purpose of supplying wind at different 

 pressures into special reservoirs, whence it is distributed by a 

 series of wind- trunks into seventeen other reservoirs in connection 

 with the various organs and sound-boards, and also of creating 

 a vacuum in two large vacuum reservoirs, which, by means of a 

 series of independent conveyances, distribute throughout the interior 

 of the instrument the "vacuum pressure" for performing all the 

 mechanical action of the organ namely, drawing the stops and 

 couplers, vacuum pneumatic key action, pedal action, echo action 

 (100 feet distant from key-boards), and carillon action. The great 

 advantage of atmospheric vacuum over compressed air as a motor 

 is, that the one is instantaneous " nature abhors a vacuum " while, 

 from the elasticity of air, the other is slow and uncertain. The 

 vacuum pressure is distributed by means of metal tubes, which 

 ramify from the console in connection with the registers, combination 

 foot-pedals, and combination finger-buttons, couplers, and tremulant 

 action, over the entire instrument, to independent power bellows in 

 connection with the various sliders, &c. By this means the mechanical 

 action of the organ is brought under the control of the performer at 

 the key-boards, who has at command the various changes of registers 

 and " tone colouring " of the entire instrument. The " echo organ," 

 an independent instrument, placed at an elevation of thirty feet, and 

 at a distance of 100 feet from the great organ keys, is actuated by 

 electrical agency, and the mechanical action by " vacuum pressure." 

 Thus the connection between the two organs is simply " vacuum 



o 2 



