Organ

Unless the action be tubular pneumatic or tracker—both older and non-electrical methods of forming our figurative "chain"— it is customary to detach the console and place it at some distance from the organ, connection being made by electric cables. For descriptions of pneumatic and purely mechanical actions, see G. A. Audsley's The Art of Organ Building.

But to revert to the key action "chain." Every manual and pedal key in the console has a thin bar of copper attached to it, so that when pressed it bridges the gap in the "return" wire and closes the circuit. The stop action "chain," operates on an identi cal principle and need not be further described.

Except the combination piston action, the sole remaining "chain" is the coupler action. This has its beginning and end in the console itself, and is merely a cut-out switch intercepting the 61 key circuits simultaneously. Every new coupler means an extra switch and an extra "return" wire in the key contacts, all "mains" throughout being permanently conjoined with the + terminal. The reader should appreciate, however, that the moving in or moving out of a coupler-switch is a purely local and external process. Although actually performed by means of solenoids or electro pneumatic motors, it might just as well be done by hand, could the organist only reach out to the switchboard at the back of the console.

Controls.

The combination pistons under each manual con trol not individual stops of that manual, but groups of stops. When pressed by the organist's thumb they have the effect of throwing out whatever combination of stops he may have selected, without his having to touch the knobs. The Pedal Organ combi nation pistons are pressed by the right foot of the organist. On luxuriously equipped consoles it has become customary to fit also four or five general pistons, i.e., having a jurisdiction over every stop and coupler in the organ. In an up-to-date console all pistons should be readily adjustable by the player, so that he may set them to operate whatever selections of stops he pleases.

Unit Syste.

Nearly all organs designed for cinematograph theatres are built on what is known as the unit or extension sys tem; and in this respect are to be distinguished from the orthodox type which has been described. The distinction lies in the fact

that whereas an orthodox organ has separate and individual stops for each manual and pedal, a unit organ employs the same rank of pipes again and again at various pitches and (rather mislead ingly) under various names. By way of illustration take the case of a series of four gedeckt stops—bourdon Oft., tibia clausa 8ft., zauberflote 4ft., piccolo 2f t. Under the orthodox system each stop would be a separate rank consisting of 61 pipes, the total number of pipes being 244. Under the unit system there would be one master rank of only 97 gedeckt pipes (eight octaves), and from this rank the four "stops" would be derived at the four different pitches and under the four different names.

The unit system has been mentioned here, because at the heart of it all is the coupler switch just described. What has really happened is that couplers acting at the various pitches have taken the place of independent stops, and the electric wiring has been done for a wholesale adoption of switches instead of draw stop actions. If so many "stops" are to be extracted from one parent rank, a corresponding number of electric switches will be needed, together with an equal number of return wires on each of the key contacts.

At the switch-board is effected also "duplexing," or rendering a stop available on more than one clavier—a necessary facility in the theatre organ and even in the Pedal section of an otherwise "straight" church organ.

Mention may also be made of the "double-touch" device now frequently incorporated in the modern cinematograph or concert hall organ. Its operation is quite simple and may be explained in a word. A clavier having this device is one of which the keys, when played, fall not only to the standard depth of touch, but also—on extra pressure being applied by the finger—another ?4. " or so deeper. The purpose of the second touch is to enable any key to make a second electric contact at the lower level, and so to engage a second circuit when it reaches that point. As a rule this circuit brings into action a powerful solo stop, a coupler or occasionally some "percussion" (e.g., cymbals) ; but in any case it is plain that a clavier so equipped has the potentialities of two claviers in itself.