Page:A Dictionary of Music and Musicians vol 2.djvu/617

ORGAN.

II. Description. It has been shown in the preceding History of the organ, how that abroad tiers of pipes from nearly the largest in size to the smallest were accumulated on one keyboard before they were assorted and appropriated to different 'departments'; how that in England, on the contrary, little instruments with comparatively few pipes were dignified with the name of 'pair'; and how that an example possessing two manuals, if it also had two cases, was distinguished by the name of a 'double organ.'

Turning from the rules of the past to the custom of the present, it is found that 'an organ' of to-day sometimes consists really of as many as five separate and distinct organs—Great, Swell, Choir, Solo, and Pedal; but all being enclosed in one case, or at any rate brought under the control of one performer, they are spoken of collectively as constituting a single instrument. To describe such an organ completely and in detail would require a volume, which is impossible here, and is besides unnecessary, as the smallest specimen equally with the largest comprises a certain number of necessary parts; namely, (1) the apparatus for collecting thewind, viz. the bellows; (2) the means for distributing the wind, viz. the wind-trunk, the wind-chest, and the soundboard-grooves; (3) the mechanism for playing the organ, viz. the clavier and the key-movement; (4) the mechanism for controlling the use of the tiers of pipes, viz. the drawstop action. To these have to be added the couplers, composition pedals, etc.

1. The Bellows that collect and compress the wind have already been described in vol. i. p. 214. They are shown in the accompanying woodcut occupying their usual position in the lower part of the organ; the reservoir being marked r,r,r,r, and the feeder t,t,t. From the reservoir of the bellows the wind is conducted through a large service-pipe or 'wind-trunk' to the wind-cisterns or wind-chests z,z, where it remains for further use in smaller quantities. The wind-trunk, which could not be conveniently shown in the woodcut, is made either of wood or metal, and traverses the distance between the reservoir and wind-chest by the shortest convenient route. The wind-chest is a substantial box of wood extending the whole length of the soundboard; about equal to it in depth; and about two-thirds its width. In this chest are located the soundboard pallets (d and k), which prevent the wind proceeding any farther, unless one or more of them are drawn down (or opened) by the means next to be noticed.

2. The Key action is the system of mechanism by which the performer is able to draw open the pallets, which are otherwise far beyond his reach. In an action of simple construction this consists of a key (a), sticker (b), roller and tracker (c), communicating with a pull-down (d) attached to the pallet. On pressing down the front end of the key (a) which key works on a metal pin or centre the further end rises, lifting with it the vertical sticker (b). This sticker, lifting the first arm of the horizontal roller, causes the roller partly to revolve. At the opposite end of this roller is a second arm projecting from the back, which consequently descends (c). To this is attached a tracker made to any length necessary to reach from the second roller-arm to the pulldown (d). The course of the motion transmitted by these parts is as follows:—The keytail carries the motion inwards, the sticker carries it upwards; the roller conveys it to the necessary distance right or left, while the tracker again carries it upwards to the pallet. In modern organs of superior construction, small discs of crimson cloth are placed at each end of the sticker, to prevent any rattling between the contiguous parts of the mechanism. A pin passes down from the sticker, through the key-tail, to prevent the former from slipping off the latter. A second one is placed on the top, and passes through an eye in the roller-arm to secure the certain action of the roller. The two studs into which the roller-pins pass to sustain the roller are lined with cloth, or 'bushed,' as it is termed, also to secure silence in action; and the rollers themselves are made of iron tubing, which is more firm and rigid than the old wood rollers, and has the additional advantage of taking much less space.

It is a matter of much importance to lessen the strain on the key-movement just noticed by reducing the resistance at the pallet as much as possible, and thus also relieving the finger of the player from all unnecessary labour and fatigue. For this purpose most builders make use, under certain circumstances, of what are called relief pallets. When wind, in however small quantity, gains admission above a pallet, the wind-pressure ceases by becoming equal all round, and there remains only the elastic resistance of the spring to be overcome. To effect this relief numerous devices have been thought of, as the 'jointed pallet,' in which two or three inches of the fore part move first, and then the remainder, perhaps for nearly a foot in length. There is also the 'double pallet,' in which a small valve is placed on the back of the large one, and opens first, etc., etc. In large organs some builders use relief pallets to obviate the necessity for 'pneumatics,' though the two are sometimes used at the same time.

3. The Draw stop action is a second system of mechanism, by means of which the performer is enabled to draw-out or push-in any slider that lies beneath a separate set of pipes or stop. In the accompanying drawing each separate pipe depicted represents a single member of a different stop [see ], and the slider-ends are the little shaded portions that are shown immediately over the soundboard groove (e,e,e and o,o,o,o). The