Practical Organ Building

by W. E. Dickson

Fig. 32.

But this is taking no account of the fact that the pipes are not planted in an unbroken chromatic series from bass to treble. In the arrangement shown in Fig. 5 (and in its reverse or opposite plan) it is plain that our simple backfalls would fail us; while in Fig. 6 some of the bass pipes are planted to the right of the player, equally out of reach.

Here we resort, then, to rollers. Fig. 33 shows a single roller, in which i k is the roller, turning on pivots in studs, and having arms, l, m, of wood or of iron, projecting from it. The sticker from the key-tail pushes up the arm l when the key is depressed; the roller turns on its pivots, and the arm m pushes up the tail of the backfall by another sticker, the pallet being thus opened as before; and it is plain that by arranging a set of rollers on a board, as in Fig. 31, we may act with ease upon pallets to the right and left which could not be reached in any other way.

Fig. 33.

The roller-board as here described is placed above the key-board, with action by stickers; but it might be as easily placed immediately under the wind-chest, with action by trackers. In this latter case, the key-tail will push up the end of the backfall, the other end of which will draw down a roller arm by means of a tracker; the other arm of the roller will be hooked to the pull-down of the pallet by means of another tracker. If so placed, room must of course be left for the roller-boards by fixing the wind-chest at a sufficient height above the backfalls. Figs. 34 and 35 show, sufficiently for our purpose, but without any pretension to exactness of detail, the two positions of the roller-board, and it is easy to see that by reversing the backfalls, and in Fig. 35 the roller-board also, we can act upon a back wind-chest.

Fig. 34.

Probably the reader has already surmised that the notches in the bridge are by no means necessarily parallel to each other, or, in other words, that the backfalls themselves are not parallel. The left-hand pipes, as shown in Fig. 6, are reached by cutting the notches in the bridge askew, so that while one end of the backfall is over the key-tail, the other may be under the pull-down; and as this applies to the whole set of backfalls, except those connected with the rollers, the whole of the notches will be cut at varying angles to the central line or axis, and the complete set of backfalls, when put in their places, will present a fan-shaped plan. Hence it is sometimes called a "fan-frame."