Let us add that if pedal notes of 16-feet tone are added to an organ of this class, namely of two manuals, Great and Choir, only twelve large pipes will be necessary, even though the compass of the pedal-board be of thirty notes complete. This great economy of space and outlay will be secured thus: 1st, by making the pedals pull down on the chief manual throughout their whole extent as before; 2nd, by adapting the twelve deep pipes to the lower octave of the pedals, and by making their upper octave and a half pull down upon the lowest keys of the second manual. A moment's reflection will show that the 16-feet tone is thus obtained throughout the whole compass, and no inconvenience whatever will ensue to the player.
The mode of introducing the large bass pipes, and of pulling down as above, will be described before we conclude this work.
Still desiring to erect a _chamber_ organ, and, therefore, to be chary of space and cost, we must now show how the swell-box may be included in our design.
We shall suppose that the organ has been completed so far as the lower manual is concerned, with all that pertains to it, according to the rules which have now been given at length and in detail. In laying it out we must assume that care has been taken to give increased size to the bellows, and to arrange the frame for the reception of a second sound-board.
We feel it due as well to our readers as to ourselves to explain that we confine ourselves in all that follows to a description of work done by ourselves in our own workshop.
We shall place only three stops in our swell, which will have a compass of forty-two notes, from Tenor C to top f. The stops will be a Diapason in wood, partly stopped, and the rest open; a Flute of 4-feet tone in wood, open throughout; and a Gamba of reedy quality, in metal, of 8-feet pitch, but only descending to Fid. G., 3 feet, the remaining notes being grooved to No. 1. This curtailment is greatly to be regretted, but such imperfections are among the objections to the swell-box, which would assume dimensions inconsistent with a _chamber_ organ if an attempt were made to give full compass to its 8-feet stops.
The sound-board for these three stops will be only 2 feet 9 inches in length, and 1 foot in width; but the upper boards must have an ample margin or surplus in both directions to afford support for the box which will rest upon them.