Practical Organ Building

by W. E. Dickson

We hope we have said quite enough in former pages of roller boards and backfalls to enable any intelligent reader to devise for himself the double action of such an organ. An inspection of Figs. 37, 38, and 39 may suggest ideas to him. An essential point is that everything should be within reach if defects should require attention; and access to the back as well as to the front of such an organ is indispensable.

A word about the borrowing. It is plainly not enough to groove the two channels of each note together in the bass, as in the case of a single manual. If this were done the wind would fill the whole of the two channels upon lowering a key in the bass octave of either manual, and all the stops of which the sliders happened to be drawn at the time would speak together. Thus our purpose of borrowing one particular stop would be defeated. We must effect it thus: the twin sliders will be closely contiguous, and will only be separated by short pins of brass or iron let into the table, to prevent the friction of actual contact. Thus the two holes which are to be brought into connection are near to each other, and the communicating groove will be short. If this is cut in the upper board itself it must be neatly executed, and the bottom of the groove must be level and smooth. Over each of the two holes within the groove so cut must be placed a valve, consisting of a small piece of pallet leather covering the hole completely, and rising with complete freedom by a hinge along its edge, like the clacks of the bellows. Each pair of holes being furnished with these valves the grooves are roofed in and the pipes planted, as described in earlier pages of this book. On lowering one of the keys the wind will affect the borrowed pipe only, since the little valve will stop the twin hole and prevent the flow of air through it into the channel. If the key corresponding to the same note be pressed down on both manuals, then both the little valves will be blown open by the wind; but if all the channels, grooves, and holes be of ample size, so that there is no throttling of the wind, the speech of the pipe will be entirely unaltered, since it will only receive a given quantity of wind through the perforation in its foot, and this wind will be of the same weight or pressure as before.

The borrowing grooves may be cut in the under surface of a separate board, which will then form a roof or cover to the several pairs of valves arranged over the holes on the upper surface of the sound-board itself. Or this borrowing-board may be put together with bars, cheeks, and an upper table like a light sound-board. The essential point is that all the openings be of ample size, and that the valves fly open widely at the slightest breath of wind, and close the holes as promptly when the wind is withdrawn. If due attention is given to all this no failure need be anticipated with the borrowed basses.

We have proposed the lower key-board as "Manual I.," in accordance with the German usage, and because that arrangement will facilitate some of our mechanism, for instance, the pulling down by the pedals of the bass notes. But lovers of old English organs, among whom we must reckon ourselves, may prefer to make Manual I. the upper manual of the two. A beautiful instrument of this class, built by the late J. C. Bishop, stands in the chapel of Jesus College, Cambridge, and was the gift of an accomplished amateur, whose performances on it are still remembered.[4] The same gentleman was the possessor of a chamber organ of exquisite tone by Bernhard Schmidt, of such remarkable composition that it merits description here. The lower manual, or Choir, had three stops, an Open Diapason, a Stopped Diapason, and a Principal, all made of oak, and of extreme delicacy and beauty. The upper manual, or Great, had likewise three stops, all metal, namely, Stopped Flute, Fifteenth, and Mixture of two ranks (19th and 22nd in the bass, 12th and 17th in the treble). The Stopped Diapason could also be played upon this manual by borrowing. A coupler united the lower to the upper at pleasure, and then the "Full Organ" was produced upon the upper manual with an astonishing effect of sprightliness and brightness. Such an organ as this, with some changes (its key-boards were very antiquated, and so high from the ground that the player was perforce erect), might afford an admirable model for imitation.

[4] The late Sir John Sutton, Bart., author of "A Short Account of Organs built in England from the Reign of King Charles II. to the Present Time." Masters, 1847.

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.