Practical Organ Building

by W. E. Dickson

The rack-board now being put aside for the present, all the holes may be bored through the upper boards, sliders, and table with bits of various sizes. From what has been said above it will be seen that it is not the sizes of these holes, but of the apertures in the pipe-feet, which regulate the volumes of wind supplied to the pipes; but you will, of course, use bits proportioned to the pipes you have in view. The upper, or treble, holes must not let the little pipes slip into them, nor must the larger holes throttle or check the flow of the wind. In the bass the holes may be as large as the grooves will allow; and if these are narrow, or if there is secondary grooving or conducting, it will be well to cut the round hole at its interior aperture with a sharp chisel into a square or rectangular opening; or to bore two round holes and connect them by taking out the intervening wood. Afterwards, with iron rods of various sizes, heated to redness, scorch all the holes through the three thicknesses of wood, leaving a clear and smooth charred passage for the wind.

We have not yet done with grooving. This seems to be the proper place for pointing out how the use of this system may further assist us in the arrangement of an organ.

Our bass pipes, we have said above, may be planted on holes cut in any part of the covering or roof of their respective secondary channels. It follows readily from this that the secondary groove or channel may be extended or prolonged for the express purpose of locating the pipes in situations convenient for them. Quite apart from any necessity which may exist for supplying a common bass to two or more sliders, we may evidently plant our larger pipes almost where and how we please by cutting grooves in the substance of the upper board, extending from the table beneath to the point where we wish the pipe to be. So long as the holes are of sufficient diameter and the grooves of ample dimensions, the wind will reach a pipe located at a distance even of 2 or 3 feet from its source of supply without any appreciable interval between the impact of the finger on the key and the production of the sound; and the grooves may be curved almost as we please, though sharp angles should be avoided.

Even if, in consequence of alterations of original plans or other circumstances, the upper boards should not be of sufficient thickness or size to admit of grooving, we may still avail ourselves of this convenient system by using an additional or supplementary upper board, which we will here call a conducting board, screwed down upon the main upper board, and containing the grooves. To fix the exact places for the holes in the under side of the conducting board, corresponding with those in the table, spread a sheet of white paper over the upper board at the part where the conducting is to be, making the edges or corners of the paper coincide with those of the board, and rub the paper with the finger so as to take clear impressions of the holes; then transfer the paper to the under side of the conducting board, guided by the edges and corners as above, and prick out on this under side the centres of the circular impressions made on the paper. It is evident that when the conducting board is applied to the upper board, edges and corners coinciding as before, these punctured marks will be exactly over the wind holes in the table. The holes in the upper side of the conducting board will be marked as before from the rack-board, and grooves cut and roofed in with thin wood, as previously described.

Note further, that the grooving may be, if necessary, on both sides of the upper boards. All that is needful in such case is, that after the grooves on the under sides, next the sliders, are cut, the whole of the board, and not merely the grooved part of it, shall be covered or veneered with thin stuff. This must be dressed perfectly true, as in the case of the solid or ungrooved board, and all the holes will be bored through it. The upper sides will also have a neater appearance if the roofing of thin mahogany or cedar is carried over its entire surface. Upper boards so treated are, in fact, compounded of three layers of wood, a central thick slab containing the grooves, and two coverings or veneers. The gluing on of these latter must, of course, be very sound and effectual in every part, or a running of wind might ensue—a most provoking and really fatal defect, incurable without complete reconstruction.

Short grooves may be made by boring holes with a centre-bit in the edges of the upper boards, and making the wind-hole beneath and the pipe-hole above communicate with this concealed tunnel. On plugging up the external aperture in the edge of the board, or on stopping a whole row of such apertures by gluing a band of leather, parchment, or thick paper over them, it is clear that the wind will pass to the pipes at pleasure. All such holes and channels must be scorched with hot irons. To the true joiner this may seem an unworkmanlike expedient, but it is necessary to prevent the weakening of the currents of air which would ensue from friction against rough surfaces, and to preclude the risk of carrying tiny chips and particles of wood into the pipes. If conducting boards are used, they should be faced with soft white leather on their under surfaces before they are screwed down in their places, unless, indeed, they are glued down immovably. The places for the screws, as well as for those which secure the whole upper board to the table, must be carefully determined with reference to the grooves.

Fig. 12 is intended to show, in a rough way, how in an upper board BB grooves may conduct the wind from the holes in a slider AA to a row of pipe-holes near the margin of the board, resulting in an arrangement like that shown in Fig. 8. The dotted lines are meant to indicate grooves cut in the under side of the board. It is clear that these might be made to cross the others, so that different plantations of pipes might be obtained, as in Fig. 9.

Fig. 12.