Cut the mortices right through the soundboard, and clear them out nice and smooth; those in the bass may be cut back on the under side, as shown by the dotted line in Fig. 199.
Cover the top of the board with a piece of stout veneer - sycamore being the best - which should be glued and clamped tightly down, and, when thoroughly dry, the pallet-holes may be cut through it, those at the bass end being 1 in. long and rather more than 1/8 in. wide, and gradually diminishing in size up to the treble. You can mark these out in the same way as the mortices. Having done this, take some 1/2-in. beech, or pine, 2 in. wide, and box round the edges of the sound-board fair on top side, the boxing projecting on the under side only. Now get out a bar of beech 1 in. square and 2 ft. 6 in. long, and glue it down on the top of the soundboard, so that the centre of it is 2f in. from the centre of the pallet-holes. Run a deep gauge mark all down the centre of the top of this bar to receive the centre wire on which the pallet levers work. Cut out 54 grooves in the bar in a line with the pallet-holes; this may be done by tying two small tenon saws together. Now make the pallets and levers, as in Fig. 199, the levers being made first and bored through the centre with a fine bradawl, or drill. The hole in the end to receive the long thin screw can be best made by screwing the lever lightly into a vice, and the screw can also then be inserted without danger of splitting the wood.
The pallets themselves are made large enough to cover the holes well, and are tapered off at the top as shown. They are covered with soft leather on the under side, and whiting should be well rubbed into the leather with a little block of wood. In glueing the pallets on to the levers, some place a piece of stout soft leather between the lever and the pallet.
String the levers on to the centre wire, put them into the proper grooves, and press the centre wire down into the gauge mark; then glue a piece of wood 1/4 in. thick on each end of the bar, with a hole in it level with the gauge mark to receive the ends of the centre wire, which may be drawn out from either end if required at any future time. Just at the back of the pallets, fasten a strip of wood exactly thick enough to be level with the tops of the levers; this is to fasten the pallet springs in. The springs are made of tolerably stout piano wire, bent into the form shown, the front end being turned up to run in a gauge mark on the top of the lever, the back end turned down and fixed into the strip of wood above referred to; a small screw being inserted close behind it, so that the head holds the wire well down, or a small loop may be made in the end of the spring and the screw passed through that.
It may be of service to mention a plan for entirely dispensing with these steel springs. Bend some pieces of wire thus -, and insert one between every pallet lever, just behind the centre bar. Then procure from a draper, 2 1/2 yd. of covered elastic band that will stretch well, and, having made a loop at one end, slip it over the first wire crook, then over the first pallet lever, under the next crook, and over the through. This plan is simple and answers well; when the elastic does wear out, it can be renewed with very little trouble, and at a cost of only a few pence. The band should be § in. wide, and contain at least 6 strands of elastic.
The vibrators may now be screwed on to the under side of the sound-board in the position shown in Fig. 199, and the sound-board may then be considered complete. It should be hung by a peg through each end, which is made to project 3 in. for that purpose, the peg running into the cheek blocks, so that the sound-board may be turned down as on a hinge, and lie flat on the wind-cheat. Make a little roll of cloth, cover it with soft leather, and fasten it all round the under side of the sound-board; then fix 3 iron hooks in the side, and 2 eyes in the wind-chest, so that when the soundboard is turned down on to the wind-chest, and the hooks are fastened into the eyes, there can be no escape of wind from the wind-cheat, except through the vibrators and pallet-holes. The keyboard will best be purchased, either new or second-hand. When it is placed in position, the screws in the ends of the levers should come under the proper keys, so that when the key is pressed down it opens the pallet belonging to.
A folding lid should be made to the case, and hinged at the hack edge ho that it may be turned right back if required to gat at the interior of the instrument. Finish off the case in any style you may fancy, and your harmonium will be completed. If the case is mode of mahogany, all that need be done is to French polish the exterior, but if it be made of pine, it should be stained and Tarnished, or ebonised.
Fig. 199 is a sectional view of the bass end of the sound-board or pan: a, vibrator; b, screws by which vibrators are tiled; c, mortice; d, soundboard ; e, beech boxing round soundboard ; f, pallet; g, pallet lever; A, pallet lever-rail; i, spring rail; f, spring; k, wire crook; I, elastic band in lieu of steel spring; m, screw on which key rests; n, veneer; o, roll of cloth board; i, folding side to case; j, wedges to secure reservoir-board. (T. Main, in Amateur Work.)
These delicase instruments are very liable to get out of repair, either by direct violence or by neglect, a small defect sufficing to render them temporarily useless. Whilst it would be futile for any one ignorant of their construction to attempt remedying accidental defects, a small knowledge of the first principles of their mechanism will enable any ordinarily handy workman to repair all but very serious injuries.