The third part describes completing the soundboard and bridges, stringing, and then starting the case work.
Step 1: Fixing the Soundboard
Step 2: Downbearing, and a Description of the Top and Bottom Scales
It may be necessary to explain that these are 1/4in. slips of wood, with holes bored at regular distances, those of the top scale corresponding with the hammers, those in the other rather closer together, or, as it is termed, "contracted." For convenience of reference they are also lettered to the gamut in use, a pin is placed in each hole consecutively, and with the straight edge leaning against them; a line is ruled across the bent side, lower and top bridges, this line representing the right-hand string of each note.
Step 3: Drilling, Pinning and Notching the Bridges
The holes have a slight lean - the top bridge and top row of lower bridge towards the bass end, and the lower row of holes the reverse way.
The bridges have then to be glass-papered and blackleaded, the wood then cut away from the front of the holes, so that nothing touches the vibrating portion of the wires but the bridge pins.
Step 4: Drilling the Wrestplank and Stringing
The sizes of wire for stringing (music gauge) are 12 notes of No. 14, 12 of 15, 11 of 16, 16 of 17, 4 of 18, and 2 each of 19 and 20; for a trichord 1 size less so far as it extends; but before putting the strings on, a slip of baize must be laid all along the edges of the bent size and plate, to prevent the wire from jarring against them.
Step 5: The Case
In accordance with suggestions I think a case made after the French pattern (see diagram Fig. 2), and of solid walnut, will be most suitable for amateurs, as it will require neither special tools nor cauls for its construction.
The ends are 1in. thick, 48 1/2in. long, and 12in. wide. In glueing on, a margin must be left all round the lining; see dotted line (Fig. 2), the cheeks (C, Fig. 2), 1 1/2in.* thick by 12 by 7in. then being dowelled (not glued) to their position - viz., 22 1/2in. from bottom of end, and flush at the outside.
The key-bottom, being a framework of 2in. pine, with a back rail 1in. by 4in. wide (see Fig. 3), is then fitted between them and dowelled, by template, 1 1/4 in from their front edge, to allow for the lock-board, care being taken that the back of the key-bottom is not touching any portion of the bridge. To make sure of this it is advisable to try all together before glueing.
Any measurement required may be taken from Figs. 2 and 3, they being drawn to a scale of 1 in 12.
The front plinth can now be got out. This is let in between the ends with the exception of a shoulder projecting beyhond them 1/4in. and forming with the side plinths a border all round of that thickness.
An inside bottom (C, Fig. 2) is to be fitted to fill up the space between the ends and plinth. This can be dowelled or nailed through from outside the end, as the side plinth will cover the holes.
W. H. Davies
(from The English Mechanic and World of Science vol. 27, August 2, 1878, p.514-515)