When all the pipes are planted, whatever the arrangement which you have adopted, they should gratify the eye by their perfect symmetry.
"If they do not look well they will not sound well," was a good maxim long ago impressed upon the writer by an ingenious German workman, to whom he was indebted for much valuable information.
THIS important subject will be prefaced by a few definitions, superfluous, perhaps, for some readers, necessary for others.
_Backfall_. A lever of any clean wood, 3/8 inch or less in thickness, 1 inch or 2 inches in width, and seldom more than 1 or 2 feet in length, turning upon a wire as its axis or fulcrum.
_Bridge_. Backfalls occur in sets, corresponding to the number of keys in a manual or of pallets in a wind-chest. They are arranged side by side in notches formed by taking out the wood between saw-cuts in a balk of mahogany or oak 2, 3, or more inches square. This balk is called a bridge. Fig. 27 shows part of a set of backfalls and their bridge.
_Square._ Squares are now usually of metal, but may be easily made of wood, and consist of two arms, 2 or 3 inches long, united at a right angle to each other, or cut at once from a single piece, and turning on a wire as an axis passing through a hole at the intersection of the arms. Like the backfalls, they may be arranged side by side in a bridge, but the modern metal squares are screwed separately in their places (Fig. 28).
_Sticker._ A slender rod of light wood, not larger than a common cedar pencil, and from a few inches to a foot or two in length (Fig. 29).
_Tracker._ A flat riband of pine, sometimes several feet in length, about 3/8 inch in width, and less than 1/8 inch in thickness. Trackers, however, are now frequently slender round rods, like the stickers (see Fig. 30).
_Tapped Wires._ Formerly of brass, afterwards of tinned iron, and now generally of phosphor-bronze or some other alloy. These are pieces of wire about 3-1/2 inches in length, from No. 16 to No. 18 in gauge, and cut with a screw-thread upon about half their length, with a ring or hook at the untapped end.
_Buttons_. Round nuts of old and thick leather, or latterly of a composition into which gutta-percha enters, pierced at their centre to receive the tapped part of the wire.