We are mindful, of course, in drawing up this account of organ-building operations, that the majority of our readers stand in no need of definitions of these common terms. To such readers it is superfluous to explain that the valves by which the channels are kept closed while the keys are untouched by the fingers are called "pallets," and that these pallets are slips of wood a few inches in length, planed to a triangular prism-like section, faced with soft white leather, and held up against the channels, so as effectually to prevent the ingress of air, by springs. When the keys are pressed, the pallets corresponding to them are drawn down or opened by wires called "pull-downs," passing in an air-tight contrivance through the bottom of the chest.
Fig. 13 is a transverse section of the wind-chest, in which a is the pallet, held up by b, the spring, and drawn down by c, the wire. Part of the sound-board is shown above, also in section, as will be easily comprehended; and Fig. 14 is a view of part of the interior of the wind-chest when the front board is removed, four of the grooves being shown in section.
We proceed by sections, with intervening remarks, as in Chapter III.
Fig. 13.
1. Seven inches will be an ample length for the pallets in our organ; and as our channels are about 12½ inches in length (inside measurement), there will be between 5 and 6 inches of the channels uncovered by the pallets, and closed permanently in another way.
Remark.—We take 7 inches as the length of our pallets on the assumption that the widths of the channels are proportioned to a sound-board about 4 feet long.
Fig. 14.