In reed organs it depends tom the adjust ment of the comparative weight, length and thickness of the reeds, and in pipe organs upon the length of the vibrating column of air in the flue pipes.
In the tuning of strings, the pitch is deter mined by the size,, length and tension of the wire. In reed tuning the desired pitch is ob tained by filing or scraping the reed; at the base or fixed end to flatten the tone and at the point or free end to sharpen it.
Organ pipes are tuned according to their construction. The large open flue wood pipes are lowered or flattened in pitch by being lengthened by a sliding cap or by a board fas tened to the back, at the top, and is raised or sharpened in pitch by being shortened.
The large open metal flue pipes are tuned by cutting away or adding to the length or by a slit in the back near the top, making two flaps to be opened or closed as required; clos ing them lowers the pitch, opening them raises it; the small metal pipes being tuned by the use of a conical horn, with which the tops of the pipes are contracted or expanded, as the pitch is to be lowered or raised respectively. Stopped metal pipes are tuned by a cap, raised or lowered as desired, and reed pipes by adjust ing the wire which bears upon the reed, the raising or drawing up of the wire increasing the effective length of the reed and so flattening it and vice-versa. In the twining of pipe organs, the reed pipes are the last to be tuned, since they are the most liable of all the pipes to be come disarranged.
Voicing of Keyed Musical Instruments.—
The voicing of organ consists in the ad justment of their various parts, consisting of the mouth, throat, lips, languid and ears, the correct method of treatment having been learned by experience many years ago and of late years demonstrated by mathematical calcu lations and by the investigations of scientists.
The languid is that flat piece of the pipe which lies horizontally above the upper part of the foot, and it is against this languid the (sheet of winds is forced from the ((wind ways below. Some of the pipes have the languid3 grooved upon their face, as one method of voicing, and some metal pipes are voiced by bending the ears, which are placed on either side of the mouth. Pipes once voiced at the factory seldom need any alteration.
The voicing of reeds in the common house organ is accomplished by giying the free end of the reed a slight curl or circumflex, and this also causes the reed to speak or sound more promptly and with less pressure of wind.
The voicing of pianos consists in the stab bing of the felt of which the hammers are made, by several needles fastened in a handle. The thrusts should be made directly toward the centre of the hammer and not through the top of the felt, from the sides. In the making of hammers, which is done by machinery, one entire set being covered with felt at a time, there is a variation as to hardness in the indi vidual hammers, and voicing is relied to lighten up the felt and give a uniform char acter of tone throughout the entire scale Of the piano.