VALVES or PISTONS, in music, are mechanical contriv ances applied to wind instruments in order to establish a connection between the main tubing and certain supplementary lengths re quired for the purpose of lowering the pitch. Various devices have been tried from the days of ancient Greece and Rome to produce this effect, the earliest being the additional tubes inserted into the lateral holes of the aulos and tibia (qq.v.) in order to prolong the bore and deepen the pitch of each individual hole; these tubes were stopped by the fingers in the same manner as the holes. This device enabled the performer to change the mode or key in which he was playing, just as did the crooks—or coils of tub ing inserted between the mouthpiece and the main tube in the trumpet and horn, and between the slide and the bell joint in the trombone—many centuries later.
But the resourcefulness of the ancients did not stop there. The tibiae found at Pompeii had sliding bands of silver, one covering each lateral hole in the pipe; in the band were holes (sometimes one large and one small, probably for semitone and tone) corres ponding with those on the pipe. By turning the band the holes could be closed, as by keys, when not required. By fixing the Mot in the holes of the bands, the bore was lengthened instantly at will, and just as easily shortened again by withdrawing them ; this method was more effective than the use of the crooks, and foreshadowed the valves of eighteen centuries later. The crooks, or coils of tubing inserted between the mouthpiece and the main tube in the trumpet and horn, and between the slide and the bell joint in the trombone, formed an important step in this direction.
Although the same principle underlies all these methods, i.e., the lengthening of the main column of air by the addition of other lengths of tubing, the valve itself constitutes a radical dif ference, for the adjustment of crooks demands time and the use of both hands. The action of the valve being as instantaneous as that of the key, the instrument to which it was applied was at once placed on a different basis, becoming a chromatic instrument capable of the most delicate modulations from key to key.
The slide had already accomplished this desirable result, but as its application was limited to instruments of which the greater part of the bore was cylindrical, i.e., the trumpet and trombone, its influence on concerted musical composition could not be far reaching. In fact it is doubtful whether the chromatic possibil ities of the slide were fully realized until the end of the i8th century, when, key mechanism having made some advance, it was being applied successfully to the transverse flute, and to the clarinet and oboe families.
In 176o Kolbel, a Bohemian horn-player engaged in the St. Petersburg Imperial Orchestra, turned his attention to this method of extending the compass of brass instruments. His experiments, followed up by Anton Weidinger of Vienna at the beginning of the 19th century, produced a trumpet with five keys and a complete chromatic compass. Halliday followed with the keyed bugle in 181o. Halary applied the principle of the keyed bugle to the bass horn in 1817, and produced the ophicleide—an ideal chromatic bass as far as technical possibilities are concerned. The horn had become a chromatic instrument through Hampel's discovery of bouche sounds, but the defects in intonation and timbre still re mained. Such were the conditions when the successful applica tion of the valve to brass wind instruments by Heinrich Stolzel of Silesia brought about an entire revolution in the design and con struction of these instruments. Further efforts to perfect the key system as applied to the brass wind were abandoned in favour of valves, and the short space of two decades witnessed the rise of the Flidgcl-horns, the tubas, the saxhorns and the cornet-a-pistons; the trombone, French horn and trumpet having led the van.
Although the valves of brass wind instruments vary in form and detail according to the makers, the general principles governing their action are the same for all types. The piston, placed on some branch of the main tube, must be so constructed that on be ing depressed it closes the natural windways through the main bore and opens others into the additional piston length. The piston, seated on a spring, instantly regains its normal position when the finger is removed. The length of tubing attached to each valve is calculated on the basis of the length of the main column, to give for the first piston a tone, for the second a semi tone, for the third a tone and a half, and for the fourth two tones.
There was, however, a difficulty at first. In the early valved instruments it was found that the intonation of the notes yielded by the combined pistons was seriously inaccurate, an increase in the length of the additional tubing being required to give the right results, and it took many years before the instrument makers succeeded in satisfactorily overcoming this defect and producing the perfected instruments of the present day.
Although the accredited inventor and patentee of valves applied to musical instruments was Heinrich Stolzel, of Pless in Silesia, the actual inventor was really one Bliimel, also a Silesian, who sold his rights to Stolzel in 1815.