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VALVE (Lat. valva, a leaf of a double...

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Originally appearing in Volume V27, Page 875 of the 1911 Encyclopedia Britannica.
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VALVE (Lat. valva, a leaf of a double or folding door, allied to volvere, to roll, as of a door on its hinges), a term applied to many mechanical appliances, devices or natural features,which control, by opening and shutting, the flow of air, liquids, vapour, gas, &c., through a passage, tube, pipe or other vessel. VALVES, or PISTONS (Fr. pistons, cylindres; Ger. Ventile; Ital. piston), in music, mechanical contrivances applied to wind instruments in order to establish a connexion between the main tubing and certain supplementary lengths required 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 (rrXaycau Mot) inserted into the lateral holes of the aulos and tibia 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 many centuries later. But the resourcefulness of the ancients did not stop there. The tibiae found at Pompeii (see Aunos) 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) corresponding with those on the pipe. By turning the band the holes could be closed, as by keys when not required. By fixing the 6 of 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 a 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 difference, for, the adjustment of crooks demanding time and the use of both hands, they could only be effective for the purposes of changing the key and of rendering a multiplicity of instruments unnecessary. 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; it became 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 possibilities of the slide were fully realized until the end of the 18th 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 were concerned. The horn had become a chromatic instrument through Hampel's discovery of bouche sounds, but the defects in intonation and timbre still remained. Such were the conditions prevailing among the wind instruments of the orchestra when the successful application of the valve to brass wind instruments by Heinrich Stolzel of Silesia caused an instantaneous revolution among makers of wind instruments. Further efforts to perfect the key system as applied to the brass wind were abandoned in favour of valves. The short space of two decades witnessed the rise of the Fliigelhorns, the tubas, the saxhorns and the cornet-a-pistons; the trombone, French horn and trumpet having led the van, Sound is produced on brass wind instruments by overblowing the members of the harmonic series (see Hoax). ' The harmonic series itself is invariable, whether obtained from a string or a column of air; the structural features of the instrument determine which members of the series it is able to produce.
End of Article: VALVE (Lat. valva, a leaf of a double or folding door, allied to volvere, to roll, as of a door on its hinges)
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