Scan 18
Stokes Encyclopedia Of Music And Musicians, 1908
8 lines. Read by computer on 18 September 2026. No printed page number was found. See the scan on archive.org.
1there the following year. In 1788 Mozart rescored the work for Van Swieten.
3A Cinque. Fr. In five parts.
5Acoustics is the science which deals with sound and the laws which govern it. When a tuning fork is struck the vibrations of its prongs may be seen and felt. Corresponding vibrations or sound waves are set up in the air, by which they are communicated to the ear, which in turn conveys the sensation of sound to the brain. If the fork be struck violently the AMPLITUDE of VIBRATION and consequently the intensity of the sound will be greater than if struck gently, but until the vibrating prongs have returned to rest the sound waves set in motion will be periodic and of uniform length. If the fork indicate a' of French or International pitch, these sound waves will be propagated at the rate of 435 per second. The essential of sound, by which we have come to mean musical tone as distinguished from mere noise, is regularity of vibration, and whether the sound wave is set in motion by an elastic string as when open A is sounded on the violin; by a reed, as when A is intoned on the oboe; by an enclosed column of air, as in the case of an organ pipe; a given number of vibrations per second will always produce a tone of the same pitch. The quality of a given tone sounded by various instruments or voices shows wonderful variety, however, due the fact that, in addition to the principal tone sounded, which alone is audible under ordinary circumstances, higher and softer tones appropriately called "overtones" or "upper partials" are almost invariably produced, blending with the principal tone and modifying its quality. Thus when an open string is set in vibration it produces a principal tone, high or low, in proportion to its length, size, and tension, but the string divides itself into several vibrating segments, separated by nodes or spots of minimum vibration, and these segments vibrating twice, four, or six times as rapidly as the entire string, produce the harmonics called overtones. Such open pipe instruments as the flute give overtones in the ratios of 1, 2, 3, and 4. The overtones of a closed pipe are in the ratio 1, 3, 5, 7, and this ratio governs in the case of clarinets, which are closed at one end by the mouthpiece. The complete series of overtones are given by brass instruments, and the tones are further modified in quality by the form of the tube, the bell, etc. Computation of the number of vibrations required for a given tone has been made simple and certain by the toothed wheel and the siren, and it has been established that, to the average human ear, appreciation of pitch begins with vibrations of from eight to 32 per second, and ends with 40,000 vibrations per second. The octave of any tone may be obtained by doubling the number of vibrations by which it is produced. Other proportions need not be given here because, with this exception, in equal TEMPERAMENT (whereby the octave is divided into twelve nearly equal semitones) there are no true intervals. In theory the intensity of sound diminishes with the inverse square of the distance from its source, but this loss of the volume of tone is counteracted by the use of sounding boards and resonators. Volume of tone in musical instruments is often magnified in the same manner. A violin string in vibration sounds faint in itself, but the vibrations are communicated to the belly of the instrument by the bridge, and to the back by the sounding board, and the tone is thus made louder. Sound waves travel in air at the rate of 1090 feet per second at 32 F. and between one and two feet faster per second with every additional degree of warmth. They traverse water at the rate of 1435 feet per second, iron at the rate of 5030 feet per second. They may be reflected as light waves are, producing the phenomena of echoes and whispering galleries.
7Act. Natural division in the drama was effected by the Greek chorus, but in the time of Horace the Act had come to be one of five divisions of a play, each more or less complete, and with its own climax. Wagner favoured
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