Science and music / [by Sir James Jeans].

  • Jeans, James, 1877-1946.
Date:
1947
Catalogue details

Licence: In copyright

Credit: Science and music / [by Sir James Jeans]. Source: Wellcome Collection.

    113/300 (page 91)
    another, the result is a sharp shrill sound of metallic quality (p. 87)—it is, in fact, the noise we hear if we accidentally drop a key or a coin on to a piano-wire. The following table exhibits the results just mentioned, and shews the contrast between the two types of sound we have so far considered: Distribution of Energy between the various Harmonics of a String Ordinal number of 1 2 3 4 5 6 7 harmonic Note c' c g c' e' g' bb' Energy when plucked 1 1 4 £ 1 T7 1 •?v Energy when struck 1 I 1 I 1 I I Ordinal number of 8 9 10 I I 12 13 14 harmonic Note civ div eiv — giv — bbiv Energy when plucked 1 ei 1 “ST t£tt 1 T5T 1 m rihr Energy when struck I I I I 1 1 I Piano Tone In the piano the wire is struck with a hammer covered with soft felt. The felt prolongs the duration of the impact, so that, by the time that the hammer finally breaks its contact with the string, a substantial length of the string has already been set in motion. This reduces the energy which goes into the higher harmonics, and so avoids the harsh jangle of sound represented in the bottom column of the above table. As we have seen that discord begins with the seventh harmonic, the hammer should be sufficiently felted to reduce the seventh and higher discordant harmonics (ninth, eleventh, etc.) to small proportions.