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.

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    greater range of effects at his disposal than the child strumming at its five-finger exercises. To put this last matter beyond doubt, three American scientists, Hart, Fuller and Lusby, of the University of Pennsylvania, have recently made records of the sound curves of single notes played by well-known virtuosi, and also of the same note played by letting a weight fall on the keys. Two pairs of such curves are shewn in figs, i and 2 on Plate IV. In each case the upper curve records the note played by the professional, the lower curve that played by the falling weight. No visible difference can be detected. Making the string produce the desired quality of tone is only the first problem of pianoforte manufacture; the second is the transmission of this tone to the hearer. A metal wire has so small a diameter that its vibrations transmit but little energy to the surrounding air; this is why the harp produces so feeble a sound. The pianoforte produces a fuller sound by enlisting the help of a wooden sound¬ board, which is made as large as the framework of the instrument permits. Securely fixed to this sound-board is a bridge over which the wires of the pianoforte pass; this transmits the vibrations of the wires to the sound-board. When the sound-board takes up these vibrations, its large surface sets a considerable mass of air into agitation, so that the sound is heard in ample volume even at a good distance. It is important that all parts of the sound-board should be vibrating in the same phase, otherwise the vibrations from different parts of the board will neutralise one another in the way explained on p. 46. This requires that the sound¬ board shall be built of a wood in which sound travels very rapidly. Norway spruce, in which sound travels at three 7-2