A first book in psychology / by Mary Whiton Calkins.

  • Mary Whiton Calkins
Date:
1910
Catalogue details

Licence: Public Domain Mark

Credit: A first book in psychology / by Mary Whiton Calkins. Source: Wellcome Collection.

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    atmospheric wave. (a) The consciousness of pitch is, in all probability, occasioned by a succession of simple and regular atmospheric waves. The experience of noise is probably due either to a momentary unperiodic vibration, or to a com¬ bination of air-waves of nearly identical length — for example, to the complex of air-waves which are set into vibration when one simultaneously strikes a great number of piano keys. Different qualities of pitch are found by experiment to cor¬ respond to the varying length of the atmospheric waves. The swifter the atmospheric vibrations, that is, the greater the number and the shorter the length of the air-waves in any second of time, the higher is the pitch-quality; and, on the other hand, the slower the vibrations, that is, the fewer and longer the air-waves in a second, the lower or deeper is the pitch- quality. This is the principle on which all stringed instru¬ ments are constructed. The shorter strings of the piano are struck to produce its higher notes; and the violinist’s finger divides his string to obtain from the swifter air-vibrations, propagated by the motion of each half, a tone an octave higher than that produced by the slower vibration of the entire length. As, therefore, a definite number of ether-vibrations corre¬ sponds with each experience of color, so each consciousness of pitch has its air-vibration number: the consciousness of low c, for example (in what is called the small octave), is produced, through the excitation of nerve-endings and brain-cells, by one hundred and twenty-eight vibrations; and that of its octave, c', is excited by exactly twice as many, or two hundred and fifty-six vibrations. (b) The amplitude of an atmos¬ pheric wave, that is, the length of the extreme excursion (one way or other) of each air-particle is the condition of our con¬ sciousness of sound-intensity; and the wave diffusion (the
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