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108 POINT OF PERCUSSION. [V. § 54.
forms shown in Figs. 27, 28, 35, 36, or in forms with larger numbers of segments. The rapidity of vibration in any one of these forms is, as we have seen [§ 52], proportional to the number of segments formed, so that, with two segments, it vibrates , with three, thrice, with four, four times, as fast as in the form with one segment. It follows hence [§ 43] that the notes obtained by causing a string to vibrate successively in forms with 1, 2, 3, 4, 5, &c, segments are all partial-tones of one compound sound, the lowrest being of course its fundamental-tone.
The modes of eliciting the sounds of stringed instruments described on the preceding page are not capable of setting up any one of the above forms of vibration by itself, but give rise to a movement which is the resultant of several such vibration-forms compounded together. Each separate vibration-form thus called into existence sings, as it were, its own note, without heeding what is being done by its fellows. Accordingly, a certain number of tones belonging to one family of partial-tones are simultaneously heard.
How many, and which, members of the general series of partial-tones are present, and with what relative intensities, in the sound of a string set vibrating by a blow, depends on the position of the point at which the blow is delivered, on the