Thus an evident explanation is offered, of all the curi ous harmonic effects of several unison strings on the /EoLiAtc Harp, (see that article) when agitated by irregu lar gusts of wind : acting momentarily on the whole string, and on its different nodes, with sufficient force to excite the determinate vibrations, which the elasticity of the string, and its parts, dispose them severally to take ; but all of which vibratory motions are so vastly quicker than the mere motion of the wind, that we cannot agree with Dr Matthew Young in thinking, that particular tones are ex cited, or kept up, by that means.
We have calculated the values of all the aliquot parts of a string or pipe (in Fancy's Notation of Intervals) above the note of the whole string, viz. &c. as far as • and deducted octaves, so as to bring them all within the compass of one octave; and the same, when arranged under their respective finger-key intervals, stand as follows, viz.
Wherein the errors or temperaments of all these acute harmonic notes are set down ; and hence we perceive clearly the reason why a sound is accompanied chiefly by its VIIIth, Vth, and 2 VIII IlIrd, and rarely by any other of its harmonics, viz. because -I of the string
is strengthened, or reinforced by four other octaves to it the XIIth (or V) is reinforced by 3 other octaves to it, and the XVIIth (o• III) by two other octaves to it ; and these three are the only concords to the whole string, that are found among its numerous harmonics. The II and the VII, each with the reinforcement of an octave thereto, should, and accordingly are, next heard in the order of acute harmonics. The harmonic 6th, being a diatonic in terval, viz. 6—f,, whose ratio is -4,= 394 Z + 8 f 34m, may perhaps, under very favourable circumstances, be heard as an acute harmonic : but when the very discord ant nature of all the remaining sounds in one table, both with the generator and with all of its other harmonics, respectively, are considered, it seems very plain why these sounds, although momentarily produced by a gust of wind, or other impulse, on the proper part of the string, almost immediately die away. and cannot be maintained, as the VIllth, XIIth, and XVIIth may be, and others, in less degrees. (0