Elements of natural philosophy (Volume 2-3) . redto in § 56, any number of the various modes of vibra-tion of which a cord is susceptible, may be going onsimultaneously. Thus, if we suppose amode of vibration repre-sented by figure (a), inwhich there is no node,and another of the samecord represented by figure(J), with one node, to begoing on at the same time,there will be a resultantvibration represented bythe curve in figure (c), of which the ordinates are equal to the algebraic sum of thecorresponding ordinates of the curves in figures (a) and(5). If a third mode of vibration, represented b
Elements of natural philosophy (Volume 2-3) . redto in § 56, any number of the various modes of vibra-tion of which a cord is susceptible, may be going onsimultaneously. Thus, if we suppose amode of vibration repre-sented by figure (a), inwhich there is no node,and another of the samecord represented by figure(J), with one node, to begoing on at the same time,there will be a resultantvibration represented bythe curve in figure (c), of which the ordinates are equal to the algebraic sum of thecorresponding ordinates of the curves in figures (a) and(5). If a third mode of vibration, represented by figure(6?), be superposed upon the other two, there will arise aresultant vibration represented by the curve in figure (V),of which the ordinates will be equal to the algebraicsum of the corresponding ordinates in figures (a), (b) and(d), or, which is the same thing, the algebraic sum of thecorresponding ordinates of figures (c) and (d). This is also confirmed by experience. It was longknown to musicians, that besides the fundamental note. ELEMENTS OF ACOUSTICS. m of a string, an experienced ear could detect in its sound, Harmonicwhen in motion, especially when very lightly touched B0Unds»in certain points, other notes related to the fundamentalone by fixed laws of harmony, and which are thereforecalled harmonic sounds. They are the very sounds thatmay be heard by the production of distinct nodes as ex-plained in § 99, and thus insulated as it were from thefundamental and other coexisting sounds. § 101. The Monochord is an instrument adapted to ex-Themonochord;hibit these and other phenomena of vibrating consists of a single string of catgut or metallic wirestretched over two fixed and well defined edcres to-wards its extremities, which effectually terminate itsvibrations in the direction of its length; one end ispermanently fixed, and to the other is attached aweight which determines the tension. The interval be-Essential parts;tween the two edges is graduated
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