Elementary natural philosophy : designed for high schools and academies (1881)
Griffin, La Roy F. (La Roy Freese), 1844-1916 · Philadelphia : Sower, Potts & Co. · leaf 139
e are placed parallel, the lineis lengthened. If they vibrate at different rates, the lineis alternately lengthened and shortened. Thus the beatswhich the ear distinguishes are made plain to the eye. 470. If two forks are placed at right angles, one pro-duces an image which is horizontal, and the… … 130 ACOUSTICS. El 1 1 1 tave, they produce a figure eight, as shown in Figure 156. 471. These experiments may be continued with forks varying in any pro-portion, and eachcombination willgive its appropriatefigure. The fol-lowing illustration,Figure 157, showssome of these, thefractions undereach…
Physics
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