Johnson's natural philosophy and key to philosophical charts : illustrated with 500 cuts; being reduced photographic copies of all the diagrams contained in the author's philosophical series of indestructible school charts ; for the use of schools and families (1878)
Figure 29 represents nodal figures of a triangular plate. Fig. 20. moo Refraction of Sound. 581. Figure 30.—Refraction of sound.—Althongli soundis reflected by any surface of different density from that in which it Fig. ?>0. … 320 ACOUSTICS. originates, the sound also enters the second medium by means of newvibrations, originating at the interposed surface. A cell, S, made of two films of collodion, united at the edges, andhaving the form of a double convex lens, as shown, will serve to demon-strate refraction of sound.…
Physics · Astronomy
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