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Lyttelton Times, Volume CXV, Issue 16488, 2 March 1914, Page 8

Many of the shells found on the seashore inclose a column of air which comes curiously into vibration within the limit of its capacity for response in resonance. Thus the shell may collect sounds which would pass unnoticed upon the ear, and, by re-enforcing and condensing them, make them audible. The source of the original sound thus collected into audibility is not simple in determination. Tyndall ascribes a share of the sound to the collection and concentration in this resonator of the harmonic sound present in the air, but unnoticed; a share to the,pressure of the shell upon the outer ear. To the physiologist, a third source suggests itself, the arterial pulsation in the vicin-