A complete view of Acoustical Science & its bearings on music, for musicians & music students.

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Fig. 34.
drop of sealing wax, hanging down like a pendulum against the membrane. If now anyone places himself in front of the aperture, and sings up and down the scale, on reaching some particular sound the pendulum will be violently agitated, showing that the mem­brane and the air within the bottle are vibrating in unison with that note.
Another simple experiment of the same kind can be performed with a common tumbler. Moisten a piece of thin paper with gum,
Fig. 35.
and cover the mouth of the tumbler with it, keeping the paper on the stretch. When dry cut away a part of the paper as seen in fig. 35. Put a few grains of sand, or any light substance on the cover.