730. Why are some notes low and solemn, and others high and quick?
Because the vibrations of musical strings vary from 32 vibrations in a second, which produces a soft and deep bass, to 15,000 vibrations in a second, which produces the sharpest treble note.
731. Why can our voices be heard at a greater distance when we speak through tubes?
Because the vibrations are confined to the air within the tube, and are not interfered with by other vibrations or movements in the air; the tube itself is also a good conductor of sound.
"And I will cause the noise of thy songs to cease; and the sound of thy harps shall no more be heard."—Ezekiel xxvi.
732. Is air a good conductor of sound?
Air is a good conductor, but water is a better conductor than air; wood, metals, the earth, &c., are also good conductors.