Favorite Songs and Hymns For School and Home, page: 0177

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177

HeLMHOLTZ fixes the lowest limit of musical Bounds at sixteen vibrations per second, and the high�est at 38,000. Below this number the pulsations cease to link themselves together, and become dis tinct sounds. The range of the ear is thus about eleven octaves. The practical range of music is, however, only about seven octaves. The capacity to hear the higher tones varies in different persons. A sound which is entirely audible to one may be utter silence to another. Some ears cannot distinguish the squeak of a bat or the chirp of a cricket, while others are acutely sensitive to these shrill sounds. Indeed,	the auditory nerve seems generally more alive to the short, quick vibrations than to the long, slow ones. The whirr of a locust is much more noticeable than the sighing of the wind through the trees. A con�tinuous blast of air has no effect to produce sound. The rush of the grand aerial rivers above us we never hear. They flow on ceaselessly but silently in the upper regions of the air. A whirlwind is noise�less. Let, however, the great billows strike a tree and wrench it violently from the ground, and we can hear the secondary shorter waves which set out from the struggling limbs and from the tossing leaves.

THE HEART BOWED DOWN.		M. W. Balfe From "Bohemian Girl."..