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Updated: May 3, 2025
Enlightenment and instruction of all kinds will be given by means of phonographic books. The sound-wave will, in a word, be substituted for the light-wave as the vehicle of all our best information and intercourse. The ear will have habitually taken the place of the eye in the principal offices of interest and information.
When a sound-wave strikes the ear, we hear; when a light-wave, moving like a water-wave, reaches the eye, we see. Light comes chiefly from the sun: it is beautiful to think, is it not? of waves of light streaming always, day and night, from that wonderful sun so far away, and coming, wave after wave, to paint beautiful pictures on our eyes!
In like manner, when one knows the velocity and wave-length, he may compute the number of vibrations by dividing the velocity by the wave-length. Now the velocity of the waves called light is 186,000 miles a second, and a light-wave may be one forty thousandth of an inch long.
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