Letters On Natural Magic Addressed to Sir Walter Scott
The book Letters On Natural Magic Addressed to Sir Walter Scott was written by author David Brewster Here you can read free online of Letters On Natural Magic Addressed to Sir Walter Scott book, rate and share your impressions in comments. If you don't know what to write, just answer the question: Why is Letters On Natural Magic Addressed to Sir Walter Scott a good or bad book?
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Along fluid and solid bodies, its progress is still more rapid. Through water it moves at the rate of 4708 feet in a second, through tin at the rate of 8175 feet, and through iron, glass, and some kinds of wood, at the rate of 18, 530 feet. When a number of single and separate sounds follow each other in rapid succession, they pro- duce a continued sound, in the same manner as a continuous circle of light is produced by whirling round a burning stick before the eye. In order that the sound may ...appear a single one to the ear, nearly sixteen separate sounds must follow one another every second. When these sounds are exactly similar, and recur at equal intervals, they form a musical sound. In order to produce such sounds frem the air, it must receive at least sixteen equally distant impulses or strokes in a second. The most common way of producing this effect is by a string or wire AB, Fig. 40, stretched between the fixed points A, B. If this string is taken by the middle and pulled aside, or if it is suddenly struck, it will vibrate between its two fixed points, as shown in the figure, passing alternately on each side of its axis AB, the vibrations gradually diminishing by the resistance of the air till the string is brought to rest.
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