Acoustics & Sound For Musicians - Online Book

The Theory Of Sound Which Constitutes The Physical Basis Of The Art Of Music.

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78                    RESONANT AIR COLUMNS.         [III. § 39.
in the second only the unassisted tone of the fork, and the contrast is very marked. We may shorten or lengthen our cylinder within certain limits and still obtain the phenomena of resonance, but the greatest reinforcement of tone we can attain with the fork selected will be produced by an air-column about twelve inches long.
If we close one end of the paper cylinder, by placing it, for instance, on a table, and repeat our ex­periment at the open end, only a very weak resonance is produced; but we obtain a powerful resonance by
as many vibrations per second as that before em­ployed. In this case, then, a column of air contained in a cylinder of which one end was closed resounded powerfully to a note an Octave below that which elicited its most vigorous resonance when contained in a cylinder open at both ends.
By operating in this fashion, with forks of dif­ferent pitch, on air-columns of different lengths, we arrive at the following laws, which are universally true:—
1.     For every single musical note there exists a corresponding air-column of definite length which re­sounds the most powerfully to that note.
2.     The maximum resonance of air in a closed
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