The New International Encyclopædia/Harmonic Stop

HARMONIC STOP. An organ-stop, having pipes double the usual length, and pierced mid-way, so that the tone produced is an octave higher than the ordinary pitch. Harmonic stops are composed generally of more than a single rank of pipes, tuned in octaves, double octaves, and double or triple thirds and fifths above the natural pitch of the keys; they comprise the mixture, furniture, cornet, etc. Those which have only a single rank of pipes tuned in thirds, fifths, with their octaves above the pitch represented on the keyboard, are called &lsquo;mutation stops.&rsquo; They were introduced to give additional power to the &lsquo;foundation stops,&rsquo; and also to produce a more brilliant effect in the performance of certain styles of music. See.