merely a matter of careful adjustment, as the increase progresses regularly upon a definite formula as in the case of a mathematical curve; and let it be again clearly understood that the division of the scale is merely a secondary matter and that other colour scales might perhaps be used with great advantage.
The method of musical notation being adopted as to the treble and bass clefs, time values of notes, etc., the ordinary musical directions such as diminuendo, crescendo, allegro, etc., can, of course, be used, and it becomes relatively easy for the executant to use the ordinary form of colour-organ.
Later on it was found convenient to have an alternative arrangement under which the spectrum-band can be spread over the whole of the five or six octaves of the keyboard. By the use of a pneumatic device, the simple withdrawal of a stop has the effect of doing this. A musical system of notation can still be employed, but when this stop is in use, of course, any direct translation of a musical composition is impossible, and a score written with the intention of using this arrangement
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