as soon as the keys are depressed. The designing of this mechanism has been one of the great difficulties in the construction of the various instruments, as it was, of course, absolutely necessary that it should be responsive to the slightest touch upon the keys, and yet had to be far more elaborate than the action of a pianoforte.
A swell pedal was also provided, and if moved in one direction the brilliancy and intensity of the colour is increased throughout the whole of the length of the scale, if in the other, the colour effect is made more tender. Another stop enables either softened or "staccato" productions of the colour upon the screen to be given.
It is, of course, quite clear that, in order to use an instrument provided with a keyboard like that just described, it is necessary to devise some method of musical notation. Any absolutely new method would bring with it various difficulties, the foremost among them being the necessity for the executant to learn the new method, and for any composer in mobile colour also to be familiar with it. It would
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