Page:A color notation (Munsell).djvu/102

 fields of weak chroma. For instance, a spot of strong reddish purple is balanced and enhanced by a field of gray-green. So an amethyst pin at the neck of the girl’s dress will appear to advantage with the gown, and also with the Leghorn straw. But a large field of strong color, such as a cloth jacket of reddish purple, would be fatal to the measured harmony we seek.

(166) This use of a small point of strong chroma, if repeated at intervals, sets up a notion of rhythm; but, in order to be rhythmic, there must be recurrent emphasis, “a succession of similar units, combining unlike elements.” This quality must not be confused with the unaccented succession, seen in a measured scale of hue, value, or chroma.

(167) A sheet of paper large enough to hide the color sphere may be perforated with three or more openings in a straight line, and applied against the surface, so as to isolate the steps of any se- quence which we wish to study. Thus the sequence given in paragraph 160—$Y 8⁄7$, $G 6⁄5$, $BG 4⁄3$—may be changed to bring it on the surface of the sphere, when it reads $Y 8⁄3$, $G 6/5$, $BG 5⁄5$. A mask with round holes, spaced so as to uncover these three spots, relieves the eye from the distraction of other colors. Keeping the centre spot on green, the mask may be moved so as to study the effect of changing hue or value of the other two steps in the sequence.

(168) The sequence is lightened by sliding the whole mask upward, and darkened by dropping it lower. Then the result of using the same intervals in another field is easily studied by moving the mask to another part of the solid.

(169) Change of interval immediately modifies the character of a color sequence. This is readily shown by having an under-mask, with a long, continuous slit, and an over-mask whose per-