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K. S. GIBSON AND D. NICKERSON
this relation all of the 1919 and 1926 data for the chromatic samples have been plotted on the (x, y)-diagram shown in Fig. 4. To assist in an evaluation of any consistent or erratic differences among the data two straight lines are plotted for each Munsell hue designation: First, a dashed line passing from the 5/5 point for each of the five principal hues through the point representing I.C.I. Illuminant C and on to the complementary; and second, a continuous line passing from the same 5/5 point through the point (DM) which results from disk mixture of these five principal hues in equal proportions.[1]
To assist the reader to correlate the plotted points representing the experimental data with the proper pair of these dominant wave-length lines, each pair of points (45° and diffuse illumination) is connected by a light continuous line to the respective line of dominant wave-length, using the lines through DM for this purpose. The points chosen for the contact of the line- ↑ Having first multiplied each (X, Y, Z)-triad by factors to make Y=0.25, as suggested by Tyler and Hardy, reference 11.