The spacing problem consists in the detection and correction of errors of allocation in surface-color space of the regular 1929 Munsell samples. This amounts to the adjustment of imperfections in a real chromatic skeleton of 400 units so that it will more properly fit into an ideal chromatic body. For the last five years various observers have been making visual estimates of the color spacings and the accumulated data have been summarized and are presented herewith in tabular form. These data will provide a psychological basis for defining smooth contours of Munsell hue, value, and chroma in terms of the 1931 I.C.I. colorimetric coordinate system. The plan is to present those contours in the final report. The present report includes charts of a preliminary smoothing of chroma based on the earlier visual estimates.
SIDNEY M. NEWHALL, "Preliminary Report of the O.S.A. Subcommittee on the Spacing of the Munsell Colors," J. Opt. Soc. Am. 30, 617-645 (1940)