made, as for example, in the selection of house furnishings. For this purpose disks of the top are combined at home to produce the desired colors to match the wood finishings and papers or draperies in a partially completed room, the top being used as a guide in preliminary selections of additional materials from the stores.
If a number of colors are required it is convenient to use several combinations of disks, each set being slightly gummed together. In this way standards for various colors with a top spindle for rotation in the salesroom may be carried in a very small space.
As every competent artisan must understand the use for which each implement is designed, in order to secure the best results with it, possibly a brief explanation of the principles on which the colors in the Bradley Educational Colored Papers are selected and classified may be of value. In the sample books of these colored papers there are four sections. The first section of the book, following the title leaf called "Pure Spectrum Scales" consists in part of the six standard colors, red, orange, yellow, green, blue and violet, with two intermediate hues between each two standards, which eighteen colors form the central vertical column in the Chart of Pure Spectrum Scales shown on Page 41.
In addition to these eighteen normal spectrum colors, there are two tints and two shades of each, thus producing eighteen spectrum scales of five tones, in which the normal colors as indicated in the central column aim to be the purest possible pigmentary expressions of the spectrum colors represented.
In determining the number of colors to adopt in the preparation of the papers enough have been selected to furnish types of all the colors in the spectrum, and also the hues between red and violet, but at the same time the number has been so restricted as to secure a reasonably simple nomenclature of the intermediate hues. A hue of a color is defined as the result of
