the wheel and sufficiently accurate for all practical purposes, while it is a very fascinating occupation for child or adult.
In the use of disks for analyzing colors it must be remembered that every material color is some quality of some color in the spectrum circuit, and therefore may be matched with not more than two standard disks, either alone or with white or black or both. If more than two color disks, besides white and black, are used they will neutralize each other more or less, and a neutral gray or a gray and some spectrum color will be the result. For example, 'if yellow and blue in nearly equal parts are introduced in connection with red and orange, the yellow and blue being nearly complimentary to each other will produce practically a neutral gray, and the result will be the same as if only red, orange, white and black were used.
Owing to the recent advances in the art of dyeing there are some textile goods which are too intense in color to be exactly imitated by the disk standards, but this fact need not prevent
a practical analysis of such colors, because by very slightly reducing with white the color to be examined the same color is retained, the modification making it, of course, somewhat lighter. Fig. 64, showing a small circle representing a disk of the material mounted on thick paper, illustrates this statement. Suppose we have a piece of rich brown cloth, so intense in color that when red, orange and black are combined in the proportions
