This reconcile* apparent contradictions in earlier theories and is now generally accepted.

GRAPHIC PRESENTATION

A. Maxwell Discs of Slit Paper or Cardboard.

s the idea of the spectrum band of colors invaded the field of practical use, it was made into a circle by adding the purple hues between blue and red. for which there is no spectral wave length. Scientists and artists divided this circle of hues to suit their needs, usually at regular intervals around the circle, with complementary colors opposite each other. Complementary colors are those producing neutral gray when mixed in correct proportions. Unmixed they tend to intensify each other.

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Allcolor Company, New York City, "An Explanation and U«e of Allcolor Paperi." Courtesy of Munscll Color Company.

C. The Horizontal Scale of Chroma.

1. This shows the practical advantage in numbering chroma steps beginning at gray.

2. Hues differ in the number of their chroma steps.

3. As new pigments of greater intensity become available, new chroma steps can be added. Some hues have acquired four new chroma steps since tliis system came into use.

Millon Bradlry Co. New York City

B. Color Top.

1. Maxwell discs of slit paper or cardboard, for studying primary and other color relations, can be obtained with small color tops, and larger color wheels, from Milton Bradley Co. and the Abbott Educational Co., New York City.

I. These discs arc easily made from water-color paper painted with tempera or show card colors. They should be slit from the edge to the center, so that they can overlap as desired when superimposed.