EFFECT OF ELEMENTARY SENSATIONS ON ONE ANOTHER.
Here is a lantern throwing a steady light through a large tube. (See illustration below, the right hand group.) By transparent slides of colored glass or gelatine, the light may be made of any color. At the end of the tube is a box, like a camera. The operator covers his head with a cloth, and observes the color of the light as it shines from the tube through, or on, a tiny hole in the dark box. The size of the hole can be varied by moving slides, worked by micrometer screws so fine that they measure the dimensions of the hole to the four-hundredth of an inch.
STUDYING THE EFFECTS OF SOUND AND OF ATTENTION ON COLORS.
The first step is to discover the “threshold” of each separate color. That means the smallest-sized hole through which each color can be distinguished. This varies for different colors. But now comes the interesting point. The size of the hole, for any given color seen, varies according to the nature of any sound heard at the same time. For instance, in order to distinguish a given red, the hole must be larger or smaller, in proportion as the pitch of a musical tone is lower or higher, fainter or stronger.
STUDYING THE EFFECTS OF COLORS ON JUDGMENTS OF TIME.
The above experiment is one in a system of investigations, intended to discover the laws by which the simplest sensations modify each other under the simplest conditions. These are laws as fixed as the laws of gravity, and, once determined, we may move on to study the combination of these elements into the higher thought processes.