The accidental colour of bluish green is red.
The accidental colour of of blue is orange.
The accidental colour of of yellow is violet.
The accidental colour of of white is black.
(The law of an accidental colour is this—The accidental colour is always half the spectrum. Thus, if we take half the length of the spectrum by a pair of compasses, and fix one leg in any colour, the other leg will hit upon its accidental colour.)
N. B. The spectrum means the seven colours—Red, orange, yellow, green, blue, indigo, and violet, divided into seven equal bands, and placed side by side in the order just mentioned.
CHAPTER XXVIII.
SOUND.
Q. What is sound?
A. The vibration of some sonorous substance produces motion in the air called sound waves, which strike upon the drum of the ear, and give the sensation of sound.
Q. What are musical sounds?
A. Regular and uniform successions of vibrations, which are always pleasing to the ear.