Chap. CCXIII.—Of Reverberation.
Reverberations are produced by all bodies of a bright nature, that have a smooth and tolerably hard surface, which, repelling the light it receives, makes it rebound like a foot-ball against the first object opposed to it.
Chap. CCXIV.—Where there cannot be any Reverberation of Light.
The surfaces of hard bodies are surrounded by various qualities of light and shadow. The lights are of two sorts; one is called original, the other derivative. The original light is that which comes from the sun, or the brightness of fire, or else from the air. The derivative is a reflected light. But to return to our definition, I say, there can be no reflexion on that side which is turned towards any dark body; such as roofs, either high or low, shrubs, grass, wood, either dry or green; because, though every individual part of those objects be turned towards the original light, and struck by it; yet the quantity of shadow which every one of these parts produces upon the others, is so great, that, upon the whole, the light, not forming a compact mass, loses its effect, so that those objects cannot reflect any light upon the opposite bodies.
