produces much compound shadow.
The effect of light at different distances.
182.
OF THE SHADOW CAST BY A BODY PLACED BETWEEN 2 EQUAL LIGHTS.
A body placed between 2 equal lights will cast 2 shadows of itself in the direction of the lines of the 2 lights; and if you move this body placing it nearer to one of the lights the shadow cast towards the nearer light will be less deep than that which falls towards the more distant one.
Further complications in the derived shadows (183-187).
183.
The greatest depth of shadow is in the simple derived shadow because it is not lighted by either of the two lights a b, c d.
The next less deep shadow is the derived shadow e f n; and in this the shadow is less by half, because it is illuminated by a single light, that is c d.
This is uniform