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).