illuminated by them all, and therefore will appear coloured. And
particularly at P, where the outmost violet-making Rays fall alone, the
Colour must be the deepest violet. At Q where the violet-making and
indigo-making Rays are mixed, it must be a violet inclining much to
indigo. At R where the violet-making, indigo-making, blue-making, and
one half of the green-making Rays are mixed, their Colours must (by the