By how much a transparent Medium found between the Eye, and its Object, is more spacious, and its interposition greater, by so much the more will the natural Colour of the Object, be transformed into that of its Medium.

When an Object is so disposed between the Eye and the Light, as that it is found in the Central Line, passing between the Centres of the Light, and of the Eye; that Object must remain entirely dark, and devoid of Light.