Chap. CCLXI.—Of Colours in Shadow.
It happens very often that the shadows of an opake body do not retain the same colour as the lights. Sometimes they will be greenish, while the lights are reddish, although this opake body be all over of one uniform colour. This happens when the light falls upon the object (we will suppose from the East), and tinges that side with its own colour. In the West we will suppose another opake body of a colour different from the first, but receiving the same light. This last will reflect its colour towards the East, and strike the first with its rays on the opposite side, where they will be stopped, and remain with their full colour and brightness. We often see a white object with red lights, and the shades of a blueish cast; this we observe particularly in mountains covered with snow, at sun-set, when the effulgence of its rays makes the horizon appear all on fire.