I349

When the Sun is near his setting, the Shadows projected on White Walls, open to the Air, will always appear of the Colour of Azure: This follows, from what we have already shewn, viz. That the Surface of every Opake Body partakes of the Colour of its Object; whence, the Whiteness of the Wall, being altogether destitute of Colour, must assume those of its Objects; which, in this Case, are the Sun, and the Heavens: and since the Sun in his Evenings Visit to the Horizon, appears Reddish, and the Heavens Azure; And since those Places where the Shadows are found, are out of the reach of the Sun; we having elsewhere proved, that no luminous Body has ever seen the Shadow of any Body illuminated by it; 'Tis Obvious, that the Shadow of the Heavens, projected on the White Wall, will appear Azure; and further, that the Ground of that Shadow, being illumined by the Sun, will appear Reddish, in Conformity to the Redness of its Luminary.