I347

Among Bodies seen in a Fog, a Cloud, Dense Air, Vapour, Smoke, or only at a Great Distance; that will appear the most Visible, and Distinct, which is the most elevated; And among Things equally elevated, that which is found in the obscurest Fog, will appear the most Obscure. Thus the Eye H, viewing A B C, three Towers of equal Height; it will see the Top C of the first Tower, as low as R; which is found immerged two Degrees within the Fog; and the Top of the Middle Tower B, will be seen in the same Fog; but then, so much of it as appears to the Eye H, will not be sunk beneath one Degree of Depth; so that the Top C, will appear more Obscure than the Top B; and that again, more obscure than the Top A.