Every obscure Object, will appear so much the more Clear, and Bright, as it is further removed from the Eye; of course, therefore, the same Object will appear so much the more obscure, as it is seen at a less Distance: Hence it follows, that the lower Parts of an Object, seen in a thick Air, will seem further removed, than its Top; so that the bottom of a Mountain, will in appearance be further Distant from the Eye, than its Summet; and yet in Reality it is the nearest.