That Part of any neighbouring Building will appear the most confused, which is seen at the greatest Distance from the Earth; The Reason is, that there being more Dense, Cloudy Air between the Eye and the Ridge of the Building, than between the said Eye, and the bottom of the Building, the Image of the latter, must be more weakened, and disordered in its Passage, than that of the former. Nor must it be forgotten, that a Tower, whose Sides are Parallel, being seen at a Distance, and in a Foggy Air, will appear narrower and more contracted, as it approaches nearer its Basis; This happens, because, as we have already shewn, the Air becomes more Gross, as it is nearer the Earth, and more White, as it becomes more Gross; and because every obscure Object, appears smaller, as the Ground on which it is seen, is more White: For the Medium being Whiter, near the Foot, than the Top of the Tower, it follows, that the Building, on account of its Obscurity, must appear smaller, and narrower, towards its Extreme, than towards its Upper Parts.