For an Object, if seen at the same Distance _along_ the Ground, will appear less as it rises above it; and least in the Zenith; as the Sun and Moon, at Setting or Rising, appear _large and oval_; but at their greatest Elevation, are _small_ and _round_: because being seen, when passed out of a Medium impregnated with Vapours, which in some Measure intercept the Rays of Light: for the +fainter+[50] a distant Object appears, the _greater_ it is apprehended to be.[51] Possibly indeed an Object at the same Distance, if brighter at one Time than another, will _contract the Pupil_ in Proportion to its Brightness: which may have the same Effect, as if the Object had made a _smaller_ Miniature on the Retina; and will regularly strike the Mind with an Idea of _Magnitude_, _only_ equal to its corresponding _Contraction_; i.e. less, when the Object is bright, and greater when faint. 225. If a like Reasoning be applied to the Ascent of Balloons; and it be said that they do not rise so high as is imagined, because their Magnitude is diminished, merely from being elevated into a Portion of the Atmosphere _least_ impregnated with Vapours; it will follow, that to a Spectator in the Balloon; known Objects on the Surface of the Earth below,—being seen from a rarer into a denser Medium, also into one which contains a great Quantity of Vapours;—shoud appear _larger_, than when seen along the Ground, at a Distance equal to its Height in the Balloon: all which is contrary to Matter of Fact: particularly if the Barometer gives a proper Estimate of the Height, of which there is little Doubt: a proper Allowance being made, _in certain Cases_, on Account of the Refraction: for, as before mentioned, (Section 44) Objects seen from the Balloon at a Mile and Half _barometric_ Height, continued, with invariable Uniformity, to suggest the Idea of at least seven Miles. 226. By a general Comparison of Enclosures, and of separate Buildings when they coud be distinguished from the Balloon above the Region of Cloud, with the most distant Extremities, (on the horizontal Level) of Fields or Houses situated along the Sides of Hills or Mountains, at a known Distance by Miles, making Allowance for their being seen in a straight Line;—the latter seemed at least five Times _larger_ than the _former_: supposing them at equal Distances. To give an Instance. Supposing the most distant Extremities of a known Building or Enclosure, situated on the Side of a Hill or Mountain, presented a Miniature of a _familiar_ Magnitude to the Eye of the Spectator on the Ground, at the known Distance of a Mile and Half; the same Object when seen from the Balloon at the same _barometric_ Height, appeared full five Times less. This Comparison was made by Memory, the Morning after the Excursion, tho’ suggested while in the Balloon, from the wonderful Minuteness of all Objects then presented to the Eye.