First, When a house is seen over a very broad river by a person standing
on low ground, who sees nothing of the river, nor knows of it
beforehand; the breadth of the river being hid from him, because the
banks seem contiguous, he loses the idea of a distance equal to that
breadth; and the house seems small, because he refers it to a less
distance than it really is at. But, if he goes to a place from which the
river and interjacent ground can be seen, though no farther from the
house, he then perceives the house to be at a greater distance than he
imagined; and therefore fancies it to be bigger than he did at first;
although in both cases it appears under the same Angle, and consequently
makes no bigger picture on the retina of his eye in the latter case than
it did in the former. Many have been deceived, by taking a red coat of
arms, fixed upon the iron gate in _Clare-Hall_ walks at _Cambridge_, for
a brick house at a much greater distance[45].
[Sidenote: Fig. XII.]
Secondly, In foggy weather, at first sight, we generally imagine a small
house, which is just at hand, to be a great castle at a distance;
because it appears so dull and ill defined when seen through the Mist,
that we refer it to a much greater distance than it really is at; and
therefore, under the same Angle, we judge it to be much bigger. For, the
near object _FE_, seen by the eye _ABD_, appears under the same Angle
_GCH_, that the remote object _GHI_ does: and the rays _GFCN_ and _HECM_
crossing one another at _C_ in the pupil of the eye, limit the size of
the picture _MN_ on the retina; which is the picture of the object _FE_,
and if _FE_ were taken away, would be the picture of the object _GHI_,
only worse defined; because _GHI_, being farther off, appears duller and
fainter than _FE_ did. But if a Fog, as _KL_, comes between the eye and
the object _FE_, it appears dull and ill defined like _GHI_; which
causes our imagination to refer _FE_ to the greater distance _CH_,
instead of the small distance _CE_ which it really is at. And
consequently, as mis-judging the distance does not in the least diminish
the Angle under which the object appears, the small hay-rick _FE_ seems
to be as big as _GHI_.
[Sidenote: Fig. IX.