79). But several circumstances
concurring to form the judgment we make on the magnitude of distant
objects, by means of which they appear far larger than others, whose
visible appearance hath an equal or even greater extension; it follows
that upon the change or omission of any of those circumstances which are
wont to attend the vision of distant objects, and so come to influence
the judgments made on their magnitude, they shall proportionably appear
less than otherwise they would. For any of those things that caused an
object to be thought greater than in proportion to its visible extension
being either omitted or applied without the usual circumstances, the
judgment depends more entirely on the visible extension, and consequently
the object must be judged less. Thus in the present case the situation of
the thing seen being different from what it usually is in those objects
we have occasion to view, and whose magnitude we observe, it follows that
the very same object, being an hundred feet high, should seem less than
if it was an hundred feet off on (or nearly on) a level with the eye.
What has been here set forth seems to me to have no small share in
contributing to magnify the appearance of the horizontal moon, and
deserves not to be passed over in the explication of it.
74.
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