han when in the meridional position:
and yet it is esteemed greater in the former than in the latter. Herein
consists the difficulty, which doth vanish and admit of a most easy
solution, if we consider that as the visible moon is not greater in the
horizon than in the meridian, so neither is it thought to be so. It hath
been already shown that in any act of vision the visible object
absolutely, or in itself, is little taken notice of, the mind still
carrying its view from that to some tangible ideas which have been
observed to be connected with it, and by that means come to be suggested
by it. So that when a thing is said to appear great or small, or whatever
estimate be made of the magnitude of any thing, this is meant not of the
visible but of the tangible object. This duly considered, it will be no
hard matter to reconcile the seeming contradiction there is, that the
moon should appear of a different bigness, the visible magnitude thereof
remaining still the same. For by sect. 56 the very same visible
extension, with a different faintness, shall suggest a different tangible
extension. When therefore the horizontal moon is said to appear greater
than the meridional moon, this must be understood not of a greater
visible extension, but a of greater tangible or real extension, which by
reason of the more than ordinary faintness of the visible appearance, is
suggested to the mind along with it.

75. Many attempts have been made by learned men to account for this
appearance. Gassendus, Descartes, Hobbes, and several others have
employed their thoughts on that subject; but how fruitless and
unsatisfactory their endeavours have been is sufficiently shown in THE
TRANSACTIONS,[Phil. Trans. Num. 187. p. 314] where you may
see their several opinions at large set forth and confuted, not without
some surprize at the gross blunders that ingenious men have been forced
into by endeavouring to reconcile this appearance with the ordinary
Principles of optics. Since the writing of which there hath been published
in the TRANSACTIONS [Numb. 187. P. 323] another paper relating to the same
affair by the celebrated Dr. Wallis, wherein he attempts to account for
that phenomenon which, though it seems not to contain anything new or
different from what had been said before by others, I shall nevertheless
consider in this place.

76. His opinion, in short, is this; we judge not of the magnitude of an
object by the visual angle alone, but by the