did every body I spake with {55}
about it, that there is yet another irregularity in the Tides, which never
fails, and is no less extraordinary, than what I have been mentioning:
which is, That, whereas between the _Vernal_ and _Autumnal Equinoxes_, that
is, for six Moneths together, the Course of irregular Tides about the
Quartermoons, is, to run all day, that is, twelve hours, as from about 91/2
to 91/2, 101/4 to 101/4 _&c. Eastward_, and all night, that is, twelve hours
more, _Westward_: during the other six Moneths, from the _Autumnal_ to the
_Vernal Equinox_, the Current runs all day _Westward_, and all Night
_Eastward_.

Of this, though I had not the opportunity to be an Eye-witness, as of the
other, yet I do not at all doubt, having received so credible Information
of it.

To penetrate into the _Causes_ of these strange Reciprocations of the
Tides, would require exact descriptions of the Situation, Shape, and Extent
of every piece of the adjacent Coasts of _Eust_ and _Herris_; the Rocks,
Sands, Shelves, Promontorys, Bays, Lakes, Depths, and other Circumstances
which I cannot now set down with any certainty, or accurateness; seeing,
they are to be found in no _Map_, neither had I any opportunity to survey
them; nor do they now occur to my Memory, as they did some years ago, when
upon occasion I ventured to make a _Map_ of this whole _Frith_ of
_Berneray_, which not having copied, I cannot adventure to beat it out
again.

* * * * *

__Monsieur Auzout_'s Judgment touching the Apertures of _Object-Glasses_,
and their _Proportions_, in respect of the several _Lengths_ of
_Telescopes_._

This Author, observing in a small _French Tract_ lately written by him to a
Countryman of his, Monsieur _L' Abbe Charles_; That great _Optick Glasses_
have almost never as great an _Aperture_ as the small ones, in proportion
to what they Magnifie, and that therefore they must be more dim; takes
occasion to inform {56} the _Reader_, that he hath found, that the
_Apertures_, which _Optick-Glasses_ can bear with distinctness, are in
about a _subduplicate proportion_ to their _Lengths_; whereof he tells us
he intends to give the reason and demonstration in his _Diopticks_, which
he is now writing, and intends to finish, as soon as his Health will
permit. In the mean time, he presents the _Reader_ with a _Table_ of such
_Apertures_; which is here exhibited to the Consideration of the Ingenious,
there be