ttentively consider the present _Figure_ of his
_Anses_ or _Ring_, to see whether the appearance be to him, as in this
_Figure_, and consequently whether he there meets with nothing, that may
make him think, that it is not _one_ body of a Circular Figure, that
embraces his _Diske_, but _two_.

And to the end that other Curious men, in other places might be engaged, to
joyn their Observations with him, to see, whether they can find the like
appearance to that, represented here, especially such Notches or
Hollownesses, as at A and B, it was thought fit to insert here the newly
related Account.

* * * * *

_A Relation of some _Mercurial_ Observations, and their Results._

Modern _Philosophers_, to avoyd Circumlocutions, call that Instrument,
wherein a Cylinder of Quicksilver, of between 28. and 31. Inches in
Altitude, is kept suspended after the manner of the _Torricellian_
Experiment, a _Barometer_ or _Baroscope_, first made publick by that Noble
Searcher of Nature, Mr. _Boyle_, and imployed by Him and others, to detect
all the minut variations in the Pressure and weight of the Air. For the
more {154} curious and nice distinguishing of which small changes, Mr.
_Hook_ in the _Preface_ to his _Micrography_, has described such an
Instrument with a _Wheel_, contrived by himself, and, by these two last
years trials of it, constantly found most exact for that purpose: which
being so accurate, and not difficult to be made, it were desirable, that
those who have a Genius and opportunities of making Observations of this
kind, would furnish themselves with such of these Instruments, as were
exactly made and adjusted according to the Method, delivered in the newly
mentioned place.

To say something of the Observations, made by this Instrument, and withal
to excite studious _Naturalists_ to a sedulous prosecution of the same, the
_Reader_ may _first_ take notice, that the lately named Mr. _Boyle_ hath
(as himself not long since did intimate to the Author of these _Tracts_)
already made divers Observations of this kind in the year 1659. and 1660.
before any others were publick, or by him so much as heard of; though he
has hitherto forborn to divulge them, because of some other Papers (in
whose Company they were to appear) which being hindred by other studies and
employments, he hath not as yet finished.

_Next_, that, besides several others, who, since have had the curiosity of
making such observat