mes many daies together, if the Air so long retain'd the
same measure of gravity; and then (upon other changes) the Buble would
regain an _aequilibrium_, or a preponderance; so that I had oftentimes the
satisfaction, by looking first upon the _Statical_ Baroscope (as for
distinctions sake it may be call'd) to foretell, whether in the _Mercurial_
Baroscope the Liquor were high or low. Which Observations though they hold
as well in Winter, and several times in Summer (for I was often absent
during that season) as the Spring, yet the frequency of their Vicissitudes
(which perhaps was but accidental) made them more pleasant in the latter of
these seasons.

So that, the matter of Fact having been made out by variety of repeated
Observations, and by sometimes comparing severall of those new _Baroscopes_
together, I shall add some of those Notes about this Instrument, which
readily occur to my memory, reserving the rest till another opportunity.

And _First_, if the ground, on which I went in framing this _Baroscope_, be
demanded, the answer in short may be; 1. That, though the Glass-buble, and
the Glass-counterpoise, at the time of their first being weigh'd, be in the
Air, wherein they both are weigh'd, exactly of the same weight; yet they
are nothing near of the same bulk; the Buble, by reason of its capacious
cavity (which contains nothing but Air, or something that weighs less than
Air) being perhaps a hundred or two hundred times (for I have not
conveniency to measure them) bigger than the Metalline counterpoise. 2.
That according to a _Hydrostatical_ Law (which you know I have lately had
occasion to make out) If two Bodies of equal gravity, but unequal bulk come
to be weigh'd in another _Medium_, they will be no longer {234}
equiponderant; but if the new _Medium_ be heavier, the greater Body, as
being lighter in _Specie_, will loose more of its weight, than the lesser
and more compact; but if the new _Medium_ be lighter than the first, then
the bigger Body will outweigh the lesser; And this disparity, arising from
the change of _Medium's_, will be so much the greater, by how much the
greater inequality of bulk there is between the Bodies formerly
equiponderant. 3. That, laying these two together, I consider'd, that
'twould be all one, as to the effect to be produced, whether the Bodies
were weighed in _Mediums_ of differing gravity, or in the same _Medium_, in
case its (_specifick_) gravity were considerably alter'd: And