in. As if, for instance, I have found by Observation, that the
Buble, I employ, (and one may have divers Bubles of several sizes, that the
one may repaire any mischance, that may happen to another) weigh'd just a
Drachme, when the _Mercurial_ Cylinder was at the height of 291/2 inches
(which in some places I have found a _moderate_ altitude;) and that the
Addition of the 16th part of a gr. is requisite to keep the Buble in an
_AEquilibrium_, when the _Mercury_ is risen an 8th, or any determinate part
of an inch above the former station: When I come to another place, where
there is a _Mercurial_ Barometer, as well freed from Air as mine (for that
must be supposed) if taking out my _Scale_ instrument, it appeare to weigh
precisely a Drachme, and the _Mercury_ in the Baroscope there stand at just
291/2 inches, we may conclude the Gravity of the Atmosphere not to be
sensibly unequal in both those two places, though very distant. And though
there be no Baroscope there, yet if there be an additional weight, as for
instance, the 16th part of a Grain requisite to be added to the Buble, to
bring the scales to an _AEquilibrium_, it will appear that the Air at this
second place is, at that time {239} so much heavier, than the Air of the
former place was, when the _Mercury_ stood at 291/2 inches.

But in making such comparisons, we must not forget to consider the
Situation of the several places, if we mean to make Estimates not only of
the weight of the Atmosphere, but of the weight and density of the Air.
For, though the Scales wil shew (as has been said) whether there be a
difference of weight in the Atmosphere at the two places; yet, if one of
them be in a Vale or bottom, and the other on the top or some elevated part
of a Hill, it is not to be exspected, that the Atmosphere, in this latter
place, should gravitate as much, as the Atmosphere in the former, on which
a longer Pillar of Air does lean or weigh.

And the mention, I have made of the differing Situation of Places, puts me
in mind of something, that may prove another use of our _Statical_
Baroscope, and which I had thoughts of making tryal off, but was
Accidentally hindred from the opportunity of doing it. Namely, that by
exactly poysing the Buble at the foot of a high Steeple or Hill, and
carrying it in its close Frame to the top, one may, by the weight requisite
to be added to Counterpoise there to bring the Beam to its Horizontal
position, observe the difference of the