To confirm _both_ the foregoing admonitions, I must now inform you, that,
having in these parts two Lodgings, the one at _Oxford_, which you know
stands in a bottom by the _Thames_ side, and the other at a place four
miles thence, seated upon a moderate _Hill_, I found, by comparing two
_Baroscopes_, that I made, the one at _Oxford_, the other at _Stanton St.
Johns_, that, though the former be very good, and have been noted for such,
during some years, and the latter was very carefully fill'd; yet by reason,
that in the _Higher_ place, the incumbent part of the _Atmosphere_ must be
lighter, than in the _Lower_, there is almost {183} always between 2 and 3
Eights of an Inch difference betwixt them: And having sometimes order'd my
servants to take notice of the Disparity, and divers times carefully
observ'd it my self, when I pass'd to and fro between _Oxford_ and
_Stanton_, I generally found, that the _Oxford Barometer_ and the _other_,
did, as it were by common consent, rise and fall together so, as that in
the former the _Mercury_ was usually 3/8 higher, than in the latter.

Which Observations may teach us, that the Subterraneous steams, which
ascend into the Air, or the other Causes of the varying Weight of the
_Atmosphere_, do, many times, and at least in some places, uniformly enough
affect the Air to a greater height, than, till I had made this tryall, I
durst conclude.

But, as most of the _Barometricall_ observations are subject to exception,
so I found the formerly mentioned to be. For (to omit lesser variations)
riding one evening from _Oxford_ to _Stanton_, and having, before I took
horse, look't on the _Baroscope_ in the former of these 2. places, I was
somewhat surprised, to find at my comming to the latter, that in places no
farther distant, and notwithstanding the shortness of the time (which was
but an hour and a half, if so much) the _Barometer_ at _Stanton_ was short
of its usual distance from the _other_, near a quarter of an _Inch_,
though, the weather being fair and calm, there appear'd nothing of manifest
change in the Air, to which I could adscribe so great a Variation; and
though also, since that time, the _Mercury_ in the two Instruments hath,
for the most part, proceeded to rise and fall as before.

And these being the only Observations, I have yet met with, wherein
_Baroscopes_, at some _Distance of Place_, and _Difference of Height_, have
been compar'd (though I cannot now send you the Refl