the
difference of the Bore, or other circumstances of the Tube, may cause the
alteration; mine being a taller Tube, and a bigger Bore, than his.) And
upon like reason, as his stands higher than mine; so another less cleansed
from Air, may at the same time be considerably lower, and consequently
under 28. Inches at the lowest.

In _thick foggy_ weather, I find my Quicksilver to rise; which I adscribe
to the heaviness of the Vapours in the Air. And I have never found it
higher, than in the foggy weather above-mentioned.

In _Sunshiny_ weather it riseth also (and commonly the clearer, the more;)
which, I think, may be imputed _partly_ to the Vapors raised by the Sun,
and making the Air heavier; and _partly_ to the Heat, increasing the
Elastick or Springy power of the Air. Which latter I the rather add,
because I have sometimes observed in Sunshiny weather, when there have come
Clouds for some considerable time (suppose an hour or two) the Quicksilver
has fallen; and then, upon the Suns breaking out again, it has risen as
before.

In _Rainy_ weather, it useth to fall (of which the reason is obvious,
because the Air is lightned, by so much as falls:) In _Snowy_ weather,
likewise, but not so much as in _Rain_. And sometimes I have observed it,
upon a _Hoar-frost_, falling in the night.

[Sidenote: * _The Author of these Observations intends hereafter more
particularly to observe, _from what points_ those Winds blow, that make the
Quicksilver thus subside._]

For _Windy_ weather, I find it _generally_ to fall; and that more
universally, and more discernably, than upon Rain: (which I attribute to
the Winds moving the Air _collaterally_, and thereby not suffering it to
press so much _directly_ downwards: the like of {171} which we see in
swimming, &c.) And I have never found it lower than in high Winds.*

I have divers times, upon discerning my Quicksilver to fall without any
visible cause at home, looked abroad; and found (by the appearance of
broken Clouds, or otherwise) that it had rained not far off, though not
with us: Whereupon, the Air being then lightened, our heavier Air (where it
rained not) may have, in part, discharged it self on that lighter.

* * * * *

_A more particular Account of those Observations about _Jupiter_, that were
mentioned in _Numb. 8_._

Since the publishing of _Numb._ 8. of these _Transactions_, where, among
other particulars, some short Observations were se