ascent, or descent, of _Mercury_: This Cylinder I, is movable on a very
small Needle, on the end of which is fixt a very light Index KL, all
which are so pois'd on the Axis, or Needle, that no part is heavier
then another: Then about this Cylinder is wound a small Clew of Silk,
with two small steel Bullets at each end of it GH; one of these, which
is somewhat the heavier, ought to be so big, as freely to move to and
fro in the Pipe F; by means of which contrivance, every the least
variation of the height of the _Mercury_ will be made exceeding visible
by the motion to and fro of the small Index KL.

But this is but one way of discovering the _effluvia_ of the Earth mixt
with the Air; there may be, perhaps many others, witness the _Hygroscope_,
an Instrument whereby the watery steams volatile in the Air are discerned,
which the Nose it self is not able to find. This I have describ'd in the
following Tract in the Description of the Beard of a wild Oat. Others
there, are, may be discovered both by the Nose, and by other wayes also.
Thus the _smoak_ of burning _Wood_ is _smelt_, _seen_, and sufficiently
_felt_ by the eyes: The _fumes_ of burning _Brimstone_ are _smelt_ and
discovered also by the destroying the Colours of Bodies, as by the
_whitening of a red Rose_: And who knows, but that the Industry of man,
following this method, may find out wayes of improving this sense to as
great a degree of perfection at it is in any Animal, and perhaps yet
higher.

'Tis not improbable also, but that our _taste_ may be very much improv'd
either by _preparing_ our taste for the Body, as, after eating _bitter_
things, _Wine_, or other _Vinous liquors_, are more sensibly tasted; or
else by _preparing_ Bodies for our tast; as the dissolving of Metals with
acid Liquors, make them tastable, which were before altogether insipid;
thus _Lead_ becomes _sweeter_ then Sugar, and _Silver_ more _bitter_ then