made the Air so heavy
as to buoy up the Buble; but did not learn, that that mist had any sensible
operation on it.

_Fourthly_, By reason of the difficulties and casualties, that may happen
about the procuring and preserving such large and light Bubles, as I have
been lately mentioning; it may in some cases prove a convenience to be
inform'd, That I have sometimes, instead of one sufficiently large Buble,
made use of two, that were smaller. And, though a single Buble of competent
bignes be much preferable, by reason that a far less quantity and weight of
Glass is requisite to comprise an equal capacity, when the Glass is blown
into a single Buble, than when it is divided into two; yet I found, that
the employing of two instead of one, did not so ill answer my
exspectations, but that they may for a need serve the turn instead of the
other; than which they are more easier to be procured; And if the Ballance
be strong enough to bear so much Glass, without being injur'd: by employing
two or a greater number of large Bubles, the effect may be more
conspicuous, than if only a single Buble (though a very good one) were
employed.

This instrument may be much improved by divers Accommodations, As

_First_, There may be fitted to the _Ansa_ (or Checks of the Ballance) an
Arch (of a Circle) divided into 15. or 20. deg. (more or less, according to
the goodness of the Ballance) that the Cock resting over against these
Divisions, may readily {236} and without Calculation shew the quantity of
the Angle, by which, when the scales propend either way, the Cock declines
from the Perpendicular, and the beam from its Horizontall parallelism.

_Secondly_, Those, that will be so curious, may, instead of the Ordinary
Counterpoise (of Brass) employ one of Gold, or at least of Lead, whereof
the _latter_ being of equal weight with Brass, is much less in Bulk, and
the _former_ amounts not to half its bigness.

_Thirdly_, These parts of the Ballance, that may be made of Copper or
Brass, without any prejudice to the exactness, will, by being made of one
of those Mettals, be less subject, than Steel, (which yet, if well hardned
and polish'd, may last good a great while) to rust with long standing.

_Fourthly_, Instead of the scales, the Buble may be hung at one end of the
Beam, and only a Counterpoise to it at the other, that the Beam may not be
burthen'd with unnecessary weight.

_Fifthly_, The whole instrument, if placed in a small Frame, lik