Page:Philosophical Transactions - Volume 001.djvu/247

 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, like a square Lanthorn with Glass-windows, and a hole at the top for the Commerce of the internal and external Air, will be more free from dust, audand [sic] irregular agitations; to the latter of which, it will otherwise be sometimes incident.

Sixthly, This instrument being accommodated with a light Wheele and an Index (such as have been applyed by the excellent Dr. Chr. Wren to open Weather glasses, and by the ingenious Mr. Hook to Baroscope) may be made to shew much more minute variations, than otherwise.

Seventhly, And the length of the Beam, and exquisitness of the Ballance, may easily, without any of the foregoing helps (and much more with them) make the instrument far exacter, than any of those, I was reduced to employ. And to these Accommodations divers others may be suggested by a farther consideration of the nature of the thing, and a longer practice.

Tough in some respects this Statical Baroscope be inferior to the Mercurial; yet in others it has its own advantages and conveniences above it.

And 1.It confirms ad oculum our former Doctrine, that the falling and rising of the Mercury depends upon the varying weight of the Atmosphere; since in this Baroscope it cannot Rh