and without Calculation ftiew the quantity of the Angle, by 
which, when the kales propend either way, the Cock declines, 
from the Perpendicular, and the beam from its Horizontal! pa- 
rallelifm. 
Secondly , Thofe, that will be fo curious, may, inftead of the 
Ordinary Counterpoife (of Brafs ) employ one of Gold 3 or at 
leaft of Lead, whereof the latter being of equal weight with 
Brafs, is much Iefs in Bulk, and the former amounts not to half 
nsbignefs. 
Thirdly , Thefe parts of the Ballance, that may be made of 
Copper or Brafs, without any prejudice to the exadtnefs, will, . 
by being made of one of thofe Mettals, be lefs fubjea:, than 
Steel, (which yet, if well hardned and poliflfd, may laft good a 
great while ) to ruft with long (landing. 
Fourthly , Inftead of the fcales, the Buble may be hung at one 
end of the Beam, and only a Counterpoife to it at the other, that 
the Beam may not be burthend with unneceftary weight. 
Fifthly, The whole inftrument, if placed in a fmall Frame, 
like a fquare Lanthorn with Glafs-windows, and a hole at the 
top for the Commerce of the internal and external Air, will be 
more free from duft, aud irregular agitations ; to the latter of 
which, it will otherwife be fometimes incident. 
Sixthly , This inftrument being accommodated with a light 
Wheele and an Index ( fuch as have been applyed by the excel- 
lent Dr. Chr. JVrent o open Weather glades, and by the inge- 
nious Mr. Hoe\to Barofcopes ) may be made to fhew much more 
minute variations, than otherwife. 
? Seventhly , And the length of tfie Beam, and exquificnefs of 
the Ballance, may eafily, without any of the foregoing helps 
(and much more with them) make the inftrument farexadter, 
than any of thofe, I was reduced to employ. And to thefe 
Accommodations divers others may be fuggefted by a farther 
confideration of the nature of the thing, and a longer praifti ce. 
Though infomerefpe&s this ^ta^WBarofcope be inferior 
to the Mercurial j yet in others it has its own advantages and 
conveniencies above it. 
And 1/ It confirms ad ocuhm our former Docftrine, that the 
railing and riling of the Mercury depends upon the varying 
weight of the Atmolpherej fince in this Barofcope it cannot 
be 
