( 340 ) 
Explication of the Figures. 
In Fig.i-AB, the 
Stem or Pipe. 
C Ejthe two parts 
of the Ball foderM 
together. 
BCDE,theBaU it 
felf. 
F, the Screw. 
G 5 the Stirrup „ 
fomewhat reprefen- 
ted out of Its place* 
H, the Mark to 
which a , Copper- 
plate, of equal 
weight in the Air 
with the Guiny, de- 
prelTes the Inftru- 
ment. 
I , the Mark to 
which a true Gui- 
ny finks it. 
Fig,2.is the Screw 
by it felf, to be put 
upon or taken from 
theffliort) undcr- 
moft ftemoftheln- 
flrument. 
Fig.3. the perfora- 
ted plates of Lead 
or other metal,to be 
put on as ballaft up- 
on the undermofl 
flem. 
Fi th d 
moft Stem with a perforated Ballaft-plate put upon ir. * ^'^' 
Fig.5, the Stirrup, that may be employed inftead of a Screw. 
Tig.6. A B C, the Glafs-inftrument. 
D D p, the Coin hanging at the bottom of it, and fupported by four 
horle-hairs,or flender ftnngs of filk. 
l}rl-^{^: ^I'r ""'^"™ftStemof the Glafs-Inftrument, to which, being 
itreight and foI,d,a Screw is faftncd on with horfe-hair,orotherwife. 
t>g.8.A B C D,thefmall Glafs-Inftrument foreftimating the fpccifique 
gravuy of Liquors Cof which an account may be expedled in our next. ) 
n t 4 a' '"'^ "^P'°y^'^ Ballall to fink it in 
anereaed pofture. The 
