f i6oi ) 
a. — a rrr. 2$>'whicli 'X ^ giv--, . yD Cubic TncheSj which ' 
■ X 25.} 19.6 Grains. .So tfi^it dds Barofcope when the 
is loweft, is more exacr iitairilie comnion 126 Times, 
fuppofing the Body immersM afreftwhen the y is fo low. 
Next while t!»e y is very low, fupppfe the Top of 
the Body deprefs'd 4 Inches under WateV ; therefore 9 
— F + 4'-- 402.^, the- reft are as before, f c—- 67424, , 
then c&will be 1.9: but before, while the Top of the Bo- 
dy was .at the Surface, c6 was 2. 59. Therefore the Diffe- 
rence 69 X Tubers Area 2^ gives i »38 Cube-inches, whick 
X 25J gives g49 Grains, and fo much the Barofcope is 
heavier when the Top jc;^ is 4 Inches under Water, 'of 
which comes to the fame, fuppofing that y at 28, and 
xm at the Surface; this Barofcope by the afcending : 
h Inch will become heavier 5.49 Grains. The Pipe's Car 
pacity in 4 Inches Altifude was i.457,from which take the 
abovefaid i.?8, the refidue ^^^^ .©77, which x 25J gives 
19 Grains in 4 Inches ; fo that the Pipe will fuftain the 
Birofcope, and alfo 44 when the $ is ^ok high, and but 
19 Grains when the $ is 28 high. The fewer Grains dif- 
ference there are in its finking, thro' 4 Inches, the more 
nice the Barofcope will be. 
There where the Thread cufs the Surface of dh§ 
Water, is form'd a Bubble^ tlierefore this Bubble while y 
the Inftrument finks in Water 4 Inches, which is all the 
room that I give it, the Bubble moves on the 2 Diago- 
nal Threads 20 feches, it follows therefore that 120 
Grains difference would make the Bubble walk over 
120 Inches, if the Threads were lb long, but as 'it has 
been above calculated, about 120. Grain* difference of 
Weight of the Inftrument is producM by fo much , 
of the Alteration of the Air, as would make the ^ 
of the common Barofcope i^Inch: therefore when the 
afcends tt Inch, the Bubble of this new Barofcope 
afGends 120 . Inches-^: therefore this, new Barofcope:: is 
more e^d than the Common Barofcope by about 1200 • 
times. Ob- ^ 
