( 1^00 ) 
Put / — *247 « c ^ 172 . d~ 16^ . 2 2s above, only, 
change F, put F 4^7.3^ that is, fuppofe the Body funk in 
Water 4 Inches lower ; In this Cafe — 208, therefore 
^ ct — - . 64 which multiplycd into ^ » ^ 1.28 
Cubic-inches, which x 25 J gives 524 Grains, and fo- 
much the Body'^s Top x m being fun!< 4 Inches 
under Water, the Body becomes heavier, than while' 
x m was at the Surface of the Water. Thcretore this 
1.28 divided by the aforefaid Depth 4 gives .32 the A- 
rea of the Top Pipe fuch as would baltance or buoyc 
up' the Body at any Depth. Striftly fpeaking the Pipe 
fhould be gradually bigger upward in order to fuftain the 
Inftrument at any Depth, but as to Senfe 'tis Cylindrical, 
andits Circumference " 2.005. But for that the lead: Al- 
teration of the Air would make the Body's Top xm in 
that cafe pafs thro' the 4 Inches (which 4 Inches I fup- 
%ok all the Variety of Depth that the Inftrument has roomi 
given it in the Bucket to afcend or defcend ) therefore the 
Pipe is made a fmall matter bigger, ( 'viz. ) its Circum- 
fer-ence is 2a 4 ; whereby the Pipe, , according as the. Body 
finks more, gives more refiftance to the defcending Bo- 
dy. The Pipes Area is.j64j : Therefore the Capacity of 
the Pipe in 4 Inches Altitude is — i .457/ But as abovefaid 
togivejuftly no refiftance, its Capacity fhould be 1.28^ 
Therefore this 1.28 taken frdmi.457,'leaves . 177 the actu- 
al refiftance in 4 Inches depth, viz. (.177^253 — )44 
Grains. 
But this refiftance will not be the fan:ie inall weather% 
in order therefore to calculate what it will be when the 
^ of the common Barofcope is very low : For example, but 
28 Inches high — 392 of Water j / muft be fuppos^d ~ 
^i)2y therefore F ^^f-^ h-^ 39^-3^ and the reft as 
before; vjj^. d^j6^j f c = 67^24. F //^ 645^229. 
Thence by thQ aforefaid Equation a=-, 2.J9? 'YhQtchrQ 
a ^ 2^84^ 
