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Hydrostatics;

XIII. When any Body is immersed ina Fluid, it loses jujl so much of its Weight asis equal to the Weight of an equal Bulk of theFluid ; but the Weight lofl by the Body is

gain'd

will then hold the great Weight in Equilibria , and ifever so little more be blown in it will raise it; for inthat Case the Air will press upwards with a greaterForce than that of the Weight downwards.

8. If 500 Cubic Inches of Air were blown into theInstrument it would sustain 30000 Ib. and to on. Butin such Cases we must suppose the Parts EF sufficientlystrong to bear such a Pressure from within; for sincethe Air is a Fluid it presses every Way equally. Nowbecause the Bore of the Tube is small (suppose the 100thPart of a square Inch) a Person blowing through thesame would meet with no more Resistance than thePressure of the Air on the Area of the Bore, whichwhen the Air is of a double Density, or when 25OCubic Inches are crowded in, will be but -,Vo ofa Pound, which may be easily overcome by theForce of the Muscles in blowing, especially if we use aStop-cock to sliut off the Air in the Tube every Timewe take in fresh Air to -our Mouths.

9. If the Top of the Instrument DC were fix’d, and,a Wire passing thro’ the Tube GH were fix’d to theBottom, and suspended at the End of a Balance, then ifthe Bottom be nicely balanced by Weights in the Scaleof the other End, and after that Water pour’d in till theTop and Bottom were separated to their utmost Di-stance ; to balance this Water will require one PoundWeight for every Inch in Height in the Vessel, and itwill after that require one Pound Weight for everyInch that it rises in the Tube, which plainly sliews thatthe Force of Fluids is always proportional to the Height,and not the Quantity of the Fluid. Note, I have sup-posed in this Article that the Diameter of the Vessel issix Inches, as before in Art. 5. Another remarkable 1Instance of this Hydrostatic Paradox, I shall give whenI come to consider the Su/imtning of an heavy Body in a

2 lighter-