4. That in the Ascension of Water in Pumps, &c. there needs nothing to raise the Water, but a Competent weight of an External Fluid.
5. That the pressure of an External Fluid is able to keep an Heterogeneous Liquor suspended at the same height in several Pipes, though these Pipes be of very different Diameters.
6. If a Body be placed under Water, with its uppermost Surface parallel to the Horizon; how much Water soever there may be on this or that side above the Body, the direct pressure susteined by the Body (for we now consider not the Lateral nor the Recoyling pressure, to which the Body may be exposed, if quite environed with Water) is no more, than that of a Column of water, having Horizontal Superficies of the Body for its Basis, and the Perpendicular depth of the Water for its height.
And so likewise,
If the Water, that leans upon the Body, be contained in Pipes open at both ends, the pressure of the Water is to be estimated by the weight of a pillar of Water, whose Basis is equal to the lower Orifice of the Pipe (which we suppose to be parallel to the Horizon) and its height equal to a perpendicular, reaching thence to the top of the Water; though the Pipe be much inclined towards the Horizon, or though it be irregularly shap'd, and much broader in some parts, than the said Orifice.
7. That a Body, immersed in a Fluid, sustains a Lateral pressure from the Fluid; and that increased, as the depth of the immersed Body, beneath the Surface of the Fluid, increaseth.
8. That Water may be made as well to depress a Body lighter than it self, as to buoy it up.
9. That, whatever is said of Positive Levity, a parcel of Oyl lighter than Water, may be kept in Water without ascending in it.
10. That the cause of the Ascension of Water in Syphons, and of its flowing through them, may be explicated without having a recourse to Nature's abhorrency of a Vacuum.