You are in the right, Sir, _said I_, but there's something wonderful in this which to many People appears a Paradox, _viz._ That if you take one of those Pieces of Ordnance so common with us, I mean a Cannon, levell'd at one of the highest Towers, and if at the very Instant of discharging it, a Bullet be let fall of the same Form and Size as that which the Cannon is charg'd with, notwithstanding the one is shot a Mile off, and the other falls down limply by a perpendicular Line, yet they will both come to the Ground at the same Instant. Indeed, _said the King_, that is surprizing, and I own, I should never have thought it; but I see very plainly now, that it must needs be so, because tho' the Bullet is carry'd a great Way, nevertheless its Motion from Top to Bottom must have its Course, and be every whit as rapid.
Yet these fine Examples don't set me clear enough in the Point of the Earth's Motion. Pray, how comes it that so violent an Agitation does not shake it into a Million of Pieces? Well, Sir, _said I_, take a Confectioner's Vessel made of white Earth; let it be of a round Form, and the Sides low and perpendicular to the Bottom. Put into it a Thimblefull or two of clear Water, and in this Water a small Quantity of the Filings of Copper, fine Sand, and the Grating of red Wax; and to supply the Place of Glass, of which you have none in this Country, cover the Vessel with a Lid very close, then cement it with a little Potter's Clay, and put it upon an Axis, to which you shall give Motion. When this Vessel has been turn'd about a little, if you take off the Lid, which was only plac'd on to hinder the Water from going out during its Agitation, you will see that all the Parts of the Matter put into it stick to the Sides of the Vessel. An evident Proof that if the Heavens turn'd which are here represented by these Sides, the Earth would necessarily be forc'd to quit its present Situation, and range itself against their concave Superficies or their Extremities. And another undeniable Proof which confirms the former, is, that if the Whirl be stopp'd, so that the Firmament or the Side of the Ship turns no more, the Water, which continues its Motion, and by consequence departs in Proportion, from the Centre of the Vessel which contains it, forces the Particles of Copper, Sand, and Wax to quit the Sides to which they stuck so fast, and to approach to the Centre where they form a round Mass, the lowest Region of which is Copper, the second Sand, and the last Wax. From hence it appears, that if the subtile Matter which encompasses the Earth be put in Agitation, 'tis sufficient to oblige all the Terrestrial Parts to rendezvous in one Globe towards their Centre: Which likewise shews us by the way, that 'tis impossible for a Stone cast into this subtile Matter, to rest in it one Moment, but must for the same Reasons abandon the Aerial Region, and repair to other Bodies of its own Species, in which properly consists Gravitation.