destitute both of a Compass and the sight of the Celestial guids, we might indeed, by chance, Steer directly towards our desired Port, but ’tis a thousand to one but we miss our aim.  But to proceed, we may hence also give a plain reason, how the Air comes to be darkned by clouds, &c. which are nothing but a kind of precipitation, and how those precipitations fall down in Showrs.  Hence also could I very easily, and I think truly, deduce the cause of the curious sixangular figures of Snow, and the appearances of Haloes, &c. and the sudden thickning of the Sky with Clouds, and the vanishing and disappearing of those Clouds again; for all these things may be very easily imitated in a glass of liquor, with some slight Chymical preparations as I have often try’d, and may somewhere else more largely relate, but have not now time to set them down.  But to proceed, there are other bodies that consist of particles more Gross, and of a more apt figure for cohesion, and this requires somewhat greater agitation; such, I suppose [Mercury], fermented vinous Spirits, several Chymical Oils, which are much of kin to those Spirits, &c.  Others yet require a greater, as water, and so others much greater, for almost infinite degrees:  For, I suppose there are very few bodies in the world that may not be made aliquatenus fluid, by some or other degree of agitation or heat.

Having therefore in short set down my Notion of a Fluid body, I come in the next place to consider what Congruity is; and this, as I said before, being a Relative property of a fluid, whereby it may be said to be like or unlike to this or that other body, whereby it does or does not mix with this or that body.  We will again have recourse to our former Experiment, though but a rude one; and here if we mix in the dish several kinds of sands, some of bigger, others of less and finer bulks, we shall find that by the agitation the fine sand will eject and throw out of it self all those bigger bulks of small stones and the like, and those will be gathered together all into one place; and if there be other bodies in it of other natures, those also will be separated into a place by themselves, and united or tumbled up together.  And though this do not come up to the highest property of Congruity, which is a Cohaesion of the parts of the fluid together, or a kind of attraction and tenacity, yet this does as ’twere shadow it out, and somewhat resemble it; for just after the same manner, I suppose the pulse of heat to agitate the small parcels of matter, and those that are of a like bigness, and figure, and matter,