This also gives us a probable reason of the so much admired Phaenomena, of the Oculus Mundi, an Oval stone, which commonly looks like white Alabaster, but being laid a certain time in Water, it grows pellucid, and transparent, and being suffer’d to lie again dry, it by degrees loses that transparency, and becomes white as before.  For the Stone being of a hollow spongie nature, has in the first and last of these appearances, all those pores fill’d with the obtunding and reflecting air; whereas in the second, all those pores are fill’d with a medium that has much the same refraction with the particles of the Stone, and therefore those two being contiguous, make, as ’twere, one continued medium, of which more is said in the 15. Observation.

There are a multitude of other Phaenomena, that are produc’d from this same Principle, which as it has not been taken notice of by any yet that I know, so I think, upon more diligent observation, will it not be found the least considerable.  But I have here onely time to hint Hypotheses, and not to prosecute them so fully as I could wish; many of them having a vast extent in the production of a multitude of Phaenomena, which have been by others, either not attempted to be explain’d, or else attributed to some other cause than what I have assign’d, and perhaps than the right; and therefore I shall leave this to the prosecution of such as have more leisure:  onely before I leave it, I must not pretermit to hint, that by this Principle, multitudes of the Phaenomena of the air, as about Mists, Clouds, Meteors, Haloes, &c. are most plainly and (perhaps) truly explicable; multitudes also of the Phaenomena in colour’d bodies, as liquors, &c. are deducible from it.

And from this I shall proceed to a second considerable Phaenomenon which these Diamants exhibit, and that is the regularity of their Figure, which is a propriety not less general than the former, It comprising within its extent, all kinds of Metals, all kinds of Minerals, most Precious stones, all kinds of Salts, multitudes of Earths, and almost all kinds of fluid bodies.  And this is another propiety, which, though a little superficially taken notice of by some, has not, that I know, been so much as attempted to be explicated by any.

This propriety of bodies, as I think it the most worthy, and next in order to be consider’d after the contemplation of the Globular Figure, so have I long had a desire as wel as a determination to have prosecuted it if I had had an opportunity, having long since propos’d to my self the method of my enquiry therein, it containing all the allurements that I think any enquiry is capable of:  For, first I take it to proceed from the most simple principle that any kind of form can come from, next the Globular,