Levity

²⁵ Aerostatics is the species of gravity that depends entirely on the apparatus of siphons, pumps, and baroscopes if Elater [elasticity/spring force] is added.

Whatever stupendous things are performed with exhausted and compressed air.

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Heavy things remain in suspension, and heavy things are raised upward, not from a “fear of a vacuum” (metu Vacui)..

…otherwise they could be raised to infinity, which experience refutes, but only until there is equilibrium with the aerial cylinder of the entire atmosphere.

For when water does not follow in a pump, it will follow the aerial cylinder equal to the width of the pump’s piston, or it must be compressed, or raised so far into the liquid aether from its own sphere as is the length of the pump.

Because only that much space in the pump is left as a vacuum, or certainly greatly exhausted, even if the most subtle aether enters it.

The ratio of the baroscope is similar.

²⁶ But from where does air rush into exhausted vessels with such force?

I ask in the same way: if you place a closed vessel in the middle of water and then open it with a large hole, why will the water rush in?

By the force (nisu) of its own gravity.

Therefore, the same applies to air.

Water, however, rushes in more slowly and not without resistance, because the air which has a difficult exit must be expelled.

But air rushing into a vacuum, which is full of aether thrust into that place by force, is not only not impeded by the aether, but is even helped;

Because the aether, collected there in a pool beyond its usual manner, is impeded in its circulation and cannot exit, even if pores are open.[cite: 1] For although a vacuum is given, a great vacuum is not given: the place deserted by the air must therefore be replenished.

Therefore, the GRAVITY of the aerial cylinder and the ELATER, or the force of the aether dispersing itself into its proper circulation, concur![cite: 1]

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²⁷ The same reasoning applies to compressed air** collected as happens in loading pneumatic guns; for that phenomenon cannot be explained by the gravity of the air, but must therefore be explained by Elatere [elasticity], or the “appetite” for expanding itself.

This effort of expansion does not come from the air, but from the aether: for when air is compressed, the aether is squeezed out of it by many strokes, exactly as juice is from bodies in a mortar.

Once an opening is made, the aether—by the speed of its circulation which was previously disturbed and is now returning to order—enters again with the greatest force and scatters the air into its former rarity.

But why is the circulation thus disturbed? Because when air is exhausted, aether collects in a vessel in a quantity greater than is just; conversely, when air is compressed, the expressed aether is in a quantity greater than is just outside the vessel.

But that quantity of aether, greater than is just, hinders the circulation of the aether around the center of the earth, where the circulation is nearer to the center: because the nearer the circulation is to the center, as it is with us, the smaller the circles are, and thus all things must be more constricted.

Hence, wherever you transfer an exhausted or distended vessel, even if you go a thousand leagues away (see below § 48), if you remain only in the same Circle, or at approximately the same distance from the center of the earth, there will persist (indeed, if you move closer to the center, it will be increased) the effort of the aether to restore its circulation to the proper density.

Nor does it matter that we feel no constriction of air or aether around an exhausted vessel; for…

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…this happens for the same reason that prevents divers from feeling the weight of the sea, and us from feeling the motion of the aether, due to the mutual resistance of parts in a liquid, or the effort supported from both sides, which holds stones together in arched work and generally in spherical things.

Nor does it seem probable what the most diligent Boyle thought: that the parts of air have the likeness of a fleece or springs so as to restore themselves when compressed, unless that is held from an abstract Theory of motion: nothing, however bent, will restore itself by its own force.

Nor would there be such a great force in the elasticity of air—which we certainly feel to be the greatest of the powers known in nature thus far—if only the shaggy parts of the air were compressed; nor would the impetus be perpetually increased by increased compression or exhaustion, unless the state of the system itself were disturbed.

²⁸ This is the reason for Exhalations** being raised upward against natural gravity.

The sea, as Becher ingeniously thinks, perpetually distills its more bituminous and heavier part through the spongy bottom toward the center of the earth, or into a certain interior receptacle or universal estuary of our globe.

There, this sulfurous and bituminous mass having been digested and as if fermented, it emits through the earth vapors—that is, things rarer and therefore lighter than what the state and circulation of that sphere, closer to the center and thus denser, carries: from which [vapors] those that are aqueous, being subtler, light, and empty, go out higher…

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…they go out, and are partly resolved into springs, captured by suitable silt as if in an alembic, or they depart through an open exit into the air and constitute meteors[cite: 1].

²⁹ They also carry a certain subtle unctuosity or sulfur with them into the air.

The more unctuous part, intercepted either by stones or by that superior garden soil, goes there into metals, and here—with the addition of sublimation by the sun—into herbs, trees, fruits, and seeds.

I do not doubt with Hobbes, Derkennius, and Vossius that most springs arise from those mountain cisterns and collections of snow or rain.

Nevertheless, I think we must entirely agree with the Chemists, Brother Basil, Groschedelius, and Helmontius, that some are owed to subterranean vapors, from which also all mineral virtues of waters, and other specific powers of simples, are to be sought.

Since the sun and air, the universal agents and patients, are varied if you add the state of the underlying earth, whether the light is now closer and direct, or now more oblique and remote.

³⁰ Thus far concerning the phenomena of the whole globe;** now we must come to the appearances of species, which nevertheless arise mostly from the phenomena of the globe[cite: 1].

Furthermore, the phenomena of species are either sensible qualities or motions: even if all those qualities are insensible motions.

Sensible qualities are either sight, or hearing, or smell, or taste, or touch.

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The qualities of sight are Light and Colors.

Light is a very swift rectilinear motion of the aether toward the sense, propagated everywhere around every sensible point.

The Cartesian “propensity toward motion” is not sufficient because every propensity toward motion that is not followed by motion does not last beyond a moment (add above section 23 and below section 57).

Light is either that primigenial light in the sun (of which in sections 4 and 5), or second-born; and that is either original or imitated.

Original light is in the fire generated among us, which occurs from aether explosively heaped up by the rupture of innumerable bubbles (of which soon). Imitated light is in mirrors, and in things which collect rays during a long period in the open air, such as the Bolognian Stone and the firefly.

Some things produce light through digestion, fermentation, or internal motion, and from there—if strong enough—they produce either light or fire sensible to sight alone, as in rotting wood; or even common fire, as accumulated wet hay does.