Elements of Newtonian Philosophy

Subtle matter, vortices and the plenum must be rejected.

A wise reader, who has carefully observed these wonders of light, convinced by experience that no known impulse operates them, will no doubt be impatient to observe this new power of which we have spoken under the name of attraction, which acts on all other bodies more noticeably and in a different way than bodies act on light. Let names, once again, not frighten us; let us simply examine the facts.

I use the terms attraction and gravitation interchangeably, when speaking of bodies, whether they noticeably tend towards each other, or whether they turn in immense orbits around a common center, or whether they fall to the earth, or whether they unite to form solid bodies, or whether they round themselves into drops to form liquids[1].

All known bodies have weight, and absolute lightness has long been counted among the recognized errors of Aristotle and his followers.

Since the famous pneumatic machine was invented, it has become easier to know the weight of bodies.

When they fall in the air, the parts of the air noticeably retard the fall of those that have a lot of surface and little volume.

But in this machine deprived of air, bodies left to gravity fall according to their full weight.

The pneumatic machine, invented by Otto Guericke, was soon perfected by Boyle.

Then much longer glass receivers were made, which were completely purged of air.

In one of these long receivers, composed of four tubes, the whole together being 8 feet high, gold coins, pieces of paper, feathers were suspended at the top by a spring.

Good philosophers predicted that all this would fall at the same time.

Most asserted that the most massive bodies would fall much faster than the others.

They were very surprised when they saw.

In all the experiments, the gold, the lead, the paper and the feather fall equally fast.

Those who still believed Descartes’ plenum, for the alleged effects of subtle matter, could not explain it.*

If everything was a plenum, even if we granted them that movement could then exist (which is absolutely impossible), then this subtle matter would exactly fill the entire receiver.*

It would be there in as great a quantity as water or mercury that one would have put in it; it would at least oppose this so rapid descent of bodies; it would resist this large piece of paper, according to the surface of this paper, and would let the ball of gold or lead fall much faster; but this fall happens at the same instant:

Therefore there is nothing in the receiver that resists; therefore this so-called subtle matter can have no noticeable effect in this receiver; therefore there is another force that causes gravity.

In vain would one say that it is possible for a subtle matter to remain in this receiver, since light penetrates it; there is a great difference. The light that is in this glass vase certainly does not occupy a hundred-thousandth part of it.

But, according to the Cartesians, their imaginary matter must fill the receiver much more exactly than if I supposed it to be filled with gold: for there is a lot of emptiness in gold, and they admit none in their subtle matter.

By this experiment, the gold coin, which weighs one hundred thousand times more than the piece of paper, fell as fast as the paper: therefore the force that made it fall acted one hundred thousand times more on it than on the paper, just as my arm will need a hundred times more force to move a hundred pounds than to move one pound.

Therefore this power that operates gravitation acts in direct proportion to the mass of bodies. It does in fact act so much according to the mass of bodies, not according to the surfaces, that a piece of gold reduced to powder falls in the pneumatic machine as fast as the same quantity of gold spread in a sheet.

The shape of bodies changes nothing in their gravity here: this power of gravitation therefore acts on the internal nature of bodies, and not in proportion to the surfaces.

It has never been possible to respond to these pressing truths except by a supposition as chimerical as the vortices.

It is supposed that the so-called subtle matter that fills the entire receiver does not weigh: a strange idea that becomes absurd here. For it is not a question, in the present case, of a matter that does not weigh, but of a matter that does not resist.

All matter resists by its force of inertia. So if the receiver were full, whatever matter filled it would resist infinitely: this seems to be strictly demonstrated.

This power does not reside in the so-called subtle matter, which we will speak of in the next chapter; this matter would be a fluid. All fluid acts on solids in proportion to their surfaces; thus the vessel, presenting less surface with its bow, cleaves the sea which would resist its sides. Now, when the surface area of a body is the square of its diameter, the solidity of this body is the cube of this same diameter: the same power cannot act at once in proportion to the cube and the square; therefore gravity, gravitation is not the effect of this fluid.

Moreover, it is impossible for this so-called subtle matter to have on one side enough force to precipitate a body from 54,000 feet high in one minute (for such is the fall of bodies), and on the other to be powerless enough not to be able to prevent the pendulum of the lightest wood from rising from vibration to vibration in the pneumatic machine, whose imaginary matter is supposed to exactly fill the entire space.

If an impulse that was the cause of the gravity of bodies towards a center, in a word the cause of universal gravitation, of attraction, were ever discovered, this impulse would be of an entirely different nature than the one we know.

Here then is a first truth already indicated elsewhere, and proved here:

There is a power that makes all bodies gravitate in direct proportion to their mass.*

A body is heavier than another because it has more mass, more matter for the same size.

Thus, gold weighs more than wood, because there is much more matter and less emptiness in gold than in wood.

Descartes and his followers maintain that:

• a body is heavier than another without having more matter*
• there is a great vortex of subtle matter around our globe

This great circulating vortex:

• drives all bodies towards the center of the earth, and
• makes them experience what we call gravity.

They have not given any proof of this assertion.*

There is not the slightest experiment, not the slightest analogy in the things we know a little about, which could found a slight presumption in favor of this vortex of subtle matter;

Tthus, for the sole reason that this system is a pure hypothesis, it must be rejected. It is, however, for this sole reason that it has been credited.

This vortex was conceived without effort, a vague explanation of things was given by pronouncing this word “subtle matter”.

When the philosophers felt the contradictions and absurdities attached to it, they thought of correcting it rather than abandoning it.

Huygens and so many others made a thousand corrections to it, the insufficiency of which they themselves admitted.

But what will we put in the place of the vortices and subtle matter?

This all-too-common reasoning is what most strengthens men in error and in the wrong party.

We must abandon what we see to be false and untenable, both when we have nothing to substitute for it and when we have the demonstrations of Euclid to put in its place.

An error is neither more nor less an error, whether it is replaced or not by truths: should I admit the horror of a vacuum in a pump, because I would not yet know by what mechanism water rises in this pump?

The plenum and vortices of subtle matter do not exist.

Thus this whole system, based on these imaginations, is only an ingenious novel without plausibility.