S. Tolver Preston's Explosive Idea
E = mc2 and the Huyghens-Leibnitz Mass/Energy Identity as a Heuristic Principle in the Nineteenth Century

(Christopher Jon Bjerknes)


Abstract. In 1875, S. Tolver Preston published a prophetic treatise, which set forth his arguments for the existence of an aethereal medium in space. The title of this work is Physics of the Ether. Its purpose is to discredit the spiritualistic concept of "action at a distance" and to evince the irrationality of the principle of "potential energy", and replace these mythologies with "physical causes capable of rational appreciation." Among the many achievements of this heuristic masterpiece are Preston's arguments for atomic energy, the atomic bomb, a luminal speed for the propagation of gravity, and the heuristic principle that E = mc2.



Samuel Tolver Preston [b. 1844, was the son of Daniel Bloom Preston (b. 1807) and Mary Susannah Tolver] set forth arguments in the nineteenth century, which were to condition life in the twentieth century, and beyond. In an early attempt to apply Herbert Spencer's "Social Darwinism" in a constructive way (as opposed to the horrific racism it furthered), Preston argued for the collegiate education of females, on the grounds that it would strengthen the genetic stock of males and generally increase the intelligence of human beings.[1] This opposed the longstanding tradition that the Church is the bride of Christ, and is obedient; and, therefore, a woman must obey her husband and shun professional work. In a letter to Darwin, Preston professed rationalistic words to the effect of, "self-interest as a motive for conduct is a thing to be commended - and it certainly [is] I think ... the only conceivable rational motive of conduct: and always is the tacitly recognized motive in all rational actions."[2] Preston's equally pragmatic aether theories led him into diverse fields. For example, Preston speculated on the nature of "Free Will" and brain dynamics - another of his scientific challenges to the religious ontology and traditions pervasive in his time.[3]

Preston's profound physical insights were the result of a rational analysis of phenomena he conducted in the refined language and images of the eighteenth century homme d'esprit George-Louis Le Sage. Preston's work was in part a self-described scientific reaction to contemporary "theories of a vague nature" which proposed "phantom agencies" to account for known phenomena. His Physics of the Ether [4] is a scientific synthesis derived from the hypotheses that aether is rarified mass, mass, concentrated aether; and that aether particles must be in motion and this motion is conserved. For Preston, as for many of his contemporaries, all things are modes of motion. These premises evolve subtly into a definition of terms, identities, and mathematical expressions described in compelling prose, which assert, among other things, that energy is proportional to mass times the speed of light squared, yielding incredibly potent kinetic effects,

"165. To give an idea, first, of the enormous intensity of the store of energy attainable by means of that extensive state of subdivision of matter which renders a high normal speed practicable, it may be computed that a quantity of matter representing a total mass of only one grain, and possessing the normal velocity of the ether particles (that of a wave of light), encloses a store of energy represented by upwards of one thousand millions of foot-tons, or the mass of one single grain contains an energy not less than that possessed by a mass of forty thousand tons, moving at the speed of a cannon ball (1200 feet per second); or other wise, a quantity of matter representing a mass of one grain endued with the velocity of the ether particles, encloses an amount of energy which, if entirely utilized, would be competent to project a weight of one hundred thousand tons to a height of nearly two miles (1.9 miles)."
Towards a Comprehensive Theory of Dynamics
Based on Motion as a Unifying and Vivifying Cause

Preston set a high standard for his work, which many today would consider naïve, "there can exist but one correct method of viewing any subject or question whatever." Before we can come to understand Preston and evaluate the nature of his conclusions and determine his method for arriving at them, we should first explore the historical context, which led him to question the mythologies prevalent in his day, and to propose alternative points of view based on a Le Sagian materialism, which originally arose as a materialistic exposition on the Epicurean theory of "universal attraction".[5]

Le Sage argued that if space were to contain an extremely fine particulate aether of "ultramundane particles" moving at light speed in all directions, these particles would bombard bodies. In the case of a comparatively isolated body, the bombardment would, statistically, be even on all sides, and a sort of equilibrium pressure would result. However, bodies would cast "shadows" on other bodies by blocking out those "ultramundane" aether particles which strike them. This proposed shadowing effect would cause a net force of attraction between bodies, in conformity with Newton's inverse square law.

In Preston's day, as today, there was a lingering religious opposition to any such mechanistic exposition on the cause of gravity, which would obviate the governance and active intervention of God as the cause of gravity. Many, Roger Cotes, Richard Bentley and Voltaire, among them, considered the idea of "universal attraction" to be a scientific proof of the existence and active governance of God. Just as the Church had opposed any refutation of Aristotle's Physics and Metaphysics, religious extremists opposed and oppose any mechanistic exposition on a proposed cause of "mutual attraction". This corrupt attitude toward pure science, which is an offense against religious freedom, not an expression of it (Descartes, Huyghens and Leibnitz, who were vocal advocates of aethereal gravitational theories, were deeply religious men), is exemplified by Bentley's A Confutation of Atheism from the Origin and Frame of the World, written pursuant to Newton's letters,[6]

"And first as to that ordinary Cant of illiterate and puny Atheists [***] That such a mutual Gravitation or spontaneous Attraction can neither be inherent and essential to Matter; nor even supervene to it, unless impress'd and infused into it by a Divine Power. (3.) That though we should allow such attraction to be natural and essential to all Matter; yet the Atoms of Chaos could never so convene by it, as to form the present System: or if they could form it, it could neither acquire such motions, nor continue permanent in this state, without the power and Providence of a Divine Being."[7] This religious persecution had a chilling effect on research into the physical causes of gravity and magnetism. The subject became and remained largely taboo, with a few notable exceptions. Colin Maclaurin's writings evince how lightly one had (has) to tread when proposing a physical theory of gravity. He was a diplomatic apologist for such an approach: "14. As we cannot but conceive the universe, as depending on the first cause and chief mover, whom it would be absurd, not to say impious, to exclude from acting in it; so we have some hints of the manner in which he operates in nature, from the laws which we find established in it. Tho' he is the source of all efficacy, yet we find that place is left for second causes to act in subordination to him; and mechanism has its share in carrying on the great scheme of nature. The establishing the equality of action and reaction, even in those powers which seem to surpass mechanism, and to be more immediately derived from him, seems to be an indication that those powers, while they derive their efficacy from him, are however, in a certain degree, circumscribed and regulated in their operations by mechanical principles; and that they are not to be considered as mere immediate volitions of his (as they are often represented) but rather as instruments made by him, to perform the purposes for which he intended them. If, for example, the most noble phaenomena in nature be produced by a rare elastic aetherial medium, as Sir Isaac Newton conjectured, the whole efficacy of this medium must be resolved into his power and will, who is the supreme cause. This, however, does not hinder, but that the same medium may be subject to the like laws as other elastic fluids, in its actions and vibrations; and that, if its nature was better known to us, we might make curious and useful discoveries concerning its effects, from those laws. It is easy to see that this conjecture no way derogates from the government and influences of the Deity; while it leaves us at liberty to pursue our enquires concerning the nature and operations of such a medium. Whereas they who hastily resolve those powers into immediate volitions of the supreme cause, without admitting any intermediate instruments, put an end to our enquires at once; and deprive us of what is probably the most sublime part of philosophy, by representing it as imaginary and fictitious: by which means, as we observed above, they hurt those very interests which they appear so sanguine to promote; for the higher we rise in the scale of nature, towards the supreme cause, the views we have from philosophy appear more beautiful and extensive. Nor is there any thing extraordinary in what is here represented concerning the manner in which the Supreme Cause acts in the universe, by employing subordinate instruments and agents, which are allowed to have their proper force and efficacy; for this we know is the case in the common course of nature; where we find gravity, attraction, repulsion, &c. constantly combined and compounded with the principles of mechanism: and we see no reason why it should not likewise take place in the more subtile and abstruse phaenomena and motions of the system."[8] Preston courageously and unapologetically confronted the religious bias and dogma against mechanistic theories of gravitation. He cautions us to not "attach two ideas to [a] fundamental conception[.]" Motion is the sole cause, for Preston. He also notes, regarding theories of a vague nature, "that their very vagueness, in which their real weakness consists, is employed as a defence against argument: hence the long life of such theories." This is a reaction against the vague and "spiritualistic" notion of "action at a distance" as a "cause". The cause of gravity is to this day considered by some a divine mystery not meant to be understood by humankind.

Consider Cotes' preface to Newton's Principia, where he intimates that the search for a physical cause for gravity, as opposed to a blind faith in (mythological and numerological) theological forces, is heresy. Cotes, seemingly together with Newton, asserts that induction resolves gravity to the will of God as the ultimate cause of the phenomenon,

"Without all doubt this World, so diversified with that variety of forms and motions we find in it, could arise from nothing but the perfectly free will of God directing and presiding over all. [***] All sound and true philosophy is founded on the appearance of things; which if they draw us never so much against our wills, to such principles as most clearly manifest to us the most excellent counsel and supreme dominion of the All-wise and Almighty Being; those principles are not therefore to be laid aside, because some men may perhaps dislike them. They may call them, if they please, miracles or occult qualities; but names maliciously given ought not to be a disadvantage to the things themselves; unless they will say at last, that all philosophy ought to be founded in atheism. [***] He must be blind who from the most wise and excellent contrivances of things cannot see the infinite Wisdom and Goodness of their Almighty Creator, and he must be mad and senseless who refuses to acknowledge them.[9] Newton's distinguished work will be the safest protection against the attacks of atheists, and nowhere more surely than from this quiver can one draw forth missiles against a band of godless men."[10] Voltaire, also, threatened those who would attempt a Cartesian exposition on gravity, "The cause of this cause is among the Arcana of the Almighty. 'Procedes huc, et non amplius.' (Thus far shalt thou go, and no farther.)"[11] Preston's fundamental conception is that all things transform as modes of motion through the impact of particles. These hypothetical particles bear the measurable properties of inertia, momentum and energy, and "fill" an otherwise void cosmic "empty space". There is a tacit monadism lurking in Preston's ideas, which he leaves largely unexplored. He argues through induction that the gaseous nature of his aether filling "space" is self-evident and need not be explained in terms of frames of reference, or contained volumes, other than as ontological absolutes. It is this absolutism, which ultimately leads him to predict that E = mc2, as an absolute store of energy contained in material bodies, which can be put to work.

For Preston, as for Huyghens and Leibnitz, the identity between mass and energy is the mode of motion. He argues that "action at a distance" is an impossibility, which requires the "absurd postulate of an infinite velocity[.]" He further argues that the concept of "potential energy" is devoid of meaning, because it asserts energy without motion, and confuses terms by equating, in name only, one state with a completely different state. A living person can potentially die, and become a dead person, but such a fact does not render a living person, dead. The state of a mass in a field of force is not the same as the state of a mass in motion, in terms of the ability to do work. Should a field of force composed of a shower of aether particles impart motion to a body, then it is this conserved motion which is cause, not spiritual "potential" which is cause.

Preston substitutes the action of an intervening medium for the two myths of "action at a distance" and "potential energy", which he finds feed off of one another, the fall of one necessarily toppling the other. He attempts to logically prove that the conservation of energy is only satisfied by supposing that the aether is a gas of particles in linear motion, which expand to fill any contained volume. The "forces" of Nature result from contact with these moving particles of aether. The velocity of these particles cannot be infinite, for if it were, then the aether particle which causes the phenomena of gravity and magnetism would have to concurrently occupy the beginning, middle and end of its journey, an impossibility.

Preston induces the elasticity and speed of aether particles, which of logical and experimental necessity (by analogy to an aeriform medium) must be in motion, from the speed of light. He does not delve into the metaphysics of why his proposed aether particles move at light speed, but instead infers this speed as a logical necessity, his necessary singular exposition of the known phenomena, his ultimate generalization arrived at through induction from known experimental results.

We see here many of the elements of the theory of relativity, stated in scientific terms, as opposed to the metaphysics, which later replaced the scientific hypotheses of this aether theory. "Action at a distance" must occupy time, due to the fact it is through the action of an intervening medium that the effects known as "action at a distance" arise. This speed is the normal speed of aether particles, known through induction to approximate the speed of light - gravity propagates at the speed of light, a speed which nothing can exceed, for speed depends upon the size of a particle and an aether particle is perhaps the smallest fathomable subdivision of matter, and the fastest motion. Preston induces these Le Sagian ideas from the properties of light propagation. Le Sage simply wrote, "we assume for the [gravitational] corpuscles the velocity of light[.]"

From these basic inductions to general principles, Preston begins to synthesize these generalizations into fantastic and useful conclusions,

"The above deduction, as to the high speed of the ether particles in their normal state, throws at once a light upon the existence of a vast store of energy in space of a very intense character, competent to produce the most forcible observed molecular motions, such as the phenomena of chemical action, combustion, the explosion of gunpowder, and other remarkable cases of the development of motion or work, all such effects finding their explanation in an interchange of motion between the ether and the molecules of matter under special conditions[.]" The bombardment of aether particles flying about in space, each with great energy due to their high velocity, produces an enormous pressure in space. Taking note of the fact that the tensile strength of steel wire is enormous and again appealing to reason, Preston holds that matter cannot cohere with the immense force it does if it is simply composed of isolated masses suspended in empty space. There must be a "material agent" which causes this effect, which effect Preston attributes to a pressure differential, as a logical necessity, "As to the precise physical process by which a reduction of the pressure of the intervening medium can take place in the presence of vibrating matter, we shall reserve the consideration of this point for the present; but it may be noted that the inference is none the less essential, that a reduction of the ether pressure does take place in the presence of the opposed vibrating molecules of the wire, since there remains no other conceivable means of explaining in a realizable manner why these portions of matter (molecules), already completely disconnected from each other in the normal state of the wire, should require this enormous force to shift their positions in the act of breaking the wire, unless in this act there were something further to be accomplished than merely to change the positions of molecules in space. [A change in position of the wire itself, without breaking it, requires no such powerful force.]" Preston goes on to attribute the pressure differential to a rarefaction of the aether between vibrating bodies caused by "stationary waves" between them, "We have observed that a vibratory movement of matter, under such conditions that the waves are reflected and thereby stationary vibrations are formed in the medium, is well qualified to disturb the equilibrium of pressure of the medium," and makes clear that he does not see cohesion as the ultimate pressure differential between normal volume elements of aether and of vacuum; and he gives the example of chemical bonds as a state of pressure differential far exceeding the force of cohesion. His inferences again and again produce an increase in force commensurate with a reduction in scale. The subdivision results in the attenuation of matter into aether particles, as a limit. He sets a figure of, "500 tons per square inch as a limiting value for the ether pressure".

Again, there is no metaphysical attempt to delve into the cause of the normal velocity of aether particles, but Preston does tacitly and ontologically assume a quite vaguely defined frame of reference for this velocity. This ontological belief, and Preston's attitudes toward mechanics, truth, and his epistemological agenda, would today be considered by many to be naïve and circularly reasoned; but they nevertheless produced predictions which have been borne out by technological advances in the twentieth century; and one seriously doubts that these predictions would have arisen in relativity theory, other than as a thinly veiled repetition (without attribution) of the conclusions drawn by Preston, Olinto De Pretto [Editor's note: see for instance Umberto Bartocci, Albert Einstein e Olinto De Pretto: la vera storia della formula più famosa del mondo, Ed. Andromeda, Bologna, 1999; information on line: http://www.dipmat.unipg.it/~bartocci/listast.htm, points 9 and C] and others, through relativity theory's more complicated ontological fictions, which have no inductive justification, and which reify purely abstract conceptualizations of dimension. In contrast to relativity theory, Preston's ideas are based on quantifiable measurements, on measurable relations, ultimately resolved into the most scientific expressions of our empirical sensual experience, the sense of resistance to touch, which is "pressure" and "matter", as a measurable thing; and the separation of distance through time, which velocity constitutes a measurable relation. Preston proposes a dynamic "material agency", the aether.

Preston derives the density of the aether. This is quite significant to his later derivations of the store of energy contained in the density of matter, and the powerful effects which he predicts will occur should matter be subdivided into aether particles,

"In connection with this subject, it may be of great interest to contemplate the possibility of the following as a physical problem. If we suppose a given mass of matter and a given volume of space, the volume of the space being supposed vastly greater than that of the mass of matter. Then it becomes possible, by the subdivision of the this mass of matter (which may be readily conceived to carried out to any extent), to pervade the entire volume of the space with matter, or there is no limit to the degree of close proximity into which the particles of matter pervading this space may be brought by continuous subdivision, the approach of the particles going on continuously without limit as the subdivision progresses. Thus, with a given mass of matter there is no limit to the extent of space that may be pervaded by matter by continued subdivision, or there may be no appreciable portion of the vast volume of space but what contains myriads of particles of matter. The normal state of this finely subdivided matter may be conceived to be a state of motion or a state of rest; if a state of motion, then we may observe the physical possibility of the existence of a store of energy of an extreme intensity, and which, from the minuteness and small length of path of the moving particles, must be concealed; this motion being also necessarily attended by the production of an intense and at the same time evenly balanced pressure, the smoothness and uniformity of the pressure, and the consequent concealment of its existence from the senses, being more and more complete as the subdivision progresses." Preston concludes that the aether is made up of subdivided particles of matter, which conclusion is happily in agreement with the velocity and properties of light propagation. He infers a posteriori a relation between the subdivision of matter and an increase in the speed of particles, which ultimately results through the subdivision of mass in aether particles moving at or slightly above light speed. In a statement of the working principle of the atomic bomb, Preston avows, "If now we imagine, merely for illustration, each of these air molecules to be subdivided into a million parts, and that the speed of each component part has been increased a thousand times. The presence of the ether within the receiver may be left out of account for the present. Then by this imaginary process of subdivision, the mean distance of these parts of matter (which we shall term 'particles') would be so reduced as to bring these particles into closer proximity than the molecules of air outside the receiver (the mean distance of the particles of the subdivided matter being inversely as the cube root of the their number). The pressure against the interior of the receiver, which is as the square of the speed of the particles, would now be increased a million-fold; and yet this result is attained without any increase in the absolute value of the energy of each particle, for the energy has, by the reduction of mass, remained precisely the same for each particle as before, although the total energy has become vastly greater, this energy being now subdivided among a large number of particles, and the pressure maintained by a greatly increased number of moving particles.

We might imagine this process of subdivision, or this reduction of mass combined with increase of speed, to go on progressively, and thus the total energy would be continually increasing, and the mean distance and mean length of path of these small moving masses or particles would be continually diminishing, and therefore the concealment of this motion from the senses would be more and more complete. The pressure would continually rise in intensity, and at the same time become more even and perfectly balanced as the number of particles increased.

We might thus imagine this process to go on progressively, until at length the dimensions, mean distance, and speed of the ether particles themselves had been reached; or its possible thus step by step to arrive at a just conception of the wonderful intensity of the store of energy that is rendered physically practicable, and the high static value of the pressure that may be reached, under the simple mechanical conditions of an extensive subdivision of matter combined with a high speed."

The "speed of the ether particles" is that of a wave of light, and the "absolute value of the energy of each particle" when reduced to aether is mc2, which is described in Preston's prose in section 165 of his book, as quoted here above in the introduction. S. Tolver Preston provided a qualitative and quantitative theory, which set in motion the search for atomic energy and weaponry, a search which was ultimately successful. His contributions to science deserve far greater mention. Preston was indeed a man of science, who did not flinch when opposing the religious zealotry he confronted. We would do well to follow his example and oppose "theories of a vague nature" which propose "phantom agencies" like "space-time" and replace them with "physical causes capable of rational appreciation."



[1] S. T. Preston, "Evolution and Female Education", Nature, (23 September 1880), pp. 485-486; Revised, Original essays. I. On the social relations of the sexes. II. Science and sectarian religion. III. On the scientific basis of personal responsibility, with a reprint from an essay on "Evolution and female education," revised from Nature, September 23, 1880, Williams and Norgate, London, Edinburgh, (1884).

[2] S. T. Preston paraphrased in F. Darwin & A.C. Seward, Editors, More letters of Charles Darwin, Volume 2, Chapter 8, John Murray, London, (1903), p. 52, Letter 421.

[3] S. T. Preston, "On a Point Relating to Brain Dynamics", Nature, (13 May 1880), pp. 29-30; Responses by G. Romanes, Nature, Volume 22, p. 75, and W. C. Ley, Nature, Volume 22, (10 June 1880), p. 121; Reply by Preston, Nature, (10 June 1880), p. 121.

[4] S. T. Preston, Physics of the Ether, E. & F. N. Spon, London, (1875).

[5] G. L. Le Sage, read by P. Prevost to the Berlin Academy in 1782, "Lucrèce Neutonien", Nouveaux Mémoires de l'Académie royale des Sciences et Belles-Lettres de Berlin,Year 1782, (Berlin, 1784), pp. 404-427; reprinted in Notice de la Vie et des Écrits de George-Louis Le Sage, Chez J. J. Paschoud, Genève, (1805), pp. 561-604; English translation by C. G. Abbot with an introduction by S. P. Langley appears in: "The Le Sage Theory of Gravitation", Annual Report of the Board of Regents of the Smithsonian Institution Showing the Operations, Expenditures, and Condition of the Institution for the Year Ending June 30, 1898,(U.S.) Government Printing Office, Washington, (1899), pp. 139-160. W. Thomson, S. Tolver Preston, H. A. Lorentz, and J. J. Thomson, among many others, pursued Le Sage's shadow theory of ultramundane particles. Maxwell and Poincaré opposed it, on the basis that it would result in excessive heat accumulation.

[6] I. Newton, Four Letters from Sir Isaac Newton to Doctor Bentley containing Some Arguments in Proof of a Deity, London, (1756) [Editor's note: see also Episteme N. 5, March 2002]. Edward B. Davis has presented significant scholarship on Newton's religious views: "Newton's Rejection of the 'Newtonian World View': The Role of Divine Will in Newton's Natural Philosophy", Fides et Historia, Volume 22, Number 2, (Summer 1990), pp. 6-20; reprinted Science and Christian Belief, Volume 3, Number 1, (1991), pp. 103-117; reprinted with additions Facets of Faith and Science, Volume 3, University Press of America, Lanham, Maryland, (1996), pp. 75-96.

[7] R. Bentley, A Confutation of Atheism from the Origin and Frame of the World, Part 3, Phoenix, London, (1693), pp. 4, 20-21.

[8] C. Maclaurin, "Of the Supreme Author and Governor of the universe, the True and Living God", An Account of Sir Isaac Newton's Philosophical Discoveries, Book 4, Chapter 9, Patrick Murdoch, London, (1748), pp. 388-390.

[9] R. Cotes, in I. Newton, The Mathematical Principles of Natural Philosophy, London, (1729), from "THE PREFACE OF Mr. Roger Cotes", not paginated.

[10] R. Cotes, Cote's preface to the second edition of Newton's Principia. Sir Isaac Newton's Mathematical Principles of Natural Philosophy and his System of the World, University of California Press, Berkeley, Los Angeles, London, (1962), p. XXXIII.

[11] F. M. A. Voltaire, "On Attraction", Letters on England, Letter 15.

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[We believe it worthwhile to add an ending section about the important question: vis viva versus kinetic energy]

Clash of Leibnitz and Newton Space as Meta-Aether


There was in Preston's day an emerging rejection of the Newtonian ideas of mystical "force" as a cause of phenomena among "empty space". Fechner stated,

"All that is given is what can be seen and felt, movement and the laws of movement. How then can we speak of force here? For physics, force is nothing but an auxiliary expression for presenting the laws of equilibrium and of motion; and every clear interpretation of physical force brings us back to this. We speak of laws of force; but when we look at the matter more closely, we find that they are merely laws of equilibrium and movement which hold for matter in the presence of matter. To say that the sun and the earth exercise an attraction upon one another, simply means that the sun and earth behave in relation to one another in accordance with definite laws. To the physicist, force is but a law, and in no other way does he know how to describe it. . . All that the physicist deduces from his forces is merely an inference from laws, through the instrumentality of the auxiliary word 'force'." [12] T. H. Pasley, in 1835, averred, "Of the nature of matter the knowledge is limited to the principle of inertia. Matter being inert it can do nothing and bodies formed of inert matter are incapable of acting in any manner: the want of power cannot originate power: hence cause must consist in means independent of action by matter. Matter consisting in unorganized molecules, it appeared nothing out of reason to conclude that the whole and all things they go to form are inert. For if a body be broken its parts are inactive, and the body itself to be in an acting state requires to be impelled by means such as itself does not possess. The inertia of matter therefore is evident. Matter being inert it cannot either attract or repel. But then, how is universal gravitation, acknowledged by all the most learned of the world and demonstrated mathematically, to be set aside, and wherein is cause of it and attraction be rejected. The difficulty is as great as the Authorities who make no difficulty of supporting these principles and causes are exalted in fame. The greatest difficulty however lies in reconciling them with the Inert nature of Matter. Matter has no acting properties as it is essentially inert. Acting implies being in motion; motion requires physical impulse foreign to that which is made to act, and from the atoms of matter being unalterable, by nothing but physical impulse can they be affected, nor can the effect be other than motion. Wherefore, gravitating, and repelling are not properties of either matter or bodies. [***] In moral philosophy inertia means inferior ability and ability sluggishly exerted; in Physics it signifies no ability or power whatever. Making inertia a 'passive power' amounts to no power; power implies acting, passive power not acting or that can act, but power is never passive. Inertia being an 'inert force' is the same as force without force: 'vis inertiae' is the force of inactivity, the power of inability. All bodies are convertible into powers, but are such only while being made to act. To say a body 'resists' by means of its inertia, is making nothing a physical force. Who can conceive force at rest. Inertia causing 'an endeavour and perserverance in a body to continue in motion or at rest' is a contradiction in terms [***] Inertia is no cause, it is nothing active or passive. The resistance of a ponderable body at rest is caused by that which makes it ponderable. Inertia being nothing is productive of nothing; it may be said to be the zero of cause." [13] Pasley identified many of the fatal flaws in the Epicurean mythologies, for example, "[W]itness the Newtonian Theory of Gravitation, Attraction and Repulsion, which, it is said 'Newton has proved to the whole world direct and regulate the System.' But as gravitating, attracting and repelling cannot belong to inert bodies, formed as all are of inert matter, the adopted theory, in these respects, is utterly fallacious and untrue. Gravitating by the Planets of their own accord is as movement in the lifeless; attraction as the will of the dead; and repulsion as antipathy possessed by a stone. The whole of these and all such monstrocities have origin solely in the theory of Perception being rejected where most applicable, and in coupling Activity with Inertia." [14] Preston wanted to replace these myths with a physical agent, which obeyed the principle of the conservation of energy. Perhaps the most famous name associated with the principle of the conservation of energy, the foundation of Preston's natural philosophy, is Julius Robert Mayer. He sought a meaningful definition of the concept of "force" and this is likely why Preston, in working out the energy store in bodies through Joule's and Clausius' methods, deduced Leibnitz' vis viva, as opposed to kinetic energy,[16] as the absolute store of energy contained in mass. In 1807, Thomas Young defined "energy" in English as, "The term energy may be applied, with great propriety, to the product of the mass or weight of a body, into the square of the number expressing its velocity."[17] Mayer stated, in 1852, in an effort to provide a "generic conception of 'force,'" "On the other hand, the product of the pressure into the space through which it acts, or, again, the product - or half-product - of the mass into the square of the velocity, is named 'force.' In order that motion may actually occur, it is in fact necessary that the mass, whatever it may be, should under the influence of a pressure, and, in the direction of that pressure, traverse a certain space, 'the effective space' (Wirkungsraum): and in this case a magnitude which is proportional to the 'pushing force' and to the effective space, likewise receives the name 'force;' but to distinguish it from the mere pushing force, by which alone motion is never actually brought about, it is also called the 'vis viva of motion,' or 'moving force.' With the generic conception of 'force,' the higher mechanics, as an essentially analytic science, is not concerned. In order to arrive at it, we must, according to the general rule, collect together the characters possessed in common by the several species. As is well known, the definition so obtained runs thus - 'Force is every thing which brings about or tends to bring about, alters or tends to alter motion'. This definition, however, it is easy to see, is tautological; for the last fourteen words of it might be omitted, and the sense would be still the same. [***] If a mass M, originally at rest, while traversing the effective space s, under the influence and in the direction of the pressure p, acquires the velocity c, we have ps = Mc2. Since, however, every production of motion implies the existence of a pressure (or of a pull) and an effective space, and also the exhaustion of one at least of these factors, the effective space, it follows that motion can never come into existence except at the cost of this product, ps = Mc2. And this it is which for shortness I call 'force.'"[18] Preston focused on the notion of aethereal pressure (as opposed to mystical "forces" of gravitation and magnetism exerted upon a mass by a mass via "action at a distance") again and again in opting for the formulation of the absolute store of energy as E = mc2 , as opposed to E = ½ mv2. This is perhaps due to the fact that most of the writings on the principle of the conservation of force from the 1840's focused on Galilean-Leibnitzian style experiments with falling masses. Leibnitz' arguments for a conserved vis viva against Descartes' momentum were initially a posteriori and depended upon experiments of gravitation on the Earth. However, by 1875 it was an anomaly for Preston to not see the "transference of work" done by a body thrown upwards against the "resistance" of "gravity" as ½ mv2. Preston wrote, "26. In considering the high normal velocity of the ether particles, it is to be expected beforehand that this agent must exert an extremely forcible pressure upon the molecules of matter, even if every allowance be made for the extreme low density of the agent; for it is important to note that the pressure exerted is as the square of the speed of the particles of the agent, and therefore the pressure rises in a very rapid ratio as the speed increases; so that taking into account this fact, in conjunction with the high velocity of the particles, we must be prepared to find this pressure will have a very high value. In looking to physical phenomena for an indication of this pressure, and also with the object, if possible, of arriving at a limiting value for its intensity, or the value which this pressure must at least attain on the lowest computation, we will consider one observed fact. [***] 53. Secondly, it may be shown that an excess of energy is imparted to the surrounding medium by a vibrating mass or molecule, due to a second separate physical cause, which we shall now consider. We have observed that the speciality of a vibrating movement is to affect the normal velocity of the component particles of the medium in such a way that equal increments and decrements of velocity are experienced. But it is an important principle to observe, that when masses of matter experience equal increments and decrements of velocity so that the mean velocity remains unaltered, that, nevertheless, the energy being as the square of the velocity, the value for the energy does not remain unaltered. Thus, if we take the case of two equal masses having equal velocities, which we may express by V, the energy in each case being expressed by V2, and the total energy therefore by 2V2. If now we suppose one of the masses to receive an increment of velocity v, its velocity therefore becoming V + v, the other mass experiencing an equal decrement of velocity, its velocity becoming V - v; then although the mean value for velocity has remained unchanged, yet the value for energy has by no means remained unchanged, for the energy of each mass being as the square of its velocity, the total energy now becomes (V + v)2 + (V - v)2 = 2V2 + 2 v2. Now the value for the total energy before this change of velocity took place was only 2V2. The total energy has therefore, by merely changing the velocities by equal amounts (so as not to affect the mean velocity), received a notable increase represented by the amount 2v2. This is an important point, on account of the direct and practical bearing which it has on the phenomena of vibratory motion; the above indicating that the change of the velocities of the component particles of the medium by equal amounts, which it is the special function of a vibratory motion of matter to effect, is itself a direct cause whereby a certain excess or surplus of energy is communicated to the medium. [***] 98. Important Influence of Subdivision. - One of the most important practical consequences following from the extensive state of subdivision, which is the characteristic of the molecular condition of matter, is the vast extent of surface which is thereby brought under the action of the ether pressure. This is a fact of importance, by a due appreciation of which the great energy of the action of the ether upon molecules will appear no longer discordant or inconsistent, but the fact may be brought into harmony with ordinary mechanical principles, this vast extent of surface being the fitting mechanical condition for the production of static and dynamic effects of extreme intensity. [***] [114] III. High Normal Speed of Component Particles. - This physical quality is absolutely essential to constitute a powerful dynamic agent, for without this high speed dynamic effects of a high intensity cannot be produced. Second, this high normal speed of the particles is the sole condition on which the loss of motion sustained by the ether can be replenished with that degree of speed which is essential to render a continuous dynamic effect of a high intensity possible to the ether. Third, this high speed of the component particles is the sole quality by which the loss of motion sustained by the ether in producing a given dynamic effect can be subdivided or distributed over a large volume of the ether, whereby a notable local disturbance of the equilibrium of the ether is prevented. Fourth, this quality is essential for the rapid interchange of motion between masses and molecules of matter at a distance from each other, the rapidity of intercommunication or exchange of motion being strictly limited by the normal speed of the particles of the intervening agent. Fifth, this high speed of the component particles is necessary to render possible the existence of a store of energy of a high value, without the encumbrance of a large quantity of matter in space. Sixth, the high normal velocity of the ether particles is the necessary mechanical condition to enable an intense pressure to be exerted by the ether upon the molecules of matter, without the movements of these molecules and masses being obstructed by the agent exerting the pressure. For, in the first place, by this high speed of the component particles an intense pressure is attainable (more especially as the pressure rises as the square of the speed) without the necessity for the agent being dense, by which the free passage of masses of matter through the agent would be obstructed. In the second place, the high speed of the component particles enables masses of matter to pass through the agent with the least disturbance of its equilibrium, or with a minimum of resistance from this cause, the agent becoming almost impalpable; the exertion of an intense pressure by the agent being itself the necessary condition to render the agent adapted to control forcibly the molecules of matter in stable equilibrium, as exhibited in the general phenomena of 'cohesion,' or the aggregation of the molecules of matter generally. The above may serve as a general summary of the special physical qualities of the ether; and it may be noted that if the attempt were made beforehand, as a mechanical problem or speculation, to devise or scheme out what special physical qualities an agent should possess in order to be mechanically fitted to produce the varied physical effects of the character observed, then the scheme of the ether would be found to constitute the only possible solution of which the mechanical problem admits; or the ether may be contemplated as a piece of mechanism specially adapted to its work. [***] 128. We shall now proceed to consider more closely the mode or general principle upon which physical processes effect themselves, and it will be our endeavour to show that these processes resemble one another in a second fundamental aspect, viz. that all these processes are cyclical, i. e. consist in a transference of motion from the ether through matter to the ether, or consist in a transference of motion from and to the same source; and therefore that all physical processes, however diverse and varied, are identical in this fundamental respect; or that every observed motion whatever came from the ether at one time, and will return to the ether at some subsequent time. This theorem may be shown to be a necessary consequence resulting from the fundamental principle of conservation. The normal state of the ether is a state of motion, or the component particles of the ether transfer their motions among themselves, and this motion is of necessity permanently maintained. The ether, therefore, constitutes a source of motion. A mass or molecule of matter, on the other hand, cannot possibly be in motion without continually giving up some of its motion to the surrounding ether, which motion is rapidly carried off to a distance in the form of waves; so that matter cannot possibly remain in motion, unless the motion be renewed by the ether as rapidly as it is being dissipated in the ether, which would constitute a cyclical process. Since, therefore, the motion of matter is being continually dissipated in the ether, the ether constitutes the receptacle of all the motions of matter. The ether therefore must, in accordance with the principle of conservation, be the source of all the motions of matter, for matter cannot evolve motion out of itself. Also, since matter cannot retain its motion, but must be always dependent on the ether for any supply of motion, matter therefore cannot in any case constitute a source of motion. The ether therefore constitutes both the source and the receptacle of all the motions of matter, or this would constitute the theorem that all physical processes are cyclical, or consist in a transference of motion from and to the same source, and accordingly that all physical processes are correlated in this fundamental respect. [***] 135. Amount of energy being dependent on the quantity of matter in motion and on the square of the velocity of motion, and since motion cannot come into existence spontaneously, or go out of existence spontaneously, but in accordance with the principle of conservation, the sum of energy must remain constant; it follows, therefore, that whenever there is a loss of motion by matter, there must be a simultaneous gain of motion by matter, or the loss and gain of motion must be simultaneous, for a loss of motion without a simultaneous gain of motion would involve for an interval of time an annihilation of energy. It follows, therefore, as a necessary consequence from this, that the energy expended in any physical process whatever can be solely dependent on and due to motion simultaneously imparted, i. e. imparted at the time of the expenditure of the energy; for unless motion be imparted at the time, energy cannot be expended at all, for to expend motion without imparting motion would be to annihilate energy; indeed, the motion imparted is itself the measure of that expended, and is the sole cause of its expenditure, i. e. motion can only be expended in the communication of motion, and in that fact lies apparent the principle of the Indestructibility of Motion. [***] 163. Absolute Quantity of Energy in the Unit Volume of Space. - We shall now consider more particularly the energy enclosed by the ether, with the endeavour to give some idea of the absolute value of the energy represented by the motion of the ether particles contained within a given portion of space, with the object, if possible, to fix upon a limiting value for this energy, or the lowest value consistent with what physical facts would require. The conditions required in order to determine the amount of energy enclosed in the unit volume of space are clearly, first, a knowledge of the quantity of matter in the form of ether contained in the unit volume of space (i. e. the density of the ether); and secondly, the normal velocity of the ether particles. Now, although we do not know the density of the ether independently, nevertheless since density is determined by pressure and velocity of component particles, if, therefore, by a known limiting value for the velocity of the ether particles, a limiting value for the ether pressure can also be fixed upon, then a limiting value for the ether density is thereby given. The limiting value for the velocity of the ether particles is given by the measured velocity of a wave of light. As regards the value for pressure, we take the estimate already fixed upon: that this amounts to 500 tons per square inch as the lowest limiting value. There are valid grounds for inferring that this value for pressure has been under-estimated; for we assumed the total ether pressure as a small multiple of the observed difference of pressure in the case of 'cohesion,' whereas, as before remarked, it is a known fact that the force required to separate chemically combined molecules must be many times greater, this indicating the high intensity of the controlling ether pressure, and showing that an estimate of this pressure from the case of 'cohesion' must be but an inadequate representation of the reality. The tremendous energy developed in explosives, which is the very energy of the ether itself, is a direct indication of the intensity of the ether pressure, which is the necessary accompaniment of this energy. That this value for pressure has been under-estimated, a bare consideration of the dependent value for density would almost show, for the ether density corresponding to this pressure (1/5264800 of the atmospheric density) represents a density so insignificant as to be less than that of the best gaseous vacua."
Additional Notes

[12] Fechner quoted in H. Vaihinger's, Philosophy of the 'As if', Barnes & Noble, Inc., New York, (1966), p. 215; translated by C. K. Ogden.

[13] T.H. Pasley, A Theory of Natural Philosophy, on Mechanical Principles, Divested of All Immaterial Chymical Properties, Showing for the First Time the Physical Cause of Continuous Motion, Whittaker & Co., London, (1836), Preface and pp. 145-146.

[14] Pasley, ibid. xcii.

[15] See for example the many works of Marc Seguin and M. F. de Boucheporn, Cf. The Correlation and Conservation of Forces, D. Appleton, New York, (1867), pp. 4, 76-82; W. B. Taylor, "Kinetic Theories of Gravitation", Annual Report of the Board of Regents of the Smithsonian Institution, U. S. Government Printing Office, Washington, (1877), pp. 205-282. Another good example is A. Anderssohn, Die Mechanik der Gravitation, Breslau, (1874); and Zur Loesung des Problems ueber Sitz und Wesen der Anziehung, Breslau, (1874); and Physikalische Prinzipien der Naturlehre, G. Schwetschke, Halle, (1894). See also: G. Hoffmann, Die Anderssohn'sche Drucktheorie und ihre Bedeutung für die einheitliche Erklärung der physischen Erscheinung, G. Schwetschke, Halle, (1892). For some, the aether become their embodiment of the Tertullian-Newtonian pantheistic God and Holy Wind. See, for instance, Philipp Spiller, Die Urkraft des Weltalls nach ihrem Wesen und Wirken auf allen Naturgebieten, Verlag der Stuhr'schen Buchhandlung (S. Gerstmann), Berlin, (1876).

[16] G. G. Coriolis, Du calcul de l'effet des machines, ou Considérations sur l'emploi des moteurs, Paris, (1829). Coriolis used the term "force vive". First use of the term "kinetic energy" in English is perhaps by Thomson and Tait, Good Words, (October, 1862).

[17] T. Young, A Course of Lectures on Natural Philosophy and the Mechanical Arts, Volume 1,Taylor and Walton, London, (1845), p. 59.

[18] J. R. Mayer, translated by J. C. Foster, "Remarks on the Mechanical Equivalent of Heat", The Correlation and Conservation of Forces, D. Appleton, New York, (1867), pp. 331, 336.

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Christopher Jon Bjerknes is an American historian of science, who has authored six books and numerous articles on the theory of relativity and on Albert Einstein. His most recent book, Albert Einstein - The Incorrigible Plagiarist, is reviewed in this same volume of Episteme.