Review of Ennis' Origin of the Stars [From North American Review 104.2 (April 1867): 618-626.] ³³

4. — The Origin of the Stars, and the Causes of their Motions and their Light. By Jacob Ennis. New York: D. Appleton &Co. 1867. 12mo. pp. 385.

This book is full of errors of fact and fallacies of reasoning, and yet will probably not be challenged by one in ten of its readers for either of these defects. The author appears sufficiently well informed and sufficiently well disciplined in the matters he discusses to avoid the criticisms of common-sense and ordinary information on scientific subjects. But this is all. The questions he discusses require for a competent handling an expert’s discipline and knowledge, in both of which the author shows deficiencies which would be surprising were they not so common in writers and lecturers on such subjects.

The implicit confidence with which statements of scientific facts and arguments are received by the readers of popular scientific books and by popular audiences now-a-days, is like that which was once accorded to the assumptions and argumentations of theological writers and speakers. Such trust was then, as it is now, creditable to those who entertained it, inasmuch as the statements and arguments were opposed by nothing in the listener’s own experience, and no motive was apparent which could induce his instructor to mislead him, or to state with confidence facts which are not really known, or to offer arguments which are not really valid. On the contrary, the seeming motive both in theology and science is a genuine love of truth, uncorrupted by selfish ends. But how often is the real motive an egotistical love of opinion instead of truth, and a narrow advocacy of prejudices!

With, a pleasing naïveté our author confesses himself a believer in the “nebular hypothesis.” He entertains no doubts on the subject, and is confident that no doubt will remain in the minds of his readers, especially on those features of the theory which are original with himself. But a clear, open, enthusiastic advocacy of a scientific position, especially of one which is generally discredited, affords to the more cautious students of science a prima facie presumption against an inquirer’s competency. Advocacy is a method adapted peculiarly to practical questions, in the discussion of which truth is not the only, or even the main object; since some decision, authoritative at least, if not true, is often demanded for the occasions of future conduct in practical matters. Not so in science. Its questions can afford to wait and forego the dubious advantage of one-sided discussions, since no practical issues follow from the facts of science until they are ascertained beyond dispute. An enthusiastic defence of a belief, though often admirable in practical matters, since it is often a defence of truth against authority in practice, has no place in positive science, and dwindles to the proportions of a narrow, often obstinate, advocacy of mere opinion.

Accordingly, the better sort of writers on the “nebular hypothesis ” love rather to discuss it for what it is really worth as a means of concatenating and co-ordinating certain facts of science, which otherwise in the present state of our knowledge would remain outstanding problems. So unsatisfactorily, however, has this function been fulfilled by the nebular hypothesis, that the best later writers regard it as an hypothesis of which the best that can be said is, that it is not likely soon to be supplanted by any other. Our author quotes a long list of writers who have acknowledged one of the most serious defects of this hypothesis, namely, that the mutual gravitation of the parts of the supposed original nebulae could not have caused the motions of rotation and revolution which exist in our solar system and in some of the compound stars, and that these motions or their equivalents in rotation must have existed in the supposed original nebulous masses. It is upon the characters and relations of these motions in the solar system, and among the members of sidereal systems, that the main argument for the nebular hypothesis is based; namely, that the characters and relations of these motions imply a common origin. To get beyond this first step, the hypothesis has been obliged to assume, not only that all the matter of the solar system, but also the resultant of its motions of revolution about its common centre of gravity, existed in the supposed diffused mass of the nebula;

since it is one of the fundamental principles of mathematical mechanics, — the principle of the “conservation of areas,” — that no “rotation area” can be added to or subtracted from the amount existing in any independent body or system of bodies through the mutual actions of its parts, whether these actions arise from gravitation, collision, or friction. This principle is an immediate deduction from the primary laws of motion, and especially from the third, the law of the equality of action and reaction in all mechanical phenomena.

It would, therefore, naturally be supposed that our author quotes this list of authorities in proof of the position that the total “rotation area” of the solar system existed entire in the supposed original nebula. But this is not at all his object, which appears rather to be self-glorification, — to show what an array of scientific genius he has triumphed over, by solving the problem which has baffled them all! He has proved to his entire satisfaction that the mutual gravitation of the parts of an irregularly shaped but originally quiescent nebula will result in its rotation, and his argument deserves a place among the curious paradoxes with which inventors of perpetual motion, anti-Newtonian heretics, and squarers of the circle have enriched the literature of science. Though not so palpably absurd, it is still of the same character as the efforts of the man who should essay to lift himself by the straps of his boots.

That the weight of a gravitating body can be converted into a motion around the centre of gravity of the system to which it belongs, is clear to the author from certain familiar examples on the earth. Sliding down an inclined plane, the motion forward and around the earth’s centre which a train of cars, for example, acquires by its own weight on a downward grade of a railway, or the forward motion of a bird descending on the air, — are not these cases of the conversion of falling forces into motion around the centre of gravity? Such is the author’s argument. That he should have overlooked the fact, patent in the most elementary analysis of so simple a problem as the inclined plane, that one component of gravity in the sliding body urges the inclined plane, or the masses on which it rests, by the same amount backward, as the other component urges the body forward, is truly surprising in a teacher of the natural sciences.

By no such movement can a surplus of motion be produced in any direction about the centre of gravity of a system, or indeed about any other fixed point in space. This follows almost immediately from the law that action and reaction are equal in all kinds of mechanical phenomena, — in attractions, repulsions, collisions, and frictions. The “conservation of areas” and the “conservation of the centre of gravity” are twin doctrines of mechanical philosophy, equally fundamental,

precise, and extensive in their applications, and are among the most certain of the laws of nature. Equally proper would it have been for the author to argue that an irregular shape in the original nebula could have transferred it en masse to a new position, or caused a motion in its centre of gravity, as to argue that such a shape could have set it spinning on its axis.

We are aware that a majority of readers are as much “in the fog” as he on the subjects of our author’s speculation, and this is our apology for taking so much space in noticing a book which otherwise would scarcely deserve a notice. We desire to warn the reader against fallacies which would greatly intensify the fog. Let us suppose, then, since mechanical principles experienced in the actions of our own muscles are best brought home to our common sense, — let us suppose that a living human body could be placed at rest in the midst of the stars, removed from any sensible influence from other bodies. Let the muscles play as they may, let the man writhe and plunge, contract and expand his limbs as much as he can, he will find, on assuming any fixed posture, that he has not changed his position one iota, nor acquired any continuous motion; and on relaxing his muscles, he will find that he still faces in the same direction, and that his head and feet still point to the same invariable poles. Action and reaction have always and everywhere been equal. No more can a nebulous mass acquire a motion of translation or rotation by the mutual actions of its parts. The motions produced by the falling in of its parts on the contraction of the nebula must always balance each other by current and counter-current, or be converted by friction and collision into heat, which is only another form of balanced motions, the minute molecular vibrations of bodies. But the “areas of rotation” must in the aggregate forever remain unchanged.

If we could suppose two living bodies, instead of one, placed as we have supposed, but within reach of each other, these two could turn each other round in opposite directions, and push each other apart or draw each other nearer to their common centre of gravity, but no unbalanced rotation around this centre and no motion of this centre could be produced by their mutual action. In the same way, if two nebulæ, instead of parting company, as is commonly supposed, should continue to act on each other, they might by supposable forces or supposable conditions of gravitative action set each other into opposite rotations, like opposite vortices in water; or one nebulous mass might acquire opposite and balancing vortical movements in its internal and external parts. We throw out this hint for the benefit of our author and others who may be disposed to pursue the subject further.

Having staked his reputation on the mechanical thesis which we have examined, our author omits to consider, if indeed he is aware of, the several other mechanical difficulties which recent and more careful investigations of its mechanical conditions have found to beset the nebular hypothesis; such as the facts that the nebulous rings of this hypothesis could not have equal angular velocities or rates of revolution on their external and internal parts, and that, if broken at all, they would most likely be broken into many parts; and the fact that the planets or planetoids so formed would revolve on their axes in directions opposite the actual rotations of the real planets.

The author sacrifices the only real triumph, the most satisfactory result, of the nebular hypothesis, to another of his pet theories, in which at the present day he almost stands alone, namely, the theory that the origin of the heat and light of the sun and the stars is “chemical action.” The “establishment” of this theory occupies the first part of his volume. The one triumph of the nebular hypothesis is the explanation it has afforded, in the hands of modern physicists, of the constant and almost unlimited production of light and heat by the sun, which the geological periods would appear to demand. If the sun can be regarded as at present in a state analogous to its supposed parent, the nebula, and to be still contracting, the falling force thus brought into action — which cannot, as our author erroneously supposes, be converted into rotation, but which must be exhibited by counter-currents or balanced motions about the centre, and finally be converted into heat — this falling force would be sufficient to supply all the energy expended by the sun’s radiations if the contraction of the sun’s diameter should only amount to one part in twenty millions in a year, a rate so slow as to be insensible in its effects on the sun’s apparent diameter from the earliest observations to the present day. This conclusion is not a matter of conjecture or opinion, but matter of demonstration. All that is hypothetical about it is the supposed present contraction of the sun at the given rate. The rest follows according to the best ascertained and most universal of the laws of nature. But while holding to the hypothetical nebulous part of the proposition, as matter of certainty, our author ignores or is ignorant of its unavoidable conclusion; and holds to the “chemical theory” of the origin of cosmical light and heat, as the only adequate one, the only objections to which are “unfounded assumptions.” He is confident of his readers’ assent to this position, when they have duly weighed his arguments. Throughout he argues as if the subject were not, as it really is, involved in the densest obscurity. All that appears to him requisite for the establishment of the “chemical theory” is the removal of the objection which he discovers

to rest on “ three unfounded assumptions.” This objection is, that the chemical theory is inadequate, — that there is not fuel enough in the sun to support combustion for so long a period as the sun is known to have shone. This appears, first, from the known amounts of heat given out in combustion by known chemical elements and compounds; secondly, from the known conditions which modify these amounts; and thirdly, from the known limits of the matter of the sun which can be supposed to be combustible. The author sums up his answer as follows: —

“I have shown that this objection — the want of fuel in the sun — is unfounded; for it proceeds on the three unwarrantable assumptions. In opposition to the first assumption I have shown that it is possible, and even probable, that the materials of the sun, pound for pound, give out far more heat than those of the earth. In opposition to the second assumption I have shown that it is possible, and even probable, that, in the vastly different conditions of chemical action in the great central orb of our system, more heat may be given out by the very same materials than in our small furnaces. In opposition to the third assumption I have shown that it is possible, and even probable, that by the action of the physical forces at work in the process of chemical action and condensation, new fuel may be constantly prepared to keep alive the burning of the sun.” — p. 205.

In other words, to the positions which are assumed in accordance with all that is certainly known of combustion, the author replies by assuming a great deal of which we know and can know nothing with certainty; and he calls this demonstration!

If we reason at all from science about the origin of things or about phenomena beyond the reach of scientific tests, we should confine ourselves to what we know most pertinent to the matter. If we may call in ad libitum what is “possible,” or “even probable,” on vague analogies, because we have not yet arrived, or cannot arrive, at any certainty, then we may as well free ourselves altogether from the limitations of science, and build as widely and freely as fancy may choose.

The author appears throughout his argument to regard the “objection” he combats as one supposed to disprove, instead of one which merely discredits, his theory. There is no question of absolute proof or disproof involved in the matter, and the real objection to his theory is untouched by his discussion. It is this. Chemical forces as we know them are not only inadequate, but vastly more inadequate for the production of cosmical light and heat than two other known sources of heat, under the conditions presented by the sun and similar cosmical masses. One of these sources would exist in the contraction of the sun’s mass supposed by the nebular hypothesis, through the enormous falling force which would thus be brought into action; and the other

would have effect in the supposed fall to the sun of meteoric masses. Both of these, when tested mathematically in accordance with known laws of nature, are found to exceed vastly the known resources of combustion, even if we modify these as much as we can, in accordance with conditions known to affect them. Indeed, there is no real alternative between the chemical and the mechanical theories of cosmical light and heat. There is only a question of priority; and this should be decided, if decided at all, by what we know, and not by what we may be ignorant of.

We have no space to illustrate adequately the author’s numerous and curious misstatements and errors in science; but one instance pertinent to the case in hand may suffice. He says: —

“The idea that by chemical action a pound of matter of any kind all over the universe, and under all possible physical conditions, must give only the same amount of heat as a pound of our charcoal burned in the open air, has been a very pleasing idea; but it it is rashly theoretical,” &c. — p. 180.

This idea is not only rashly theoretical, but in direct contradiction to well-known and long-known determinations in chemical physics. Certainly no chemist could be pleased with it, and all that any one would venture to maintain at all resembling it is, that given quantities of given kinds of matter, of given densities and forms of aggregation, will under all known variations of other conditions produce in combustion determinate quantities of heat. And these are of such an order of magnitude as to discredit our author’s theory, if speculation on such subjects be limited, as it should be, to reasonings from what we know, and in analogy with what we know.

But our author’s positive grounds for his “chemical theory” are in reality theological. He says: —

“If there be any truth more plain than all others, it is that God, in creating, upholding, and governing the world, works by agencies and according to law, and that his process is invariably from the simple to the complex. [!] .... The chain of dependencies from the body of a man back through plants and compound minerals to the simple elements is a large one, interlinking many agencies and laws; and it is most irrational to say that in the original creation God began somewhere in the middle of this chain, — say with compound minerals. No! He began with the beginning; this is ‘ the way of the Lord.’ He began with the simple elements, and combined them according to his ordained and combining laws!”— p. 62.

Again: —

“The simple elements were formed separately, and afterwards combined; because God has created a special agency called ‘Chemical Force,’ acting according to a complicated system of laws, whose object is to unite or combine these elements.” — p. 63.

A few pages further on he says: —

“The simple elements were originally created separate, and afterwards combined by laws, because their creation in a compound state would have involved an infinite number of miracles, without any object for such miracles. .... To form a compound mineral otherwise than by the laws above given would be a miracle without any assignable object. It would be a miracle in mere idleness, the very thought of which is an impiety.” — p. 65.

To our mind there is a much greater impiety in the confident manner in which the author thus pretends to a knowledge of God’s ways and designs, and imputes his theory to the Almighty. We would not accuse him of a conscious impiety. Indeed, we are convinced that he is not the less pious, because his love of his theory is so much greater than his caution or his regard for the simple truths of fact. But one would naturally infer from his statements that he regards the great “reducing” processes of nature, and the processes by which chemists have discovered the “ultimate elements,” as magical and diabolical ones, and analytical chemistry as still one of the “black arts.” It would seem also, that heat, which decomposes many chemical compounds, and is probably able to decompose them all, works contrary to “the way of the Lord.”

But in sober truth “the way of the Lord,” so far as it can be known by the laws of physical science, is always and everywhere equally by process and counter-process. No chemical compound, known to be such, can exist, which is not decomposable by processes as natural and as much the ways of the Lord as those which our author regards as peculiarly divine. Moreover, the laws of mechanical and chemical physics point to no such simple beginning, and to no such progressive development of the universe as a whole, as are assumed, without warrant from science, in the nebular hypothesis. In one respect this hypothesis is legitimate and worthy of serious attention. In so far as it attempts to account, however inadequately in our present state of knowledge, for effects which are obviously of a physical origin, its claims to respect are clear. But as ordinarily presented and discussed, this hypothesis involves a problem and an assumption which are entirely foreign to science. Physical science knows no beginning, and from its own principles it has no right to presume one; and it is quite out of its element when employed to simplify the universe “at the beginning,” — to lessen the labor of Omnipotence! — to reduce to its lowest terms the miracle of creation! But this use of natural laws is an unconscious testimony to the aversion to miracles which scientific conceptions have engendered. In the merely physical explanations which the nebular hypothesis suggests, cosmologists like our author and Mr. Herbert

Spencer have little or no interest. They welcome it rather on account of its fancied solutions of problems quite foreign to science.

One other remarkable feature of our author’s method deserves notice, a feature not unprecedented in efforts of the same sort, namely, the putting of a scientific question to a vote of “facts,” on the principle, apparently, of free and impartial suffrage and numerical majorities. The “facts” which various theories “account for” are duly marshalled, paragraphed, and numbered by the author. Forty-seven facts prove the resemblance of the earth to the planets; twenty-three, that the fixed stars are suns; twenty-eight, the author’s theory that the earth was once self-luminous like the sun. “Eight facts or classes of facts” prove his theory that the chemical elements were “formed during the period of nebular condensation.” The chemical theory “accounts for” seventy-one facts, and gravity “accounts for” fifty-three free and independent facts in the solar system.

It must be confessed that the magnitude of these numbers is in many cases due to a want of entire independence among the “facts,” and oftener to the circumstance that many of them are only interpretations of fact in accordance with theory. Some of the facts, moreover, need qualification, others confirmation, and nearly all lack that power of demonstration which the author attributes to them. Their strength lies in their numbers, but the genuine truths of science do not depend on such crude numerical inductions. One fact as well ascertained as the law of gravity might be sufficient to rout the whole seventy which the author’s chemical theory “accounts for,” without injury to the substantial merits of a single one; though it would hardly be able to do so if it depended on evidence no more cogent than the fifty-three which gravity accounts for, according to the author. In reality, gravity accounts with mathematical precision for as many thousands of facts, — facts of particular and direct observation. And this is the only kind of evidence which ought to be considered as a basis of physical demonstration.