PART III.

_EVIDENCE IN SUPPORT OF THE THEORY FROM THE PRE-NEBULAR CONDITION OF THE

UNIVERSE._

The nebular hypothesis, strictly speaking, is one simply intended to

account for the origin of our solar system. “It is,” as remarks

Professor A. Winchell, “primarily a genetic explanation of the phenomena

of the solar system; and accessorily a co-ordination, in a common

conception, of the principal phenomena in the stellar and nebular

firmament, as far as human vision has been able to penetrate.”[62] The

theory starts with the assumption that all the materials composing the

solar system once existed in a state of extreme tenuity and diffusion,

filling far more than the entire space included within the orbit of the

most remote planet. It begins with this diffused nebulous mass tending

slowly, under the influence of gravitation, towards a state of

aggregation. Beyond this point the received nebular hypothesis does not

extend.

[Footnote 62: _World Life_, p. 196.]

It will be observed that the theory here begins in the middle of a

process. It begins with the assumption of a mass in the act of

condensing under the influence of gravity. It offers no explanation of

the origin of the mass, or how it came to be in this attenuated state,

or in what condition it existed before the materials began to draw

together. These are, however, inquiries which naturally force themselves

on our attention. If the nebular theory be a true theory of the origin

of the solar system, then this nebulous mass must have had an antecedent

history, and we cannot help feeling the instinctive desire of tracing

the chain of causation farther back. The mind presses towards an

absolute beginning. It is the goal to which it aspires, and no amount of

failure will ever deter it from renewing its efforts. Of recent years a

considerable amount of attention has been devoted to inquiries in this

direction; nearly all of which, it is true, has necessarily been of a

speculative and hypothetical character. But hypothesis, as Mr. Locyker

remarks, is the life-blood of investigation.

The nebular hypothesis is so highly probable as to have gained almost

universal acceptance. In fact, it contains very little of a hypothetical

nature. It is, as Mr. Mill says, “an example of legitimate reasoning

from a present effect to its past cause, according to the known laws of

that cause.” Like the hypothesis of a luminiferous ether, if it is not a

true theory, one would almost think that it deserves to be so.

There seems no reason why inquiries should stop at the point where

Laplace began. The same line of reasoning may yet carry us back into the

pre-nebular region, and perhaps with as great a degree of certainty as

it has done in the nebular; though, no doubt, the farther back we

proceed, the more difficult probably will the inquiry become. But, be

all this as it may, there can be little doubt that the path of

investigation is a legitimate one, and also one which is worthy of being

traced out.

I shall now briefly refer to some of the leading views which have been

expressed in regard to the pre-nebular history of the universe, and

shall afterwards consider the additional light which the theory

discussed in this volume seems to cast on the subject.

The commonly received opinion is that the nebulæ were formed from

ordinary matter existing in a high state of division, and widely

diffused through space. The “cosmical dust,” as it is called, was the

universal “world-stuff,” out of which all things were supposed to be

formed. It is held that in receding backwards in pre-nebular times, the

smaller, more simple, and elementary the materials were. Out of this

primitive cosmical dust, or world-stuff, by aggregation, the materials

became successively larger and more complex. The theory of the origin of

nebulæ, on this principle, has been clearly stated by Professor

Winchell, and I here give a brief outline of his views on the subject.

_Professor A. Winchell on the pre-nebular condition of matter._—This

cosmical dust, or world-stuff, he considers to be scattered

promiscuously through boundless space. It is cold and non-luminous, and

is acted upon by forces of attraction and probably of repulsion. The

material particles, either as atoms or less probably as molecules, are

drawn by mutual attraction into groups and swarms. Any central

attractive force, as of a sun or planet, by causing the particles to

move in converging lines, would cause them to become approximated and

ultimately aggregated. Thus both mutual attractions and centric

movements would tend to produce aggregations dispersed through space.

But in the presence of two or more attractive centres, as in the present

constitution of the Cosmos, it is impossible that any mass shall fall

directly upon its centre of attraction. Hence motions of rotation will

be established in the mass, and also orbital motions of masses about

each other. In addition to the mutual attraction of the molecules, the

convergence of their paths towards centres of attraction must also tend

to the formation of masses and swarms of masses and particles. “We have

then,” he says, “to picture indefinite space as pervaded by swarms of

masses and particles of dark matter. Each mass or particle may,

nevertheless, be separated by thousands of miles. It is manifest,

therefore, that each mass or particle will eventually dispose itself,

under the fixed action of the forces of matter, in some definite order.

It is manifest also, from what has been said, that each swarm will have

a progressive motion along a path having the essential character of an

orbit around some dominant centre of attraction. If, as seems to be the

fact, an ethereal medium, or any condition of interplanetary matter,

exists in space, it opposes the movements of these swarms by opposing

the motion of each constituent mass. But the smaller masses—the

particles and molecules—would feel this resistance to the greatest

extent. They would therefore fall behind the heavier masses, and would

be most deflected toward the attracting centre. The smallest particles

would be driven farthest to the rear, and dispersed farthest from the

orbit of the train, along the side turned toward the principal

attraction. The swarm would present an elongated form, in which the

larger and heavier masses would move foremost, and nearest the line of

the orbit—that is, near the exterior skirt of the area covered by the

general swarm—while the smaller ones would follow, in graduated

succession, in a long train which would present a fan-like expansion

lying mostly on the inside of the path of the principal masses.”

“This, it may be conceived, is the mode of aggregation of these cosmical

matters in the depths of space. Of course the attractions which control

them are feeble; their movements are slow, the resistances are

relatively inconsiderable, and the elongation of the swarm is

correspondingly inconspicuous. What I have described is a tendency which

would be present. Sometimes the controlling attraction would be only

another cosmical swarm. The two swarms would revolve similarly about

their common centre of gravity, while prolonged resistances would cause

their slow approximation and final coalescence at the common centre of

gravity. Sometimes the controlling attraction would be exerted by a

distant sun, around which it would slowly move, continually gathering up

additions of matter from the wide fields of space.”

“In most cases all controlling attraction would be feebly felt. These

clouds of cosmical dust would float practically poised in the midst of

space, and would gradually grow by the continued accession of new

matter. Some of them would become aggregates of large dimensions, and

their attraction would be distinctly felt by other aggregates. There

would be a tendency of such aggregates to approach each other. They

might possibly approach along a straight line; but more probably some

third aggregation, or some distant sun, would deflect them into orbits

about their common centre of gravity, in which, by prolonged collisions

of cosmical matter, they are brought to ultimate coalescence with each

other. Or some other attractive disturbance affords such a resultant of

actions as may bring them more directly together. When these larger

aggregations of world-stuff come together, the result is an aggregation

approaching the dimensions of the Herschellian nebulæ.”[63]

[Footnote 63: _World Life_, p. 72.]

In regard to the origin of the heat of the nebulæ, I am glad to find

that Professor Winchell, to a certain extent, adopts the views which I

have so long entertained on the subject. “The thought,” he says, “must

already have suggested itself to the reader that the process of

conglomeration affords an explanation of the intense heat which

vaporises its substance, and causes it to yield a spectrum of bright

lines. As the sudden compression of a portion of atmospheric air yields

heat sufficient to ignite tinder, or fuse and volatilise a descending

meteor-mass, so the precipitation of one planet upon another would

liberate sufficient heat to reduce them both to a state of fusion, or

even of vapour. Still more must the intensest heat be generated by the

impact of two nebulous masses, one or both of which together may embrace

more matter than all our planets and the sun combined—as much even as

the matter of our entire visible firmament of stars. One experiences a

distinct feeling of relief in the discovery of such a possible means of

ignition of nebulæ.”

_Mr. Charles Morris on the pre-nebular condition of matter._—Others

again suppose matter to be present everywhere throughout space. This

view has been ingeniously advocated by Mr. Charles Morris in an article

on “The Matter of Space,” which appeared in _Nature_, February 8, 1883.

The hypothesis of an ether specially distinct from matter he considers

to be a gratuitous assumption, and one of the last surviving relics of

eighteenth century science, and, unless it can be proved that highly

disintegrated matter is positively incapable of conveying light

vibrations, there is no warrant for assigning this duty to a distinct

form of substance. But that matter exists in outer space in the same

conditions as in planetary atmospheres he thinks is improbable. Its duty

as a conveyer of radiant vibrations seems to require a far greater

tensity, and its disintegration is probably extreme. Assuming matter

throughout the universe—here as condensed spheres, and there in outer

space as highly rarified substance—the atmospheric envelopes of the

spheres, he considers, will gradually shade off into the excessively

rare matter of mid-space. Matter may exist in countless conditions as to

simplicity and complexity, &c., but the base particle he assumes to be

the same under all conditions. In the spheres there is matter ranging

from the simplest elementary gases, through the mineral compounds of the

solid surface, to the highly compounded organic molecules. In outer

space the variation is in the opposite direction; the matter existing

there in a highly disintegrated condition.

Every particle he considers to possess a certain amount of motor energy

in the form of heat. As the total amount of this energy in the universe

remains unchanged, a particle can only lose energy by transferring it to

others. This heat energy acts, of course, in opposition to gravity: it

tends to repel the particles from each other, while gravity, on the

other hand, tends to draw them together. The former acts as a

centrifugal, the latter as a centripetal energy. If the heat momentum of

the particles be insufficient to constitute a centrifugal energy equal

to the centripetal energy of gravitation, then the material contents of

space will be drawn into the attracting spheres as atmospheric

substance, and outer space, in this case, will be left destitute of

matter. If, on the contrary, the centrifugal energy of the particles be

sufficient to resist gravitation, then the particles will remain free,

and space will continue to be occupied with matter. As has been stated,

the sum of motor energy in the universe remaining unchanged, the

aggregation of atmospheric substance around any planet resulting from

the loss of motor energy must cause an increase of motor energy in the

particles outside.

The theory seems to dispense with the necessity for assuming a

luminiferous ether, for the functions attributed to the ether may, it is

thought, be performed by the particles themselves; a view which has been

advocated by Euler, Grove, and others. The origin of nebulæ, according

to the theory, is accounted for as follows:

“The nebular hypothesis,” says Mr. Morris, “holds that the matter now

concentrated into suns and planets was once more widely disseminated, so

that the substance of each sphere occupied a very considerable extent of

space. It even declares that the matter of the solar system was a

nebulous cloud, extending far beyond the present limits of that system.

From this original condition the existing condition of the spheres has

arisen through a continued concentration of matter. But this

concentration was constantly opposed by the heat energy of the

particles, or, in other words, by their centrifugal momentum. This

momentum could only be got rid of by a redistribution of motor energy.

If, for illustration, the average momentum of the particles of the

nebulæ was just equivalent to their gravitative energy, then a portion

of this energy must radiate or be conducted outwards ere the internal

particles could be held prisoners by gravitation. The loss of momentum

inwardly must be correlated with an increase of momentum outwardly.

“This is a necessary consequence of the heat relations of matter. As

substance condenses, its capacity for heat decreases and its temperature

rises, hence a difference of temperature must constantly have arisen

between the denser and the rarer portions of the nebulous mass, and

equality of temperature could be restored only by heat radiation. This

radiation still continues, and must continue until condensation ceases

and the temperatures of the spheres and space become equalised; but this

is equivalent to declaring that as the particles of the spheres decrease

in heat momentum those of interspheral space increase, and if originally

the centrifugal and centripetal energies of matter approached equality

they must become unequal, centripetal energy becoming in excess in

spheral matter, centrifugal energy in the matter of space. Thus, as a

portion of the widely distributed nebulous matter lost its heat, and

became permanently fixed in place by gravitative attraction, another

portion gained heat, became still more independent of gravity, and

assumed a state of greater nebulous diffusion than originally. The

condensing spheres only denuded space of a portion of the matter which

it formerly held, and left the remainder more thinly distributed than

before. The spheres, in their concentration, have emitted, and are

emitting, a vast energy of motion. This motor energy yet exists in space

as a motion of the particles of matter, which, therefore, press upon

each other, or seek to extend their limits, with increasing vigour, so

that the elasticity of interspheral matter is constantly increasing.”

_Sir William R. Grove on the pre-nebular condition of matter._—Amongst

the first to advocate the view that ordinary matter is everywhere

present in space was Sir William R. Grove. In a lecture delivered at the

London Institution as far back as January 1842, he stated that it

appeared to him that heat and light, according to the undulatory theory,

were the result of the vibrations of ordinary matter itself, and not

that of a distinct ethereal fluid. Twenty years afterwards, referring to

the views he then advanced, he says: “Although this theory has been

considered defective by a philosopher of high repute, I cannot see the

force of the arguments by which it has been assailed; and, therefore,

for the present, though with diffidence, I still adhere to it.”[64]

[Footnote 64: _Correlation of Physical Forces_, p. 164 (fifth edition),

1867.]

He adduces a great many facts and forcible arguments in support of his

position. He says that “there appears no reason why the atmosphere of

the different planets should not be, with reference to each other, in a

state of equilibrium. Ether, or the highly attenuated matter existing in

the interplanetary space, being an expansion of some or all of these

atmospheres, or of the more volatile portions of them, would thus

furnish matter for the transmission of the modes of motion which we call

light, heat, &c.” It is assumed in the theory, of course, that matter

must form a universal planum.

Sir William Grove favours the idea that the universe is illimitable in

extent, a view held by many eminent thinkers.

EVOLUTION OF THE CHEMICAL ELEMENTS, AND ITS RELATIONS TO STELLAR

EVOLUTION.

We come now to the consideration of a subject which has a most important

bearing on the question of stellar evolution, viz. the genesis and

dissociation of the chemical elements. The evolution of one element from

another is, it is true, as yet but a mere hypothesis, but it is an

hypothesis well supported by a host of facts and considerations, and

held by a large number of our leading chemists and physicists. “The

demonstrated unity of force,” says Professor F. W. Clarke,[65] “leads us

by analogy to expect a similar unity of matter; and the many strange and

hitherto unexplained relations between the different elements tend to

encourage our expectations.” The hypothesis throws much light on some

obscure points in stellar evolution. In regard to this, Professor Clarke

justly remarks that “it is plain that the nebular hypothesis would be

doubled in importance, and our views of the universe greatly expanded,

if it could be shown that an evolution of complex from simple forms of

matter accompanied the development of planets from the nebulæ. Evolution

could look for no grander triumph.” In fact, it is difficult to

understand how our sun and the stars could have been evolved from nebulæ

without assuming an evolution of the chemical elements. The true nebulæ

show the presence of only two elements, nitrogen and hydrogen, but our

sun contains more than a dozen of distinct elements, and the planets

more than three times that number. How, then, could all these have

arisen out of nebulæ composed simply of nitrogen and hydrogen? The

matter is plain if we assume an evolution of the elements.

[Footnote 65: _Popular Science Monthly_ for January 1873.]

The stars have been classed into four groups, which, as Professor Clarke

has remarked, indicate different stages in the process of evolution. The

first class, containing white stars like Sirius, show the predominance

of hydrogen and a scarcity of the metallic elements. In the second class

the metallic elements become more numerous and the hydrogen less

distinct; while in the third class hydrogen is difficult to detect.[66]

This seems to show a gradual development of the chemical elements as the

star cools and grows older. I shall now give a brief account of the

views expressed on the subject by some of our leading physicists and

chemists.

[Footnote 66: See also on this point Mr. Lockyer’s “Bakerian Lecture,”

_Proc. Roy. Soc._ No. 266, p. 21.]

It will be observed, in reference to the theories we have just

considered, that the process of evolution is supposed to take place from

the smaller to the larger aggregates of matter. Beginning with an

extreme condition of tenuity, by aggregation, the materials become

successively larger and more complex. In passing backwards in the

process we find the aggregates becoming less and less till they reach

the “cosmical dust,” or “fire-mist,” out of which the primitive nebulæ

were supposed to be formed. Receding still farther back, we have the

universal atmosphere from which the fire-mist is assumed to have been

derived.

This universal atmosphere, though in a state of extreme tenuity, is, as

we shall see, supposed by some to be in a more elemental form than

anything revealed to us in the laboratory. The suggestion of the

dissociation of the chemical elements and its application to stellar

physics was, I think, first advanced by Sir Benjamin Brodie in 1866, and

more fully in 1867. In the latter year views similar were considered

more fully by Dr. T. Sterry Hunt. The question of the dissociation of

elements has been ably discussed by Mr. Lockyer in his various writings.

It has been suggested by Mr. Lockyer that the coincidence of rays

emitted by different chemical elements when subjected to very high

temperatures affords evidence of a common element in the composition of

the metals producing the coincident rays. Mr. Lockyer states that many

trains of thought suggested by solar and stellar physics point to the

hypothesis that the _elements themselves, or at all events some of them,

are compound bodies_.[67] This view was also put forward by Professor

Graham, who says “that it is conceivable that the various kinds of

matter now recognised in different elementary substances may possess one

and the same element or atomic molecule existing in different conditions

of mobility. The essential unity of matter,” he adds, “is an hypothesis

in harmony with the equal action of gravity upon all bodies.” Similar

views have been advocated by M. Dumas, who based the suggestion of the

composite nature of the elementary atoms on certain relations of atomic

weights. The composite nature of the chemical elements has also been

maintained by Henri Sainte-Claire Deville, and also by Berthelot, who

held that the atoms of the elements are the same, and distinguished only

by their modes of motion. Professor Schuster, in a paper read before the

British Association in 1880, supports the view of the dissociation of

the chemical elements.

[Footnote 67: _Proc. Roy. Soc._ vol. xxviii. p. 160.]

That all the purely physical sciences will one day be brought under a

few general laws and principles, and the whole of the recognised

chemical elements will be resolved into one or two material elements, is

a conclusion towards which physical science seems at present slowly

tending. There is certainly something fascinating in this view of the

unity of nature. There is in this idea more than a purely physical

interest attached to it. It has, as I hope to show in a future work, an

important bearing on questions relating to the foundations of the true

theory of evolution.

The question of the unity of the chemical elements is one, however, yet

in a hypothetical condition. Professors Liveing and Dewar, who have

given attention to this subject, say: “The supposition that the

different elements may be resolved into simpler constituents, or into a

single one, has long been a favourite speculation with chemists; but,

however probable this hypothesis may appear _à priori_, it must be

acknowledged that the facts derived from the most powerful method of

analytical investigation yet devised give it scant support.”[68]

[Footnote 68: _Proc. Roy. Soc._ vol. xxxii. p. 230.]

_Sir Benjamin Brodie on the pre-nebular condition of matter._—There are,

considers Sir Benjamin Brodie, very forcible reasons which lead us to

suspect that chemical substances are really composed of a primitive

system of elemental bodies, analogous in their general nature to our

present elements: that some of those bodies which we speak of as

elements may be compounds. These ideal elements assumed by him, he says,

“though now revealed to us by the numerical properties of chemical

equations only as _implicit and dependent existences_, we cannot but

surmise may sometimes become, or may in the past have been, _isolated

and independent existences_”—as, for instance, in the case of the sun,

where the temperature is excessive. “We may,” he further adds, “consider

that in remote ages the temperature of matter was much higher than it is

now, and that these other things [ideal elements] existed then in the

state of perfect gases—separate existences—uncombined.”[69] He then

refers to certain observations of Mr. Huggins and Dr. Miller on the

spectra of nebulæ where one of the lines of nitrogen was found alone;

and that this suggested to them that the line might have been produced

by one of the elements of nitrogen; and that nitrogen may therefore be

compound. He mentions as a significant fact that a large proportion of

the class of elements which he has termed “composite elements” has not

been found in the sun, they having probably been decomposed by the

intense heat.

[Footnote 69: _Ideal Chemistry_, p. 56.]

_Dr. T. Sterry Hunt on the pre-nebular condition of matter._—A year

after the foregoing views regarding chemical dissociation had been

advanced by Sir Benjamin Brodie, Dr. T. Sterry Hunt, in a lecture on

“The Chemistry of the Primeval Earth,” delivered at the Royal

Institution (May 31, 1867), put forward, apparently quite independently,

opinions on dissociation similar to those of Brodie. In this lecture he

says: “I considered the chemistry of nebulæ, sun, and stars in the

combined light of spectroscopic analysis and Deville’s researches on

dissociation, and concluded with the generalisation that the breaking-up

of compounds, or dissociation of elements, by intense heat is a

principle of universal application, so that we may suppose that all the

elements which make up the sun, or our planet, would, when so intensely

heated as to be in the gaseous condition which all matter is capable of

assuming, remain uncombined, that is to say, would exist together in the

state of chemical elements, whose further dissociation in stellar or

nebulous masses may even give us evidence of matter still more elemental

than that revealed in the experiments of the laboratory, where we can

only conjecture the compound nature of many of the so-called elementary

substances.”[70] And in his address at the grave of Priestley he

referred to the suggestion of Lavoisier that hydrogen, nitrogen, and

oxygen, with heat and light, might be regarded as simpler forms of

matter from which all others are derived. This suggestion was considered

in connection with the fact that the nebulæ, which we conceive to be

condensing into suns and planets, have hitherto shown evidences only of

the presence of the first two of these elements, which, as is well

known, make up a large part of the gaseous envelope of our planet, in

the forms of air and aqueous vapour. With this he connected the

hypothesis advanced by Grove, “that our atmosphere and ocean are but

portions of the universal medium which, in an attenuated form, fills the

interstellary spaces;[71] and further suggested as a legitimate and

plausible speculation that these same nebulæ and their resulting worlds

_may be evolved by a process of chemical condensation from this

universal atmosphere_, to which they would sustain a relation somewhat

analogous to that of clouds and rain to the aqueous vapour around us.”

[Footnote 70: _American Journal of Science_, vol. xxiii. p. 124.]

[Footnote 71: “Our atmosphere,” says Dr. Hunt, “is not terrestrial, but

cosmical, being a universal medium diffused throughout all space, but

condensed around the various centres of attraction in amount

proportional to their mass and temperature, the waters of the ocean

themselves belonging to this universal atmosphere.” (_Nature_, August

29, 1878, p. 475.) Similar views have been advocated by Mr. Mattieu

Williams, who says “that the gaseous ocean, in which we are immersed, is

but a portion of the infinite atmosphere that fills the whole solidity

of space; that links together all the elements of the universe, and

diffuses among them their heat and light, and all the other physical and

vital forces which heat and light are capable of generating.” (_Fuel of

the Sun_, p. 5.) In 1854 Sir William Thomson suggested the idea that the

luminiferous ether was probably a continuation of our atmosphere, though

I do not think he continues to hold that opinion. The first to advance

this idea was, undoubtedly, Newton, who assumed interplanetary space to

be universally filled with an ethereal medium “much of the same

constitution as air, but far rarer, subtler, and more elastic.”]

_Professor Oliver Lodge on the pre-nebular condition of matter._—Some

have gone still farther back and supposed that the material universe may

have arisen out of the luminiferous ether—the hypothetical medium which

is assumed to pervade all space. The universal world-stuff scattered

through boundless space may in an extreme state of attenuation be, says

Professor Winchell, the ethereal medium, and out of this semi-spiritual

substance may have germinated the molecules of common matter. “It is

certainly possible,” he says, “to conceive these cosmical atoms as a

rising-out of some transformation of the ethereal medium; but we know

too little of the nature of ether to ground a scientific inference of

this kind.”[72]

[Footnote 72: _World Life_, p. 533.]

The ethereal origin of matter has been advocated by M. Saigey, Dr.

Macvicar, and others. In a lecture by Professor Oliver Lodge, delivered

at the London Institution in December 1882, he also advocates the

ethereal origin of matter. “As far as we know,” to state his views in

his own words, “this ether appears to be a perfectly homogeneous,

incompressible, continuous body, incapable of being resolved into simple

elements or atoms; it is, in fact, continuous, not molecular. There is

no other body of which we can say this, and hence the properties of

ether must be somewhat different from those of ordinary matter.” ...

“One naturally asks, is there any such clear distinction to be drawn

between ether and matter as we have hitherto tacitly assumed? May they

not be different modifications, or even manifestations, of the same

thing?” He then adopts Sir William Thomson’s theory of vortex atoms,

into the details of which I need not here enter. In conclusion, says

Professor Lodge, “I have now endeavoured to introduce you to the

simplest conception of the material universe which has yet occurred to

man—the conception that it is of one universal substance, perfectly

homogeneous and continuous, and simple in structure, extending to the

farthest limits of space of which we have any knowledge, existing

equally everywhere: some portions either at rest or in simple

irrotational motion, transmitting the undulations which we call light;

other portions in rotational motion—in vortices, that is—and

differentiated permanently from the rest of the medium by reason of this

motion.

“These whirling portions constitute what we call matter; their motion

gives them rigidity, and of them our bodies and all other material

bodies with which we are acquainted are built up.

“One continuous substance filling all space, which can vibrate as light;

which can be sheared into positive and negative electricity; which in

whirls constitutes matter; and which transmits by continuity, and not by

impact, every action and reaction of which matter is capable. This is

the modern view of ether and its functions.”[73]

[Footnote 73: _Nature_, February 1, 1883, p. 330.]

There is this objection to Professor Lodge’s theory: it is purely

hypothetical. The vortex atoms are not only hypothetical, but the

substance out of which these atoms are assumed to be formed is also

itself hypothetical. We have no certain evidence that such a medium as

is thus supposed exists, or that a medium possessing the qualities

attributed to it could exist. In fact, we have here one hypothesis built

upon another.

The vortex theory appears to me to be beset by a difficulty of another

kind, viz. that of reconciling it with the First Law of Motion.

According to that law no body possessing inertia can deviate from the

straight line unless forced to do so. A planet will not move round the

sun unless it be constantly acted upon by a force deflecting it from the

straight path. A grindstone will not rotate on its axis unless its

particles are held together by a force preventing them from flying off

at a tangent to the curve in which they are moving. Centrifugal force

must always be balanced by centripetal force. The difficulty is to

understand what force counterbalances the centrifugal force of the

rotating material of the vortex-atom. It is not because the centrifugal

tendency of the rotating material is controlled by the exterior

incompressible fluid, for it offers no resistance whatever to the

passage of the atom through it—in short, in so far as the motion of the

atom is concerned, this fluid is a perfect void. Now, if this fluid can

offer no resistance to the passage of the atom as a whole, how then does

it manage to offer such enormous resistance to the materials composing

the atom, so as to continually deflect them from the straight path and

compel them to move in a curve? The centrifugal force of these

vortex-atoms must be enormous, for on it is assumed to depend the

hardness or resistance of matter to pressure. Now the centripetal force

which balances this centrifugal force must be equally enormous. If,

then, this perfect fluid outside the vortex-atom can exert this enormous

force on the revolving material without being itself possessed of

vortex-motion, there does not seem to be any necessity for vortex-motion

in order to produce resistance. In short, how is the existence of the

atom possible under the physical conditions assumed in the theory? How

this may be, like the space of four dimensions, may be expressed in

mathematical language, but like it, I fear, it is unthinkable as a

physical conception.

_Mr. William Crookes on the pre-nebular condition of matter._—In his

opening address before the Chemical Section of the British Association

in 1886, Mr. William Crookes entered at considerable length into the

question of the genesis and evolution of the chemical elements. I shall

here give a brief statement of his views as embodied in his important

address, and this I shall endeavour to do as nearly as possible in Mr.

Crookes’s own words.

“We ask,” says Mr. Crookes, “whether the chemical elements may not have

been evolved from a few antecedent forms of matter—or possibly from only

one such—just as it is now held that all the innumerable variations of

plants and animals have been developed from fewer and earlier forms of

organic life: built up, as Dr. Gladstone remarks, from one another

according to some general plan. This building up, or evolution, is above

all things not fortuitous: the variation and development which we

recognise in the universe run along certain fixed lines which have been

preconceived and foreordained. To the careless and hasty eye design and

evolution seem antagonistic; the more careful inquirer sees that

evolution, steadily proceeding along an ascending scale of excellence,

is the strongest argument in favour of a preconceived plan.”

Now, as in the organic world, so in the inorganic, it seems natural to

view the chemical elements not as primordial, but as the gradual outcome

of a process of development, possibly even of a struggle for existence.

But this evolution of the elements must have taken place at a period so

remote as to be difficult to grasp by the imagination, when our earth,

or rather the matter of which it consists, was in a state very different

from its present condition. The epoch of elemental development, remarks

Mr. Crookes, is decidedly over, and it may be observed that in the

opinion of not a few biologists the epoch of organic development is

verging upon its close.

Is there then, in the first place, any direct evidence of the

transmutation of any supposed “element” of our existing list into

another, or of its resolution into anything simpler? To this question

Mr. Crookes answers in the negative.

We find ourselves thus driven to indirect evidence—to that which we may

glean from the mutual relations of the elementary bodies. First, we may

consider the conclusion arrived at by Herschel, and pursued by

Clerk-Maxwell, that atoms bear the impress of manufactured articles. “A

manufactured article may well be supposed to involve a manufacturer. But

it does something more: it implies certainly a raw material, and

probably, though not certainly, the existence of by-products, residues,

paraleipomena. What or where is here the raw material? Can we detect any

form of matter which bears to the chemical elements a relation like that

of a raw material to the finished product, like that, say, of coal-tar

to alizarin? Or can we recognise any elementary bodies which seem like

waste or refuse? Or are all the elements, according to the common view,

co-equals? To these questions no direct answers are forthcoming.”

_Argument from Prout’s Law._—The bearing of the hypothesis of Prout in

relation to the evolution of the elements is first considered by Mr.

Crookes. If that hypothesis were demonstrated it would show that the

accepted elements are not co-equal, but have been formed by a process of

expansion or evolution. According to this hypothesis the atomic weights

of the elements are multiples by a series of whole numbers of the atomic

weight of hydrogen. It is true that accurate determinations of the

atomic weights of different elements do not by any means harmonise with

the values which Prout’s Law requires; nevertheless the agreement in so

many cases is so close that one can scarcely regard the coincidence as

accidental.

The atomic weights have been recalculated with extreme care by Professor

F. W. Clarke, of Cincinnati, and he says that “none of the seeming

exceptions are inexplicable. In short, admitting half-multiples as

legitimate, it is more probable that the few apparent exceptions are due

to undetected constant errors than that the great number of close

agreements should be merely accidental.” In reference to this suggestion

of Professor Clarke, Mr. Crookes thinks that it places the matter upon

an entirely new basis. For, suppose the unit atom to be not hydrogen,

but some element of still lower atomic weight, say _helium_, an element

supposed by many authorities to exist in the sun and other stellar

bodies—an element whose spectrum consists of a single ray, and whose

vapour possesses no absorbent power, which indicates a remarkable

simplicity of molecular constitution. Granting that helium exists, all

analogy points, says Mr. Crookes, to its atomic weight being below that

of hydrogen; and here, then, we have the very element with atomic weight

half that of hydrogen required by Professor Clarke as the basis of

Prout’s Law.

_Argument from the earth’s crust._—The probable compound nature of the

chemical elements, Mr. Crookes thinks, is better shown by a

consideration of certain peculiarities in their occurrence in the

earth’s crust. “We do not,” he says, “find them evenly distributed

throughout the globe. Nor are they associated in accordance with their

specific gravities: the lighter elements placed on or near the surface,

and the heavier ones following serially deeper and deeper. Neither can

we trace any distinct relation between local climate and mineral

distribution. And by no means can we say that elements are always or

chiefly associated in nature in the order of their so-called chemical

affinities: those which have a strong tendency to form with each other

definite chemical combinations being found together, whilst those which

have little or no such tendency exist apart. We certainly find calcium

as carbonate and sulphate, sodium as chloride, silver and lead as

sulphides; but why do we find certain groups of elements, with little

affinity for each other, yet existing in juxtaposition or commixture?”

As instances of such grouping he mentions nickel and cobalt; the two

groups of platinum metals; and the so-called “rare earths,” existing in

gadolinite, samarskite, &c. Why, then, are these elements so closely

associated? What agency has brought them together? It cannot be

considered that nickel and cobalt have been deposited in admixture by

organic agency; nor yet the groups of iridium, osmium, and platinum;

ruthenium, rhodium, and palladium.

These features, Mr. Crookes thinks, seem to point to their formation

severally from some common material placed in conditions in each case

nearly identical.

_Argument from the compound radicals._—A strong argument in favour of

the compound nature of the elements, Mr. Crookes thinks, is derived from

a consideration of their analogy to the compound radicals, or

pseudo-elements as they might be called. It may be fairly held that if a

body known to be compound is found behaving as an element, this fact

lends plausibility to the supposition that the elements are not

absolutely simple. From a comparison of the physical properties of

inorganic with those of organic compounds, Dr. Carnelley concluded that

the elements, as a whole, are analogous to the hydrocarbon radicals.

This conclusion, if true, he added, should lead to the further inference

that the so-called elements are not truly elementary, but are made up of

at least two absolute elements, which he named provisionally A and B.

In Dr. Carnelley’s scheme all the chemical elements save hydrogen are

supposed to be composed of two simpler elements, A = 12 and B = 2. Of

these he regards A as a tetrad identical with carbon, and B as a monad

of negative weight; perhaps the ethereal fluid of space. His three

primary elements are, therefore, carbon, hydrogen, and the ether.

_Argument from polymerisation._—The polymeristic theory of the genesis

of the chemical elements propounded by Dr. Mills falls next to be

considered.

It has been suggested by Dr. E. J. Mills that the pristine matter was

once in an intensely heated condition, and that it has reached its

present state by a process of free cooling, and that the elements, as we

now have them, are the result of successive polymerisations. Chemical

substances in cooling naturally increase in density, and we sometimes

observe that as the density increases there are critical points

corresponding to the formation of new and well-defined substances. The

bodies thus formed are known as polymers. From a study of the

classification of the elements Mr. Mills is of opinion that the only

known polymers of the primitive matter are arsenic, antimony, and

perhaps erbium and osmium.

_Argument from the Periodic Law._—Lastly a scheme of the origin of the

elements, suggested to Mr. Crookes by consideration of Professor

Reynolds’s method of illustrating the periodic law of Newlands, is

discussed.

It was pointed out by Newlands that atomicity and other properties of

some of the chemical elements depend on the order in which their atomic

weights succeeded one another; and when this law was extended by

Professor Mendelejeff to all elements it was apparent that a

mathematical relation exists between the elements. This far-reaching law

has been fruitful of results. Referring to Professor Reynolds’s diagram

illustrating the law, Mr. Crookes says: “The more I study the

arrangement of this zigzag curve, the more I am convinced that he who

grasps the key will be permitted to unlock some of the deepest mysteries

of creation. Let us imagine if it is possible to get a glimpse of a few

of the secrets here hidden. Let us picture the very beginnings of time,

before geological ages, before the earth was thrown off from the central

nucleus of molten fluid, before even the sun himself had consolidated

from the original _protyle_.[74] Let us still imagine that at this

primal stage all was in an ultra-gaseous state, at a temperature

inconceivably hotter than anything now existing in the visible universe;

so high, indeed, that the chemical atoms could not yet have been formed,

being still far above their dissociation-point. In so far as _protyle_

is capable of radiating or reflecting light, this vast sea of

incandescent mist, to an astronomer in a distant star, might have

appeared as a nebula, showing in the spectroscope a few isolated lines,

forecasts of hydrogen, carbon, and nitrogen spectra.

[Footnote 74: _Protyle_ is the term adopted by Mr. Crookes to designate

the original primal matter existing before the evolution of the chemical

elements, and out of which they were evolved. Protyle in chemistry is

analogous to _protoplasm_ in biology, with this difference, however,

that protyle is as yet hypothetical, whereas protoplasm is known to be

real.]

“But in course of time some process akin to cooling, probably internal,

reduces the temperature of the cosmic _protyle_ to a point at which the

first step in granulation takes place; matter as we know it comes into

existence, and atoms are formed. As soon as an atom is formed out of

_protyle_ it is a store of energy, potential (from its tendency to

coalesce with other atoms by gravitation or chemically) and kinetic

(from its internal motions). To obtain this energy, the neighbouring

_protyle_ must be refrigerated by it, and thereby the subsequent

formation of other atoms will be accelerated. But with atomic matter the

various forms of energy which require matter to render them evident

begin to act; and, amongst others, that form of energy which has for one

of its factors what we now call _atomic weight_. Let us assume that the

elementary _protyle_ contains within itself the potentiality of every

possible combining proportion or atomic weight. Let it be granted that

the whole of our known elements were not at this epoch simultaneously

created. The easiest formed element, the one most nearly allied to the

_protyle_ in simplicity, is first born. Hydrogen—or shall we say

helium?—of all the known elements the one of simplest structure and

lowest atomic weight, is the first to come into being. For some time

hydrogen would be the only form of matter (as we know it) in existence,

and between hydrogen and the next formed element there would be a

considerable gap in time, during the latter part of which the element

next in order of simplicity would be slowly approaching its birth-point:

pending this period we may suppose that the evolutionary process, which

soon was to determine the birth of a new element, would also determine

its atomic weight, its affinities, and its chemical position.”

_Professor F. W. Clarke on the pre-nebular condition of matter._—Views

on elemental evolution almost similar to those of Mr. Crookes’s have

been advocated by Professor Clarke. Spectroscopic phenomena, says

Professor Clarke, are quite in harmony with the idea that all matter is

at bottom one, our supposed atoms being really various aggregations of

the same fundamental unit.

“Everybody knows that the nebular hypothesis, as it is to-day, draws its

strongest support from spectroscopic facts. There shine the nebulæ in

the heavens, and the spectroscope tells us what they really are, namely,

vast clouds of incandescent gas, mainly, if not entirely, hydrogen and

nitrogen. If we attempt to trace the chain of evolution through which

our planet is supposed to have grown, we shall find the sky is full of

intermediate forms. The nebulæ themselves appear to be in various stages

of development; the fixed stars or suns differ widely in chemical

constitution and in temperature; our earth is most complex of all. There

are no ‘missing links’ such as the zoologist longs to discover when he

tries to explain the origin of species. First, we have a nebula

containing little more than hydrogen, then a very hot star with calcium,

magnesium, and one or two other metals added; next comes a cooler sun in

which free hydrogen is missing, but whose chemical complexity is much

increased; at last we reach the true planets with their multitudes of

material forms. Could there well be a more straightforward story? Could

the unity of creation receive a much more ringing emphasis? We see the

evolution of planets from nebulæ still going on, and parallel with it an

evolution of higher from lower kinds of matter.

“Just here, perhaps, is the key to the whole subject. If the elements

are all in essence one, how could their many forms originate save by a

process of evolution upward? How could their numerous relations with

each other, and their regular serial arrangements into groups, be better

explained? In this, as in other problems, the hypothesis of evolution is

the simplest, most natural, and best in accordance with facts.”[75]

[Footnote 75: _Popular Science Monthly_ for February 1876. See also the

January number for 1873.]

_Dr. G. Johnstone Stoney on the pre-nebular condition of

matter._—Further evidence that all the chemical elements were probably

evolved from one common source, is furnished by Dr. G. Johnstone

Stoney’s “Logarithmic Law of Atomic Weights,” a theory recently advanced

in a communication to the Royal Society.[76] A cardinal feature of this

investigation is that in it atomic weights are represented by volumes,

not by lines. A succession of spheres are taken whose volumes are

proportional to the atomic weights, and which may be called _the atomic

spheres_. When the radii of these spheres are plotted down on a diagram

as ordinates, and a series of integers as abscissas, the general form of

the logarithmic curve becomes apparent; and close scrutiny has shown

that either the logarithmic curve, or some curve lying very close to it,

expresses the real law of nature.

[Footnote 76: _Proc. Roy. Soc._ for April 19, 1888, p. 115.]

If, as seems probable, the logarithmic law is the law of nature, there

appear to be three elements lighter than hydrogen, which Dr. Stoney has

termed infra-fluorine, infra-oxygen, and infra-nitrogen. And there are,

at all events, six missing elements between hydrogen and lithium.

Dr. Stoney’s investigation is based on the fact that if the atomic

weights of the chemical elements be arranged in order of magnitude,

periodic laws come to light, viz.: those discovered by Newlands,

Mendelejeff, and Meyer. From this it follows that there must be some law

connecting the atomic weights with the successive terms of a numerical

series—either alone or along with other variables.

“This law,” says Dr. Stoney, “may be obtained in one of its graphical

forms by plotting down a series of integers as abscissas, and the

successive atomic weights as ordinates. In this way it furnishes a

diagram which has somewhat the shape of a hurling-stick, consisting of a

short curved portion succeeded by a long and nearly straight portion.

But as this diagram cannot be directly identified with any known curve,

it does not suffice for the determination of the law.

“The diagram, however, assumes a form which can be interpreted when we

use the cube roots of the atomic weights for its ordinates, instead of

the atomic weights themselves. This is equivalent to taking volumes

instead of lines to represent the atomic weights. When this is done, the

ends of the ordinates are found to lie near a regular and gradual curve,

from which they deviate to the right and left by displacements that are

small and appear to follow periodic laws which have been in part traced.

The central curve is found on examination to be either a logarithmic

curve or some curve lying exceedingly close to it. If the curve be in

reality the logarithmic curve, it furnishes us the law that:

“The cube root of the n^{th} atomic weight = κ log (n q) + a small

periodic correction; where κ and q are constants, the values of which

are furnished by the observations.

“Either this logarithmic law, or a law that lies exceedingly close to

it, must be the law of nature.”

Referring to this theory, Professor Reynolds says: “It certainly

introduced points of extraordinary importance, though perhaps at present

they could not all quite realise its fullest import. There were several

points of some little difficulty to be grappled with, but it clearly

pointed to the conclusion that we were fast approaching the time when

physicists—both chemical and physicists proper—are combining to evolve

out of the scientific work lying on the borderland most important and

startling facts.”

The bearing which Dr. Stoney’s conclusions, like those of Mr. Crookes,

have on the primitive condition of the material universe is obvious.

Dr. Stoney, like Mr. Crookes, considers that the chemical elements are

subject to decay. That they are not only generated but destroyed—that

they are subject not only to evolution but dissolution. He believes that

the generative process probably takes place only at, or beyond, the

confines of the universe, and the destructive process at the centres of

overgrown stars, which is the position of lowest potential. Dr. Stoney

thinks that this extinction of the chemical elements in the centre of a

star is a cause which limits its size and prevents its overgrowth.

THE IMPACT THEORY IN RELATION TO THE FOREGOING THEORIES OF THE

PRE-NEBULAR CONDITION OF MATTER.

In all these theories, as has already been observed, the primitive

condition of the universe was that of matter in a state of extreme

tenuity, while by aggregation the materials became successively larger

and larger until they assumed the magnitude of suns and planets. For

example, according to the meteoric theory, meteorites are formed out of

“cosmical dust,” “fire-mist,” or condensed vapour, and then suns and

planets are formed by aggregation from these meteorites. Facts seem,

however, to point to the very reverse as being the true course of

events.

Meteorites are undoubtedly the fragments of larger masses. It looks more

likely that they are, as has already been stated, fragments of stellar

masses which have been shattered to pieces by collision, and that this

“cosmical dust,” from which the meteorites are alleged to have been

formed, are simply the dust arising out of the destruction of the

masses. After the two bodies had collided and been shattered to pieces,

some of the fragments would undoubtedly be projected with a velocity

that would carry them beyond the attractive power of the general mass,

and thus they would escape being volatilised. These fragments would

continue their wanderings through space as meteorites.

I cannot but think that the number, as well as the importance, of these

wanderers has been greatly over-estimated. Mr. Lockyer states that Dr.

Schmidt, of Athens, found that the mean hourly number of luminous

meteors visible on a clear moonless night by one observer was fourteen.

Certainly no such quantity is visible in this country. In Scotland, at

least, one may often watch night after night under the most favourable

conditions without having the good fortune to see a single meteor.

It is, of course, true that the immediately prior condition of a sun or

a planet was that of matter in an extremely attenuated or dissociated

state. This is essential to the nebular, as well as to the meteoric,

hypothesis. But it is not with the immediately prior condition that we

are at present concerned, but with the primitive, or pre-nebular,

condition. Take, for example, the case of the solar nebula, out of which

our sun and planets were formed. Was this nebulous mass formed from

matter in a state of extreme tenuity, scattered through space and

collected together by gravity? Or did it result from two solid globes

shattered to pieces by collision, which were then converted into the

nebulous condition by the heat generated from the collision? It is no

doubt true that the analogies of nature would, at first sight, be apt to

lead us to the conclusion that the former theory was the more likely of

the two, as the larger is generally made by aggregation from the

smaller. But a little consideration will show that, in the present case,

the weight of this analogy is more apparent than real. The impact theory

does not rest upon a purely hypothetical basis. The cause to which it

appeals has a real existence. The point of uncertainty is whether the

cause actually produces the effect which is attributed to it. We know

from observation that there are stellar masses, some of them probably

larger than our sun, moving through space with enormous velocities in

all directions.[77] According to the ordinary laws of chance, collision

at times would be an inevitable result, and when such an event did take

place the destruction of the colliding bodies, and their consequent

transformation into a nebulous mass, would, at least in many cases, be a

_necessary_ result. In fact, we have, in the case of these vast stellar

masses, what we know occurs among the invisible molecules of a gas. So

far as mere analogy is concerned, the impact theory is just about as

probable as the other.

[Footnote 77: The dark stellar masses which escape observation may be as

numerous as those that are visible.]

From what has been stated it would follow that in most cases the stellar

masses have been formed out of the destruction of pre-existing masses,

like the geological formations out of the destruction of prior

formations.

_The theories do not account for the motion of the stars._—According to

all the foregoing theories aggregation and condensation are produced by

gravity. The materials dispersed throughout space are drawn together by

their mutual attraction, and aggregated round a centre of gravity.

Gravitation, although it imparts motion to the materials, can impart no

motion of translation to the mass itself. Gravitation cannot, therefore,

be the cause of the motion of translation of the mass. The stars are not

supposed to be gravitating towards, or around, a great centre of

attraction, for they are found moving in straight lines in all

directions, which could not be the case if gravity were the cause of

their motion. To what cause is their motion, therefore, to be

attributed? A meteorite or other small body might be ejected from any

system, by the explosive force of heat or some other cause, with a

velocity which might carry it into boundless space; but such could not

be the case in regard to a body of the magnitude of a star. No one for a

moment could suppose that 1830 Groombridge, for example, moving at the

rate of 200 miles a second, is an eject from any system.

According to the impact theory the whole is plain; for this 200 miles

per second is simply a part of the untransformed motion of translation

which the materials composing the star had from the beginning. In other

words, the matter and the motion were eternal, or, what is more

probable, as will afterwards be seen, co-existed from creation—not,

however, as molecular motion, but as motion of the mass.

_The theories do not account for the amount of heat required._—It has

been shown that, although the materials of our solar system had fallen

together from an infinite distance, it could not have generated heat

sufficient to have formed a gaseous nebula extending to the distance of

the planet Neptune. Gravitation alone could not, therefore, have been

the source from which the nebula obtained its heat. The solar nebula,

however, must originally have extended far beyond the orbit of Neptune.

But supposing it could be demonstrated that the heat thus generated was

sufficient to have formed a nebula extending to even twice the distance

of Neptune, this would not remove the fatal objection to the gravitation

theory of the origin of the solar nebula. For the facts, both of geology

and of biology, equally show that the sun has been radiating his heat at

the present rate for more than twice the length of time that it could

possibly have done had gravitation been the source from which the energy

was derived. This objection is alike fatal to the meteoric theory as it

is to all other theories which attribute the origin and source of the

heat to gravitation.

_Evolution of matter._—Our inquiries into stellar evolution do not,

however, begin with the consideration of a gaseous nebula, or with

swarms of meteorites. There was a pre-nebular evolution. The researches

of Prout, Newlands, Mendelejeff, Meyer, Dumas, Clarke, Lockyer, Crookes,

Brodie, Hunt, Graham, Deville, Berthelot, Stoney, Reynolds, Carnelley,

Mills, and others, clearly show, I think, that the very matter forming

this nebulous mass passed through a long anterior process of evolution.

And not only the matter, but the very elements themselves constituting

the matter, were evolved out of some prior condition of substance.

I have already given at some length the views which have been advanced

by several of our leading physicists and chemists on the evolution of

the chemical elements, and on some of the bearings which these views

have on stellar evolution. I shall now briefly refer to a point on which

I venture to think the theory discussed in this volume seems to cast

some additional light.

If the elements were evolved out of a common source, there is, in order

to this, one necessary condition, viz. an excessively high temperature;

for the temperature must be above the point of the dissociation of all

the chemical elements. “In the primal stage of the universe,” says Mr.

Crookes, “before matter, as we now find it, was formed from the protyle,

all was in an ultra-gaseous state, at a temperature inconceivably hotter

than anything now existing in the visible universe; so high, indeed,

that the chemical atoms could not yet have been formed, being still far

above their dissociation point.”

What, then, produced this excessive temperature in this supposed

ultra-gaseous protyle? It could not have resulted from condensation by

gravity. In condensation the heat increases as the condensation

proceeds, because it is the condensation which produces the heat. But

here the reverse must have been the case, for the ultra-gaseous mass was

much hotter than the sun which was afterwards formed out of it. It was,

according to Mr. Crookes, when this gaseous mass cooled down, so as to

permit of its becoming converted into solid matter, that condensation

into a sun could take place. Besides, was it not the excessive heat

which produced the assumed ultra-gaseous condition?

There is another difficulty besetting the theory that the primitive heat

was derived from condensation by gravitation. Supposing we should assume

it possible that the protyle could exist in this ultra-gaseous state

without possessing temperature, and that it obtained its heat from

condensation by gravity, then the fact of condensation taking place

shows that the gas was not in a state of equilibrium. But the gas could

not have remained stationary for a single moment without beginning to

condense while in a condition of unstable equilibrium. We must therefore

conclude that the gas must have been in some other condition than the

gaseous state prior to condensation.

The impact theory seems to remove all these difficulties. It is just as

likely _à priori_, if not more so, that the primitive form of the

protyle should have been that of large cold masses moving through space

in all directions, with excessive velocities, as that it should have

been that of a gaseous mass in a state of unstable equilibrium. If we

assume the former condition, then the colliding of these masses would

account not only for the ultra-gaseous state, but also for its

inconceivably high temperature. Besides, in this case we are not called

upon to account for any other antecedent state of the masses before

collision, for they may have existed from the beginning of creation in

the form of masses in motion through space.

Had space and time permitted, it might have been shown that there are

other obscure points on which the theory seems to shed additional light.

I shall now, in conclusion, refer to a point wherein the theory differs

radically from that of all other theories of stellar evolution. But

before doing so I may briefly refer to an objection which has been

frequently urged against the theory.

_Objection considered._—The objection to which I refer is this, that,

had the nebulæ been produced by impact in the way implied in the theory,

then we ought to have had some historical record of such an event. I can

perceive no force in such an objection. Our historical records, I

presume, do not extend much farther back than about 3,000 years, and we

have no evidence to conclude that a new nebula makes its appearance in

the visible firmament with such frequency; and supposing it did, we have

no grounds for assuming that its production by impact in the way

supposed by the theory would attract general notice. It is doubtful if

the nebula produced would, in the first instance, be actually visible. I

have shown that the temperature of the nebula could not have been less

than about 300,000,000° C., and it is very doubtful if the gaseous mass

enveloping all that was solid in the nebula would, at such a

temperature, be self-luminous. The probability is that all the chemical

elements composing it would be in a state of utter dissociation, and

converted back into the original protyle from which they were derived,

again to be slowly reconverted into their former atomic condition as the

temperature fell.

_Can we on scientific grounds trace back the evolution of the universe

to an absolute first condition?_—As has been repeatedly stated, all

inquiries into the evolutionary history of the stellar universe begin in

the middle of a process. Evolution is a process. The changes that now

occur arose out of preceding changes, and these, preceding changes out

of changes still prior, and so on indefinitely back into the unknown

past. This chain of causation—this succession of change—of consequent

and antecedent—could not in this manner have extended back to infinity,

or else the present stage of the universe’s evolution ought to have been

reached infinite ages ago. The evolution of things must therefore have

had a beginning in time. Professor Winchell, in his final generalisation

to his work, “World Life,” has stated this matter so clearly and

forcibly that I cannot do better than here quote his words on the

subject.

“We have not,” says Professor Winchell, “the slightest scientific

grounds for assuming that matter existed in a certain condition from all

eternity, and only began undergoing its changes a few millions or

billions of years ago. The essential activity of the powers ascribed to

it forbids the thought. For all that we know—and, indeed, as the

_conclusion_ from all that we know—primal matter began its progressive

changes on the morning of its existence. As, therefore, the series of

changes is demonstrably finite, the lifetime of matter itself is

necessarily finite. There is no real refuge from this conclusion; for,

if we suppose the beginning of the present cycle to have been only a

restitution of an older order effected by the operations of natural

causes, and suppose—what science is unable to comprehend—that older

order to be a similar re-inauguration, and so on indefinitely through

the past, we only postpone the predication of an absolute beginning,

since, by all the admissions of modern scientific philosophy, it is a

necessity of nature to run down.”

These are consequences which necessarily follow from every theory of

stellar evolution which has hitherto been advanced. The impact theory,

however, completely removes the difficulty, for according to it the

evolutionary process can, on purely scientific grounds, be traced back

to an absolute beginning in time. If huge solid masses moving through

space were the original condition of the universe, then, in so far as

either philosophy or science can demonstrate to the contrary, it might

have been in this condition from all eternity. We are therefore not

called upon to account for this primitive condition of things. Now it is

evident, unless a collision should take place, the universe would remain

in this condition for ever: without a collision there could be no

change, no work performed, and absolutely no loss or gain of energy, and

therefore no process of evolution. The first collision would be the

absolute commencement of evolution—the beginning of the process of the

development of the universe. Evolution would, in this case, have its

absolute beginning in time, and consequently was not eternal. If, on the

other hand, we assume, what is far more in harmony with physics,

metaphysics, and common sense, that the universe was created in time, we

are still led to the same result as to an absolute commencement of

evolution. In both cases we reach a point beyond which there can be no

legitimate inquiry; no further question which the scientists can

reasonably ask.

We have no grounds to conclude that there is anything eternal, except

God, Time, and Space. But if time and space be subjective, as Kant

supposes, and not modes pertaining to the existence of things in

themselves, then God alone was uncreated, and _of_ Him and _to_ Him are

all things.

------------------------------------------------------------------------

------------------------------------------------------------------------

INDEX.

Aqui Range, Utah, fault in, 57

Arcturus, motion of, 16

Atmosphere, universal, 82

„ Dr. Hunt on, 86

„ Mr. Mattieu Williams on, 86

Atomic weights, logarithmic law of, 100

Atoms, according to Herschel and Clerk-Maxwell, manufactured articles,

92

Binary systems, 32

„ Dr. Johnstone Stoney on, 33

„ Sir W. Thomson on, 33

Biology, testimony of, as to age of sun’s heat, 65

Brodie, Sir B., on the pre-nebular condition of matter, 84

Brown and Dickson on sediment of the Mississippi, 40

Carnelley, Dr., argument from compound radicals, 94

μ Cassiopeiæ, motion of, 16

α Centauri, distance of, 16

Chemical elements, evolution of, 80

Clarke, Prof. F. W., on atomic weights, 93

„ on evolution of the chemical elements, 80, 89

„ on the pre-nebular condition of matter, 98

Comets, according to Laplace, strangers to our system, 17

„ according to Prof. A. Winchell, strangers to our system, 17

„ M. Faye on origin of, 17

„ probable origin of, 17

Compound radicals, argument from, 95

Condensation in relation to nebulæ, 27

„ the last condition of a nebula, 30

Cosmical dust and “fire-mist,” 81, 102

Crookes, Mr. W., on the pre-nebular condition of matter, 90-98

„ on _protyle_, 96

61 Cygni, motion of, 16

Darwin, Mr. Charles, on geological time, 67

Denudation, age of the globe as represented by, 63, 64

„ average rate of whole globe, 44

„ evidence from faults as to rate of, 53

„ Dr. A. Geikie on rate of, 41

„ glacial epochs in relation to, 46, 47

„ in Colorado, 58

„ in past ages not much greater than at present, 44

„ method employed to estimate its rate, 39, 47

„ Mr. A. R. Wallace’s method of estimating its rate, 51

„ of Bristol coal-fields, 59

„ of Mississippi basin, Sir Charles Lyell on, 44

„ of Pendle Range, 60

„ of Pentlands, 59

„ of river basins, 41

„ of South of Scotland, 55

„ of Wales, 59

„ Prof. Haughton’s method of estimating its rate, 50

„ Rotation of the earth in relation to, 46

„ the direct method of estimating its rate, 52

„ time required to effect the amount of, 63

Dewar and Liveing on dissociation of chemical elements, 83

Dissociation of chemical elements, Dr. T. Sterry Hunt on, 82, 85

„ of chemical elements, M. Berthelot on, 83

„ of chemical elements, M. Deville on, 83

„ of chemical elements, Mr. Lockyer on, 82

„ of chemical elements, Profs. Liveing and Dewar on, 83

„ of chemical elements, Prof. Schuster on, 83

„ of chemical elements, Sir B. Brodie on, 82, 84

„ Dumas, M., on essential unity of matter, 83

Earth’s crust, argument from, 93

„ rotation, its influence on denudation, 46

Emmons, Mr. S. F., on a fault in Aqui Range, 58

Energy existing as motion of stellar masses, 3

„ transformed by collision, 3

Evolution, can it be traced back to a first condition? 110

„ evidence of, from the grouping of the stars, 81

„ from smaller to larger aggregates of matter, 81

„ of matter, 107

„ of the chemical elements, 80, 107

Faults, evidence of rate of denudation from, 53

„ examples of, 54-60

„ “Grand Wash,” Colorado, 58

„ in East Tennessee, 58

„ in Strathmore, 55

Faye, M., on origin of comets, 17

Gaseous condition essential to the nebular hypothesis, 25

„ state, second condition of a nebula, 24

Geikie, Dr. A., on area of the globe, 48

„ on denudation of the Pentlands, 59

„ on examples of enormous faults, 55

„ on rate of denudation, 41

Geological epochs of past ages, misconceptions regarding, 49

Geological time, Mr. A. R. Wallace on, 65

„ time, Mr. Charles Darwin on, 66

„ time, Prof. Haeckel on, 67

„ time, Prof. Huxley on, 65, 66

„ time, Sir Andrew C. Ramsay on, 67

Geology, testimony of, in regard to age of sun’s heat, 39

Glacial epoch, age of the earth as determined by, 64

„ epochs, influence on denudation, 46

Gravitation does not account for the heat required, 106

„ does not account for motion of the stars, 105

„ insufficient to account for heat of nebulæ, 27

Groombridge 1830, motion of, 15

„ not an eject, 106

„ Prof. Newcomb on motion of, 15

Grove, Sir W. R., on the pre-nebular condition of matter, 78

Haeckel, Prof, on geological time, 67

Haughton, Prof., method of estimating rate of denudation, 50

Heat, age of the sun’s, 37

Helmholtz on age of sun’s heat, 35

Huggins, Mr., and Dr. Miller on spectra of nebulæ with one nitrogen

line, 84

Hull, Prof., on denudation of Pendle Range, 60

„ on examples of enormous faults, 54

Humphreys and Abbot on sediment of the Mississippi, 40

Hunt, Dr. T., on the pre-nebular condition of matter, 85

„ on universal atmosphere, 86

Huxley, Prof., on geological time, 65, 66

Hypothesis, value of, 70

“Impact Theory,” why so called, 2

„ in relation to theories of pre-nebular condition of matter, 102

„ removes difficulties regarding origin of heat, 108, 109

ε Indi, motion of, 16

King, Mr. Clarence, on the Wahsatch Fault, 59

Lalande 21185, motion of, 16

„ 21258, motion of, 16

Laplace, M., on the heat of the solar nebula, 30

Lavoisier, M., on simpler forms of matter, 86

Lesley, Mr. J. P., on a fault in the Appalachians, 57

„ on fault in East Tennessee, 58

Liveing and Dewar on dissociation of chemical elements, 83

Lockyer, Mr., on arrangement of the planets according to density, 25

„ nebulæ with solid matter in a gaseous mass, 20

Lockyer, Mr., on essential condition of solar nebulæ, 25

„ on hypothesis, 70

„ on number of meteorites, 103

„ on outburst of stars, 33

„ on “sorting” of the chemical elements, 25

Lodge, Prof. O., on ethereal origin of matter, 87

„ on the pre-nebular condition of matter, 87

„ on vortex atoms, 88

Logarithmic law of atomic weights, 100

Lyell, Sir Charles, on denudation of the Mississippi basin, 44

Macvicar, Dr., on ethereal origin of matter, 87

Matter not probably eternal, 112

Mendelejeff, Prof., on Periodic Law, 96

Meteorites, number greatly exaggerated, 103

„ probable origin of, 12

„ Sir H. Roscoe on constitution of, 12

„ Sir W. Thomson on, 12

Mill, Mr. J. S., on hypothesis, 70

Miller, Dr., and Mr. Huggins on spectra of nebulæ with one nitrogen

line, 84

Mills, Dr., on Polymerisation, 95

Morris, Mr. Charles, on the pre-nebular condition of matter, 75

Nebulæ, broken fragments in a gaseous mass, 19

„ cometic, 22

„ condensation insufficient to account for heat of, 27

Nebulæ condensation, last condition of, 30

„ first condition of, 19

„ gaseous state, second condition of, 24

„ „ globular, 21

„ heat of, not due to gravitation, 27

„ how they occupy so much space, 18

„ how origin of by impact might not have been observed, 110

„ must possess an excessive temperature, 26

„ Mr. Lockyer on, 20-22

„ origin of, 18

„ Prof. A. Winchell on meteoric origin of, 22

„ Prof. Tait on, 20

„ Sir W. Thomson on origin of, 6, 28

„ spheroidal, 22

„ why of such various shapes, 19

Nebular hypothesis, gaseous condition essential to, 2, 5

Newcomb, Prof., on motion of 1830 Groombridge, 15

Newlands on Periodic Law, 96

Nova Cygni, on sudden outburst of, 33

Objection considered, 109

Palæozoic times, winds probably not higher than at present, 46

Peach, Mr. B. N., on examples of enormous faults, 55

„ on denudation of the south of Scotland, 55

Periodic Law, argument from, 96

„ Prof. Mendelejeff on 96

Periodic Law, Newlands on, 96

„ Prof. Reynolds on, 96

Planets, on their arrangement according to density, 25

Polymerisation, argument from, 95

„ Dr. Mills on, 95

Pouillet, on rate of solar radiation, 2, 35

Powell, Major J. W., on denudation of Uinta Mountains, 58

Pre-nebular condition of matter, Dr. G. Johnstone Stoney on, 99

„ condition of matter, Dr. T. Sterry Hunt on, 85

„ condition of matter, Mr. Charles Morris on, 75

„ condition of matter, Mr. W. Crookes on, 90

„ condition of matter, Prof. A. Winchell on, 71

„ condition of matter, Prof. F. W. Clarke on, 98

„ condition of matter, Prof. Lodge on, 87

„ condition of matter, Sir B. Brodie on, 84

„ condition of matter, Sir W. R. Grove on, 78

„ evolution, 107

Proctor, R. A., on meteoric origin of solar system, 23

_Protyle_, the primal matter, 96

Prout’s Law, argument from, 92

Ramsay, Sir Andrew C, on denudation of Bristol coal-fields, 59

„ on denudation of Wales, 59

„ on geological time, 67

Reynolds, Prof., on Periodic Law 96

Rogers, Prof. H. D., on a great fault in the Appalachian coal-fields,

57

Roscoe, Sir H., on constitution of meteorites, 12

Rotation, supposed influence on denudation, 46

Saigey, M., on ethereal origin of matter, 87

Schmidt, Dr., on number of meteorites, 103

Solar nebula, M. Laplace on heat of, 30

„ Mr. Lockyer on condition essential to, 25

„ Sir W. Thomson on, 6, 28

Solar radiation, rate of, according to Pouillet and Langley, 35

Solar system, Mr. R. A. Proctor on meteoric origin of, 23

Star clusters, 34

Stars, evidence of evolution from their grouping, 81

„ how origin of by impact might not have been observed, 110

„ in four groups, 81

„ motion not accounted for by gravitation, 105

„ motion not due to their mutual attractions, 14

„ motion of, how in straight lines, 14

„ sudden outbursts of, 33

Stoney, Dr. G. Johnstone, on the pre-nebular condition of matter, 99

Subaërial denudation, method of estimating rate of, 39, 47

Sun, age of heat of, 34

Sun’s heat, age of, according to Geology, 37

„ age of, a crucial test, 34, 37

Sun’s heat, age of, according to Thomson and Tait, 35

„ age of, as determined by Biology, 64

„ age of, as determined by Geology, 39

Tait, Prof., nebulæ with solid matter in a gaseous mass, 20

„ on age of sun’s heat, 35

Temperature excessive, essential to nebulæ, 26

„ produced by collision, 5

Thomson, Sir W., on age of sun’s heat, 35

„ on meteorites, 12

„ on origin of solar nebula, 28

„ on solar nebula, 6

„ suggestion by, 86

Tides, supposed influence on denudation, 45

Tycho Brahe, on sudden outburst of a star, 33

Tylor, Alfred, on the denudation of Mississippi Basin, 40

Uinta Mountains, denudation of, 58

„ fault in, 57

Vortex atoms, Prof. Lodge on, 88

“Wahsatch Fault,” Utah, immense dislocation, 58

Wallace, Mr. A. R., on geological time, 65, 68

„ method of estimating rate of denudation, 57

Williams, Mr. Mattieu, on universal atmosphere, 86

Winchell, Prof. A., on age of the earth, 64

„ on comets strangers to our system, 17

„ on denudation of Colorado plateau, 58

„ on deposition of Palæozoic sediment, 45

„ on ethereal medium, 87

„ on meteoric origin of nebulæ, 22

„ on nebular hypothesis, 69

„ on the pre-nebular condition of matter, 71

------------------------------------------------------------------------

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Transcriber’s note:

Front matter, ‘By’ changed from small caps to letter case, “By JAMES

CROLL, LL.D., F.R.S. With”

Page 2, comma inserted after ‘Mag.,’ “Phil. Mag., July 1878;”

Page 25, full stop inserted after ‘Lectures,’ “Manchester Science

Lectures.”

Page 37, heading ‘Testimony...’ changed to small caps.

Page 41, ‘years’ inserted, “Mean        3,378   years”

Page 54, full stop inserted after ‘Mem.,’ “Mem. Geol. Survey of

Lancashire”

Page 59, full stop inserted after ‘vol. i.,’ “Memoirs of Geol. Survey,

vol. i.”

Page 113, ‘radicles’ changed to ‘radicals,’ “argument from compound

radicals”

Page 115, ditto inserted, “„ on examples of enormous faults”

Page 116, ditto inserted, “„ globular”

Page 117, page entries reversed, “of solar radiation, 2, 35”

Page 117, ‘geologica’ changed to ‘geological,’ “on geological time”

Page 118, ditto inserted, “„ fault in, 57”