r suns. Laplace, who was contemporary with Her- schel, seized the thought and carried it out in wider generalization. He saw, in the discov- eries of the great Hanoverian, the basis of a cosmical genealogy. Here was a clew to the formation not only of suns, but also of planets and satellites. Assuming the existence of nebula of such vast magnitude as to fill, spaces equal'to or greater than that occupied by the entire solar system, he fancied that system to have been evolved, by the operation of natural forces, out of that nebulous mass. The Nebular Hypothesis. 21 Notwithstanding the authority of Laplace as a mathematician, astronomers were slow to receive this Nebular Hypothesis. Many nebulce had been resolved. Might not all be similarly constituted, though our instruments were con- fessedly too feeble to resolve them'* After all, may not the nebulce exist only in appearance ? May it not be the blended light of innumerable stars, situated so nearly in the same line of vision that no telescope can ever separate them, and so distant that their light forms but a haze in the open space? We live in more favored times. Great and wonderful as are the results of telescopic ob- servation, the results of Spectrum Analysis are yet more wonderful. By the spectroscope, light itself is translated into a language of revelation, and, as Schellen says, " we are indebted to it for being able to say with certainty that luminous nebula actu- ally exist as isolated bodies in space, and that these bodies are luminous masses of gas." For the purposes of our present inquiry, therefore, we will consider this question set- tled. We assume the existence of real nebulce immense volumes of luminous vapor or gas 22 THE MODERN GENESIS. filling spaces as ample as that occupied by the solar system, or even greater spaces than that. Let us now examine the Nebular Hypoth- esis a little more in detail. Having, by assumption, the original cosmic- al matter existing " at such a temperature as to be in the condition of a vapor of great tenu- ity, stretching across limits wider than the re- motest planet," what have been the processes by which that vapor has been transformed and wrought into our sun and the system of planets that revolve around him ? As we propose to examine the nebular theory in its present phases, we will place it before our readers in the language of its latest expounders and advocates. Professor Winchell enunciates the theory as follows : " The cooling and contracting of this vapor inaugurated a rotation which was inevi- tably accelerated to such an extent that a pe- ripheral ring was detached which became a planet. The same process continued, and other rings were detached, which became planets in due succession. Similarly the plan- etary masses detached rings, which became The Nebular Hypothesis. 23 their satellites. Thus all the marvelous uni- formities of the solar system are but the prog- eny of that primitive impulse which originated the grand rotation. " This doctrine has earned unquestioning acceptance, simply because it accords with all the phenomena ; and the Nebular Hypothesis, for similar reasons, is rapidly taking its place among established doctrines. Many late dis- coveries afford unexpected confirmations ; and there are few physicists at the present time who continue to withhold their assent. Oc- casionally we hear a dissenting voice, but it proceeds almost always from persons who, what- ever may be their eminence in theology or let- ters, have little authority in matters of scien- tific opinion. " Many interesting deductions follow from the nebular origin of the solar system. The older planets are those remote from the sun, and the youngest planet is Mercury; while the sun is only the residual portion of the cosmical mass, still maintaining an inconceivably high temperature, simply because so vast a body of matter has not yet had time to cool off. The planetary bodies, similarly, must have attained 24 THE MODERN GENESIS. to stages of refrigeration determined by the joint influence of age and mass. " It is reasonable to suppose that the older planets are composed of a smaller proportion of the denser elements, since they are formed from peripheral portions of the original fire- mist, while it is likely that the denser portions gathered about the center, and entered to a larger extent into the constitution of later rings. The lower specific gravity of the older plan- ets may be partly attributed to this cause. While Mercury, Venus, and Mars do not vary materially from the density of the Earth, Jupiter, Uranus, and Neptune possess only one fourth of the Earth's density and Saturn but one eighth. This circumstance must have much to do with determining the relative proportions of solid and liquid materials upon the several planets at given temperatures, and is thus con- nected with their adaptability to serve as abodes of organic life." Geology of the Stars. David A. Wells, an author of excellent standing among educators, and editor of the " Annual of Scientific Discovery," presents the theory as follows: " Modern science presents us with only one The Nebular Hypothesis. 2$ hypothesis which, in a consistent and satis- factory manner, attempts to reveal to us the condition of matter, in what may be called the beginning. The outline of this theory, and the evidence upon which it is based, may be briefly stated as follows : " Our solar system, of which the earth is a member, viewed superficially, presents to us the idea of a vast luminous body the sun oc- cupying a central position, with a number of smaller, though various-sized, bodies revolv- ing at different distances around it, some of which, in turn, have smaller planets or satellites revolving about them. "A closer examination, however, makes us acquainted with some very singular peculiar- ities in the structure of this so-called " solar system." Thus, in the first place, it is a very singular fact that the orbits of the planets are all nearly circular, and that their planes are nearly coincident with (or in the same line with) the plane of the sun's equator. " Next, it is not less remarkable that the motions of the planets around the sun, and the satellites around the planets, and, finally, that the motions of all sun, planets, and satellites 26 THE MODERN GENESIS. . around their axes, should be only in one direc- tion, namely, from west to east ; that the periods of revolution grow shorter in the planets and satellites as their distances from their primary grow less ; that the sun rotates on its axis in a shorter period than that employed in the revo- lution of any planet, and that every planet, ac- companied by satellites, rotates on its axis in a less time than the period of revolution of any satellite. "These peculiarities suggested to Laplace, the eminent French astronomer and mathemati- cian, the idea that all the matter of the solar system was once a connected mass, endowed with a uniform motion in one direction. " He further showed, that while this hypoth- esis and its deductions explained fully the peculiarities noticed, they were not accounted for by any other supposition ; and, also, that had the existing arrangement of the solar system been left to accident, the chances against the occurrence of the present organization would have been as four millions of millions to one. " Coincident with these investigations was the discovery by astronomers of the existence in space, far removed from our system, of an im- The Nebular Hypothesis. 27 mense number of objects which, from their foggy, cloudy appearance have been called nebula : some of vast extent and irregular outline, as that in the sword of Orion, which is visible to the naked eye ; others of shape more defined and regular; and others, again, in which small, bright nuclei, apparently con- densed points, appear here and there over the surface. Ascending higher, as it were, in the scale of progress, we have next clusters of nuclei with nebulous matter around them ; and then what are called ' nebulous stars,' or luminous spherical objects bright in the cen- ter and dull toward the extremities existing, however, in every stage of concentration, from stars with ill-defined centers to stars invested with only a slight burr or haziness. " Upon these facts, mainly, has been built up the so-called Nebular Hypothesis which sup- poses that the various appearances we have described represent the various conditions which suns, systems, and worlds pass through in their progress of formation ; the cloudy neb- ula representing matter in its original chaotic condition ; the defined nebula, the first stage of condensation ; and nucleeatd nebula, a.^d 28 THE MODERN GENESIS. the succession of nucleated stars, the more advanced and final stages ; just as a child, a boy, a youth, a middle-aged and an old man, indicate the successive periods in the life of a human being. But whatever may be the physical condition of the nebula, the main features of 'the theory of Laplace curiously accord with the antecedent condition of our system as deduced from its present peculiari- ties ; and it is accordingly inferred that, in the ' beginning/ our solar system was an immense sphere of nebulous matter, filling all the space now occupied by the system, and extending even to apoint far beyond the limits of the orbit of Neptune, a planet whose average distance from the sun is about three billions of miles. " Assuming the existence of such a nebula in the first instance, the general attractive force resident in all matter would gradually cause its particles to approach each other, and thus, from the outset, the nebulous sphere must have commenced condensing and contracting. ' It is, moreover, a well-known law of physics, that when fluid matter (gaseous or liquid) collects toward or meets in a center, it estab- lishes rotary motion. Every-day illustrations The Nebular Hypothesis. 29 of this law may be seen in the whirlpool or whirlwind, or, to use a more humble illustration, in water sinking through the aperture of a funnel. Thus rotation on an axis would com- mence, at first slow, but become quicker and quicker as the condensation increased.' With the establishment of rotary motion, a tendency in the mass to throw off its outer portions would be generated in consequence of the centrifugal force overpowering the central at- traction ; and it is accordingly supposed that masses of matter were, in fact, from time to time, torn away from the nebulous sphere, which detached portions afterward continued their courses separate from the main mass, but preserving a similar direction in their motion. Such detached masses, abandoned successively at different stages of the condensation, formed themselves into single planets, or, like the great original sphere, into planets with satellites and rings, until, finally, the principal mass con- densed itself into the sun, which still occupies its original position as the center of the system, and as the largest body. " Simultaneously with the commencement of condensation in the nebulous matter, the force 30 THE MODERN GENESIS. heat must have manifested itself, since it is a general law of physics that the condensation or compression of all matter, under all circum- stances, evolves heat ; and as condensation and refrigeration further progressed, by the radia- tion of heat into space, other forces, as chemic- al affinity, cohesion, etc., must have exerted an influence, until at last the constituent mate- rials of our earth and the other planetary bodies passed from a gaseous to a fluid or solid condition, and assumed their present forms and properties." Again, WINCHELL says : " We know enough of the phases of matter, in the different prov- inces of space, to feel certain that they represent progressive stages in the natural evolution of matter as such. Whether seen in nebula, star, sun, planet, or satellite, it is a phase in a com- mon history, the earliest periods of which are as truly a part of the history of our world, as the achievements of Alfred the Great are a part of the history of communities of American birth." He also furnishes us a " tentative exhibit of the successive stages of world matter," and says that " there is little doubt that its general The Nebular Hypothesis. 31 tenor expresses a fact in the aspects of the universe." He divides the entire history into chapters, which he denominates PHASES, and these phases into STAGES. The phases are the NEBULAR PHASE, the STELLAR PHASE, and the PLANETARY PHASE. The NEBULAR PHASE has four successive stages : i. The stage of gaseity ; 2. The stage of nor- mal nebulosity ; 3. The stage of continuous fire- mist ; 4. The stage of discontinuous fire-mist. The first of these stages is supposed to be exemplified by "the faint central portions of the annular nebula ; " the second, by " some of the irresolvable nebula /" the third, by "some of the irresolvable nebula" and some stars; and the fourth, by " certain resolvable nebula" The STELLAR PHASE has nine successive stages : i. The primary nuclear stage; 2. The secondary nuclear stage ; 3. The Sirian stage ; 4. The Arcturian stage ; 5. The solar stage ; 6. The variable stage ; 7. The liquid stage ; 8. The incrustive stage ; 9. The eruptive stage. 32 THE MODERN GENESIS. The first of these stages is supposed to be exemplified by " the planetary mbulce " and the " nebular stars ; " the second, by " certain star clusters and most resolvable nebula;" the third, by white stars ; the fourth, by yellow stars ; the fifth, by our sun ; the sixth, by variable stars ; the seventh, by " some star clusters and resolvable nebula ; " the eighth, by red stars ; and the ninth, by temporary stars. The PLANETARY PHASE has five successive stages : I. The Saturnian stage; 2. The Jovian stage ; 3. The terrestrial stage ; 4. The Martial stage ; 5. The lunar stage. These successive stages are supposed to be exemplified by the present condition of Saturn, , Jupiter, Earth, Mars, and the Moon. The first exhibits the ring condition ; the second the formation of an " atmosphere around the incrusted nucleus," and the production of the lower forms of life ; the third witnesses the " culmination of the organic phase ; " the fourth witnesses the " decline of the organic phase," and the fifth witnesses the " extinction of organization " and " final refrigeration." Laplace, a prince among geometricians, de- The Nebular Hypothesis. 33 clares that he put forth his nebular hypothesis with diffidence. The disciples of Laplace, while carrying the theory beyond the thought of the great master, enunciate it at once with almost dogmatic positiveness and with the richest ornamentation of rhetoric. Nothing can exceed the enthusiasm of Win- chell, unless it be the inconceivably high tem- perature of the original world stuff. Nothing can compare with the grandeur of his periods, unless it be the original grand rotation itself. We shall be pardoned, we trust, if we come to the examination and discussion of this sub- ject without enthusiasm. Should our analysis even seem destitute of warmth ; should we betray any lack of appreciation of red-hot phrases, we still trust that cool heads will consent to accompany us while we take this nebular theory in pieces and weigh it in the scales of real science. Huge as it is, it will, we think, submit to analysis and test. 34 THE MODERN GENESIS. CHAPTER III. CAUSE OF ROTARY MOTION. Condensation by gravity Contraction by cooling Illustra- tration of the process The whirlwind and whirlpool Views of Helmholtz Sterry Hunt Tyndall Herbert Spencer. IT must have been noticed that in the two outlines of the nebular theory which we have quoted there was one point of disagree- ment, and it was an essential point. What was the cause of the original rotation of the cosmical mass ? One class of advocates of the theory answer, " The cooling, and consequent contraction, of the mass. 1 ' Another class an- swer, " The general attractive force resident in all matter" It may not, at first sight, occur to the reader that these two causes could not co-exist. Why not? If such a nebular sphere did once exist, must there not have been a resident attractive force ? Undoubtedly. Cause of Rotary Motion. 35 But such an exertion of this force as would result in trie condensation of the mass, would also have resulted in the evolution of heat. If, then, the cosmical mass was condensed and contracted by the force of gravity, it could not have been contracted by the process of cooling off. HELMHOLTZ supposes the " heat of the sun to be maintained by the slow condensation of its mass ; a diminution by T ^ -$ of its present diameter being sufficient to maintain the pres- ent supply of heat for twenty-one thousand years." Professor WlNCHELL, however, is at issue with this theory of condensation, and consequent evolution, of heat. He remarks that, " We can- not safely assert that every or any nebulous body increases in temperature during any period of its history. It seems more probable that a continuous reduction of temperature is expe- rienced, and that the temperature inherent in the sun at the present time is rather the resid- uum of the primordial heat than the effect of the condensation of his mass.' To our present inquiry it is a matter of in- difference which of these two theories is ac- 36 THE MODERN GENESIS. cepted. The cosmical mass may be conceived of as being condensed by the operation of the resident attractive force, and heated thereby, or it may be conceived of as at an inconceiv- ably high temperature in the beginning, and as gradually dropping its temperature by the radiation of its heat and thus contracting its volume, in either case, are we furnished with an account of the origin of rotary motion ? Rotary motion is the one universal fact in the solar system. Rotary motion, in the solar system, suggested the hypothesis of cosmical evolution. Rotary motion is a prime factor in the theory. " All the marvelous uniform- ities of the solar system are but the progeny of that primitive impulse which originated the grand rotation." To account for the beginning of rotary mo- tion is, therefore, the first duty of the advocate of the nebular theory. We have before us two methods of doing this. One makes the rotary motion the effect of the cooling, and consequent contraction, of the mass. The other makes the rotary motion the effect of the condensation of the mass by the force of gravity. If either of Cause of Rotary Motion. 37 these alleged causes existed, was it adequate to the alleged effect ? If both co-existed and co-operated, were they both, when combined, adequate to the task? Let us 'first examine the theory of gravitative force. The resident attractive force which is in all matter is known to produce the spherical form. If, therefore, we conceive of matter existing in the nebulous condition, and in a mass of ir- regular shape, or in detached, but contiguous, masses, we shall readily conclude that this mass, or these masses, will, by the operation of this force, become one spherical- mass. We can also readily conceive of a spherical mass of cosmical matter, the diameter of which shall exceed that of the orbit of the most distant planet. It may not be amiss, at this point, to look at the magnitude of such a sphere, and con- sider what the condition of the matter of our solar system must have been if thus expanded. In round numbers, the mean diameter of the orbit of Neptune is about six thousand millions of miles. The volume of such a sphere would be 311990 38 THE MODERN GENESIS. 1 1 5,041 ,600,000,000,000,000,000,000,000 cubic miles, or more than three hundred and forty billions' times the present volume of the sun, which is five hundred times the volume of all the planets combined. Professor HELMHOLTZ justly distinguished among physicists says : " If we calculate the density of the mass of our planetary system, according to the above assumption, for the time when it was a nebulous sphere, which reached to the path of the outmost planet, we should find that it would require several cubic miles of such matter to weigh a single grain." This, then, is the condition of the cosmical matter, when, according to the theory which we are now examining, the general attractive force, which is resident in it, commences the work of inaugurating a rotation of the mass on an axis. Can it do it ? The paramount force, or, rather, the result- ant force, exerted by all the atoms of the mass upon any single atom, will be in what direc- tion ? Toward the center. It cannot deviate from the center by so much as a hair's breadth. The force of gravity on all parts of the mass must be exactly centripetal. Cause of Rotary Motion. 39 But can this centripetal tendency of the particles produce rotary motion ? There is nothing in the nature of the force to lead to such a conclusion. On the contrary, all fluid matter possesses a buoyant power ex- actly proportioned to its density. If all the mat\ ter be of uniform density it will be uniformly j buoyant, and, though acted on by gravity, it will remain in a state of rest. But if we supr pose the atoms of different elements having different specific gravity to seek the center and to gain it at the expense of the lighter ele- ments, then there must arise only a process analogous to that of sedimentary deposition, the moter effect of which would be insensible. We might conceive of a central nucleus of liquid or solid matter thus being formed ; but inasmuch as the deposit would be uniform on all sides and exactly central to the mass, (the lines of descent being exactly centripetal,) we cannot perceive how this could inaugurate rotary motion. If the matter be not at a temperature too high to admit of increase by this process of condensation, then, evidently, heat must result. But what force, besides heat, is known that is 40 THE MODERN GENESIS. capable of so attenuating the matter which is known to exist in the solar system as to fill the space required by the nebular theory ? Nay, is it known that heat itself is capable of doing it? But, if the matter be thus attenuated by heat, could its condensation take place at all except by cooling? But, admitting that it could, have we found a cause for rotary motion ? Not yet. There is a hypothetical deposition of the denser elements. It goes on equally from all sides, and as the denser elements go down, the lighter elements are lifted toward the surface. This process, we should suppose, would result in the gradual arrangement of the cosmical mat- ter in concentric strata, in regular order from the most dense at the center to the least dense at the surface. Two forces, allowing that the elements were freely intermixed in the begin- ning, might be supposed to counteract this operation of the resident force of gravity. The force of cohesion, though feeble in its action upon aeriform matter, still performs im- portant offices in the present state of matter. By it we suppose the water of the deep seas to keep up a supply of air sufficient to sustain Cause of Rotary Motion. 41 the life that exists in the waters ; and by it the air is enabled to hold aqueous vapors in suspension. By it the atmosphere itself may be said to keep the due proportions of its gas- eous constituents always present, for atmos- pheric air is not a chemical compound, but a mixture. So, also, we may conceive of this cohesive attraction as interfering, in some degree, with the process of stratification in the aeriform cosmical mass. The chemical force affinity would at certain temperatures entire- ly arrest the supposed process of stratification ; but it would only arrest it to substitute one of another kind in its place, namely, a stratifica- tion of compound substances. There seem to be two opposite conditions of the original matter assumed by the two classes of nebular theorists. One represents the mat- ter as inconceivably hot. The other represents the matter as heated by the operation of the attractive force. Assume the truth of the latter representa- tion ; then, so soon as the matter reaches a temperature at which affinity can act, there must be general chemical combination. As- sume the truth of the former representation ; 42 THE MODERN GENESIS. then, so soon as the temperature gets down low enough, there must be general chemical combination. In either case there would re- sult condensation by combination. But such condensation could only be of the particles in contact ; and we may conceive of the deposition of compounds almost infinites- imally minute, through substances in which affinity was not yet brought into play. And still in none of the operations, which we have conceived of as possible, is there any thing, so far as we can see, to produce a rotary motion of the mass. But if we assume that the original matter existed at an incon- ceivably high temperature, then we must con- sider the elements as free. Dr. HUNT remarks : " Of the chemical rela- tions of such intensely heated matter, modern chemistry has made known to us some curious facts, which help to throw light on the con- stitution and luminosity of the sun. Heat, under ordinary conditions, is favorable to chemical combination, but a higher tempera- ture reverses all affinities. Thus the so-called noble metals, gold, silver, mercury, etc., unite with oxygen and other metals ; but these com- Cause of Rotary Motion. 43 pounds are decomposed by heat, and the pure metals are regenerated. " A similar reaction was many years since shown by Mr. Grove with regard to water, whose elements oxygen and hydrogen when mingled and kindled by a flame, or by the electric spark, unite to form water, which how- ever, at a much higher temperature, is again resolved into its component gases. The re- cent researches of Henry Sainte Claire Deville and others go far to show that this breaking up of compounds, or dissociation of elements by intense heat, is a principle of universal ap- plication." Our cosmical matter, then, while existing at an inconceivably high temperature, is free from the action of chemical affinity. There is but a single force operating to pro- duce any great change in its structure, and that single force is gravity. And we know that, to this force, all matter, in all conditions, is subject. There is no force contemplated as acting on the cosmical mass from beyond itself to give it a rotary motion. The conditions of the nebu- lar hypothesis forbid this. This cosmical his- tory is a history of evolutions. Causation is all within. 44 THE MODERN GENESIS. The rotary motion had its origin in some primitive impulse, evolved out of the world matter itself, or resident in it. Tyndall refers all the motions of the universe to the gravita- tive attraction, saying, "The potential en- ergy of gravitation was the original form of all the energy in the universe." If TYNDALL does not know who does ? Certainly no affir- mation could be more positive. HELMHOLTZ also refers the condensation of the original matter to attraction ; but he does not refer the beginning of rotary motion to the same force. He says we must assume its existence. These are his words : " The general attractive force of all matter must, however, impel these mass- es to approach each other, and to condense, so that the nebulous sphere becomes incessantly smaller, by which, according to mechanical laws, a motion of rotation originally slow, and the existence of which must be assumed, would gradually become quicker and quicker." We are persuaded that HELMHOLTZ is right the existence of an original rotation must be assumed, and if assumed, then we confess that it cannot be accounted for. But it is alleged that, " It is a well-known Cause of Rotary Motion. 45 fact that when fluid matter (gaseous or liquid) collects toward or meets in a center, it estab- lishes rotary motion," and the whirlwind and whirlpool are cited as illustrations of this law. But we see no analogy not the least between the conditions which produce either of these phenomena, and the supposed conditions of the cosmical mass, whose rotation is to be account- ed for. The whirlpool exhibits the following inci- dents : i . An escape of water through an orifice. 2. A flow of the water in the mass toward the orifice seeking an equilibrium. 3. The down- ward current of escape, and the reaction of the centripetal currents after impact, give rise to a rotary motion, which continues only so long as the equilibrium is unrestored. But in the nebular mass we have found a perfect equilibrium already existing. The whole mass is supposed to be aeriform and spherical. All is balanced about the center of gravity. And the center of gravity is not a vacuum into which the cosmical matter rushes, meeting, reacting, and moving off through some outlet opened for it. If we could conceive of an 46 THE MODERN GENESIS. axial outlet, and an equatorial centripetal flow, we might thus imagine the existence of a con- dition of things analogous to those in the whirlpool. But we cannot conceive of such an outlet, for the attractions are all so adjusted that every part of the sphere equally distant from, is equally drawn toward the center. There is no axis, for there is no rotation. In the whirlpool there is an escape of the water downward, producing a vortex. In the whirlwind there is an escape of the air up- ward, producing a vortex. Did the force of gravity ever yet produce a vortex by drawing matter into its own center ? In the whirlpool and whirlwind, were there no such escape of the central matter, there could be no centripetal flow. Whenever the oiifice is stopped the centripetal flow ceases and the whirlpool ends. It is by the escaping current that the cen- tripetal currents are modified as they approach the central point, so that they flow not to it, but around it. Conceive now, not of a sudden rush of mat- ter to a central void ; not of the violent impact Cause of Rotary Motion. 47 of elements seeking an avenue of escape, and moving forward after impact to the place of escape by a modified motion ; but of a mass of matter in equilibrium, from every point of which there is a gravitation toward the center. That matter which is at the center is at rest. That which is near the center is at rest. All is at rest. But the specific gravity of the elements being different, the elements also being dis- sociated, and therefore free to obey the gravi- tative force, we may conceive of them as part- ing company, and the denser elements descend- ing slowly toward the center. But if such a movement be imagined, it must be supposed to begin simultaneously every-where and to go on equally on all sides. Then the elements of highest specific gravity which are nearest the center will reach it first and rest. Two motions there would be, the centripetal motion of the denser atoms, and the radial motion of the lighter atoms. The gravitation of all toward the center simply increases the density of the central mat- ter, and gives it greater buoyant power so long as it remains fluid. 48 THE MODERN GENESIS. But we do not see any thing in the supposed conditions to produce rotary motion in the mass. We are obliged, then, to declare the problem of rotary motion unsolved by that form of the nebular theory which refers it to the general attractive force. But what would be the effect of that evolu- tion of heat which must result from condensa- tion ? Perhaps it would cause an expansion of the volume. But what then ? The direc- tion of the condensing force is centripetal. The expansion must be radial. But this could not originate rotary motion. We know of no law or principle of matter that explains the origin of rotary motion. Let us now turn to the consideration of the theory enunciated by WlNCHELL, which al- leges that the rotary motion was caused by the cooling, and consequent contracting, of the original cosmical sphere. It is to be regretted that the advocates of this theory have not entered more largely into the discussion of it. No one condescends to give us the rationale of it. How does the process of cooling and contracting the mass impart to it rotary motion ? Cause of Rotary Motion. 49 The cosmical mass is, according to the theory, at an inconceivably high temperature. The phenomenon of combustion, being a chem- ical one, is impossible, and the heat of the mass is to be conceived of as inherent, and we do not look for its cause any more than we look for the cause of the cosmical matter it- self. Its presence in the matter is assumed. But, as the resident attractive force would act at the very beginning of its existence, (which must have been at the beginning of the exist- ence of the matter itself,) so also the heat, which was likewise in the matter from the be- ginning, was an active force, and its law was, as it is now, radiation. Modern science teaches that heat is a form of motion. There is molecular motion, which is heat in the mass. There is an interatomic and inter-stellar ether, whose undulatory mo- tions are radiant heat. We are, then, to conceive of the cosmical matter in a state of high heat, that is, pervaded throughout with the highest thermal activity, which is imparted to the enveloping ether, and thus radiated into space, its radiations proceeding in right lines, the same as light. 4 50 THE MODERN GENESIS. The radiation is from the entire surface. The thermal activity is equal over the entire surface. The ethereal envelope is homoge- neous every-where, and therefore the cooling must go on equally over every part of the sur- face. Moreover, if by convection or otherwise the interior heat be so brought to the surface as to maintain nearly the same temperature throughout the mass, still the cooling will take place equally in all directions from the center. The cooling of the surface would contract the surface, and the cooling of the mass would contract the mass. But the contraction would be in the direction of the center. It would be equivalent to a subsidence of the surface. Could this insensible universal depression of the surface produce a rotary motion of the mass? We see not how it could. But it is gravely urged that we have an il- lustration and proof of this theory, also, in the whirlwind and whirlpool ; and we are obliged to re-examine those phenomena, which, if not analogous to the supposed action of the cos- mical matter under the influence of gravity, are, we think, no more analogous to the behav- Cause of Rotary Motion. 51 ior of the cosmical matter under the conditions we are now considering. The whirlpool, on a small scale, is a famil- iar object. We observe the displacement of a central body of water, the rush of the exter- nal water to the space thus made vacant, and the impact of the currents thus formed. The momentum of the innumerable cen- tripetal currents at the moment of impact must entirely neutralize those currents, or cause a rebound in the lines in which they ap- proached the center, or they must change their direction. The escaping current determines the result by forming a column of transverse motion. Without arresting the centripetal currents, it changes their direction downward, so that there arises a resultant motion, which is spiral. Were there no centripetal momentum, or i were the orifice of escape so large as to allow of no reactions, there could be no whirlpool. But it should not be forgotten that the rotary motion begins at the center, or the place of dis- charge, that it tends to produce a vortex, and K f . it enlarges its circles outivardly. t does not begin on the exterior, and com- 52 THE MODERN GENESIS. municate its motion inwardly till the whole mass is in motion. But is not this what the theory of cooling and contracting assumes? The assumption is contrary to the phenomena cited to support it. But it may be asked, " How did the rotary motion originate ? There is rotary motion. How do you account for it?" We do not account for it. We have no physical theory on the subject. Mr. Herbert Spencer exhibits the rationale of axial rotation as follows : " If we assume the first stage in nebular condensation to be the precipitation into floculi of denser matter previously diffused through a rarer medium, (a supposition both physically justified and in har- mony with certain astronomical observations,) we shall find that nebular motion is interpret- able in pursuance of the above general laws. Each portion of such vapor-like matter must begin to move toward the common center of gravity. The tractive forces, which would of themselves carry it in a straight line to the center of gravity, are opposed by the resistant forces of the medium through which it is drawn. Cause of Rotary Motion. 53 " The direction of movement must be the re- sultant of these a resultant which, in con- sequence of the unsymmetrical form of the floculus, must be a curve directed not to the center of gravity but toward one side of it. And it may be readily shown, that, in an ag- gregation of such floculi severally thus moving, there must, by composition of forces, eventually result a rotation of the whole nebula in one direction." But does not Mr. Spencer in this instance, and in other instances in which he substantially repeats these thoughts, totally ignore one of the established principles of natural philosophy, namely, the equality of action and reaction? Supposing it to be true that the descending floculi are unsymmetrical, and that their un- symmetrical forms are all exactly alike, and that their corresponding parts were set in the directions must favorable for giving to them severally that exact direction which would re- sult in their reaching, not the center of gravity, but a line which would be the axis of their combined motion, would it follow that the whole nebula would take such an axial motion ? What becomes of that resisting medium 54 THE MODERN GENESIS. through which the floculi descend ? How does it cease to be a resisting medium ? The de- gree of force with which it resists is supposed to be sufficient to divert the floculi from their perpendicular descent. But the resisting medi- um can exert no more resistant force than the descending floculi exert of direct force. Then the medium must have a motion imparted to it. And its motion must be exactly opposite to that of the floculi. If the floculi descend in curves, the medium will ascend in opposite curves. No axial rotation of the whole mass can arise here until there be a suspension of the law that action and reaction are equal. If, then, " We assume the first stage in nebular condensation," we are not able to interpret the axial motions of worlds by that assump- tion. We are obliged also to assume that the nebular mass had an original rotary mo- tion, for the beginning of which modern science is unable to account, just as it is unable to ac- Vcount for the nebular matter itself. Ring Formations. 55 CHAPTER IV. RING FORMATIONS. Rings of Saturn Plateau's experiment The centrifugal force Discussion of principles The sphere The spheroid Calculations of oblateness Could rings be detached ? A SSUMING the existence of the nebulous /" cosmical sphere ; assuming that it has in some way received a rotary motion ; assuming that it cooled and contracted, and that its rotary motion was accelerated ; we now come to the examination of the next chapter of the cosmical history. What has the rotary motion accomplished ? The Nebular Hypothesis tells us what : " A peripheral ring was detached which be- came a planet. The same process continued and other rings were detached, which became the other planets in due succession. Similarly, the planetary masses detached rings which be- came their satellites. Thus all the marvelous uniformities of the solar system are but the progeny of that primitive impulse which orig- 56 THE MODERN GENESIS. inated the grand rotation." Wine he II. "A peripheral ring " is certainly a pleasant eupho- ny. A " primitive impulse, which originated the grand rotation," is a truly sonorous phrase. But it is not unreasonable to ask, Have we any warrant in known principles and facts to justify the conception which these terms ex- press ? The advocates of the Nebular Hypothesis re- fer us to the revelations of the telescope. There is, it is alleged, an instance of the ring- condition to be seen in the heavens. Saturn has rings. It is conjectured that Neptune has rings. " In Saturn we discover a planet which, if we may trust the determinations, is even lighter than water. No surface features of the body are discernible, and it seems, like Jupiter, to remain enveloped in a mass of belted clouds. Its most striking phenomena are its eight sat- ellites and its grand system of rings. " The first thought suggested by the latter is their demonstration of the truth of the nebular theory of planetary origin. Here we have, as a fact, a perpetual instance of the ring condition a demonstration even more convincing than the laboratory experiment of Plateau. Is this Ring Formations. 57 planet in a more primitive condition than Jupiter, at once the younger and the larger body? " An affirmative answer is indicated both by the rings and the low specific gravity ; and the intensity of its light, making allowance for greater distance and inferior bulk, is almost equal to that of Jupiter. " But the substance of the rings is not aeriform, as we suppose the normal ring-condition to be. It is neither solid nor fluid, as Professor Pierce has demonstrated ; but, according to a sugges- tion of Proctor, may be in a granular state each constituent grain (so to speak) answering to a miniature moon, and the whole assem- blage, millions in number, disposing them- selves, according to the varying influences, in two, three, or more annuli." Wine/tell. This seems to us a singular medley of strangely contradictory statements. First. In Saturn we have, "as a fact, a perpetual in- stance of the ring-condition ; " but afterward there is no ring-condition at all, but millions of miniature moons. Secondly. This "per- petual instance of the ring-condition " (which, after all, is not an instance of the ring con- 58 THE MODERN GENESIS. dition) is a " demonstration of the truth of the nebular theory of planetary origin ; " and yet, though according to that theory the ring-con- dition is an aeriform condition, this system of miniature moons is not a system of aeriform bodies. Instead, then, of being a demonstra- tion of the truth of the nebular theory of planetary origin, it is suggestive of the incom- patibility of that theory with the observed facts of planetary existence. The non-con- tinuity of the apparent rings, which has been suggested by Proctor, is now generally received as a truth by astronomers, who are able only on this supposition to account for their ob- served motions. Nor is it difficult to understand how less than millions of small moons, revolving around the body of Saturn in orbits whose planes lie edgewise, or slightly inclined to our line of vision, and completing their revolution in ten hours and thirty-two minutes, should produce the illusion of a ring-condition. A few hun- dred small moons flying at the rate of 48,000 miles an hour would, we think, be sufficient to produce the illusion. Yet it is no more in- credible that thousands of moons should be Ring Formations. 59 found revolving around a planet, than that thousands of asteroids should be revolving around the sun inside the orbit of Jupiter. The laboratory experiment of Plateau is also referred to. This experiment has been the ground of a vast amount of faith in the nebular theory. Winchell says, it is convinc- ing ; but the ring-condition of Saturn is dem- onstration, more convincing. Our readers will, therefore, give to Plateau's celebrated experi- ment the consideration it deserves. Certainly, we must admit that the first an- nouncement of the experiment produced a great sensation in scientific circles. 'M. Plateau, a Belgian physicist, succeeded in producing rings around a revolving body. If any one wishes to try the experiment let him take a glass vessel and fill it half full of spirits of wine. Now drop into it a small quan- tity of olive oil. The oil, being of greater specific gravity than the spirits, will sink. Now add water until the specific gravity of the mixture is just sufficient to float the oil near the surface. The oil will have assumed the globular form. Now, through the globule of oil pass a wire, which has first been mechan- 60 THE MODERN GENESIS. ically adjusted so that it can be rapidly re- volved. Revolve it, at first slowly, then gradu- ally increase the rapidity of the rotation. The oil globe will revolve around the wire as an axis. With the increase of the velocity of ro- tation the globe flattens, and finally detaches a ring, which breaks up into globules, and they revolve around the central portion. This is the experiment which is only less convincing as to the truth of the nebular theory of plane- tary origin than the demonstration afforded by the ring-condition of Saturn ; a condition which, it is confessed, does not exist at all. Let us now examine this experiment. What are the elements of it which are analogous to the details of the nebular theory, so that this is worthy to convince an intelligent inquirer of the truth of that ? 1. The substance chosen for the experiment is one which has a high degree of coherency compared with its specific gravity. The cos- mical mass is supposed to have been aeriform, and of extreme tenuity, in which case its co- herency must have been almost zero. 2. The attractions of the particles of the oil for each other are so feeble that they are only Ring Formations. 61 able to produce the spherical arrangement when inclosed in a medium of the same specific gravity, and, when revolved, they the more readily obey the centrifugal force, and the whole mass breaks up into fragments ; but the masses which are supposed to have been de- tached from the cosmical sphere were minute portions compared to the whole mass which re- mained unbroken. 3. The experimental substance revolves by the application of external force ; but the cos- mical sphere is supposed to have revolved by a force originating within itself. 4. The experimental substance revolved in a medium of its own specific gravity. But the cosmical sphere is supposed to have revolved in void space. 5. The experimental substance is subject to the frictional resistance of the medium in which it revolves, which resistance must in- crease as the revolving substance flattens and extends. But the cosmical sphere is not supposed to have been thus resisted by any external matter. 6. The rotation of the oil globule imparts to the medium in which it floats a rotary 62 THE MODERN GENESIS. motion. The centrifugal force having over- come the coherency of the oil, it breaks up into minuter globules, and these continue to revolve for a time, being carried around by the circular current of the medium itself. But the de- tached masses of nebulous matter are not sup- posed to have floated in any medium whose motion directed theirs. Are the physical conditions in the two cases the same or analogous ? Are the motor forces the same or analogous ? Are the results the same or analogous ? To each of these questions we think the un- biased mind will answer no. The fact that the globule of oil is flattened and enlarged and broken up into minuter glob- ules, and revolved around the center, is the only feature of the experiment which may be said to be analogous to the assumptions of the nebular theory ; and here the analogy is only phenomenal. Could M. Plateau devise some means by which a globe of air could be revolved in a void, and air rings could be detached by the centrifugal force alone, and these rings could be gathered into smaller air globes and Ring Formations. 63 kept revolving around the parent mass in the void, he would thus exhibit something more nearly analogous to the hypothetical cosmical evolution. Having thus glanced at the supposed illus- trations and demonstrations of the nebular theory, afforded on the grand scale by the phenomenal ring-condition of Saturn, and on the minute scale by a few drops of oil, we now wish to examine the theory on its own prem- ises, and bring it to the test of philosophical and mathematical principles. For this purpose we assume the existence of the spherical cosmical mass in space unirPv fluenced by any force outside of itself, and we \ assume for this spherical mass an axial rotation, which by the contraction of the mass must / have been accelerated. So much we assume/ with the advocates of the theory. Now we know that rotary motion produces what is known as the centrifugal force. But the centrifugal force is nothing more or less than the tendency of a body moving in a circle to go on exactly in the direction in which it is moving at any given point in the circle, and that direction is always a tangent of the circle. 64 THE MODERN GENESIS. The centrifugal force is the projectile force of circular motion. With the increase of the rate of rotation there is an increase of this projectile force. If we double the rate of motion we quadruple the force of the same mass. But whatever may be the rate of the rotation, a projectile can never be thrown farther out by the cen- trifugal force than the tangent of the circle. Conceive now of every point on the circle as being thus projected along the tangent line, and the result must be an expansion of the cir- cle itself to an extent determined by the rate But the rate of rotation being the same in circles of different diameters, that is, the com- plete revolution being accomplished in the same time, the larger the circle the greater the centrifugal force, because the velocity must be greater. If, then, a sphere be rotating on its axis, its greatest circle of rotation will be its equator ; and every parallel of latitude will be a smaller circle of rotation, until at the pole it will be, so to speak, the rotation of a point. Therefore, at the poles there can be no centrifugal force, Ring Formations. 65 while at every successive point, in passing from the pole to the equator, there will be an in- creasing centrifugal force, and at the equator the greatest of all. If, then, the substance of the revolving sphere be of a yielding nature, the effect of the centrifugal force must be to elevate the equatorial region, and, correspond- ingly, to depress the polar region. We have an example of the effect of the centrifugal force on the shape of a revolving sphere in the earth itself. Here the equatorial region has been elevated and the polar region depressed until there is a difference of twenty- six and a half miles between the polar diame- ter and the equatorial diameter. By the centrifugal force the earth is rendered an oblate spheroid. To indicate the rate of the rotary motion in different bodies we notice the time of the rota- tion, and what part of a complete rotation is performed in a certain specified time. Usually one hour is the specified unit of time. Then, inasmuch as the earth revolves on its axis once in twenty-four hours, it must perform one twenty-fourth of a revolution in one hour. But -^ of a rotation is jV of 360 66 THE MODERN GENESIS. degrees, or fifteen degrees ; and, therefore, we say that the rate of the earth's axial rotation is fifteen degrees an hour, just as we would say of a railroad train that it moves at the rate of . fifteen miles an hour. / Miles are a definite linear measure. Degrees / are a definite circular measure ; but it must be remembered that the rate is the same for all \ parallel circles of the same sphere, be they \great or small. The earth's axial rotation at the rate of fifteen degrees an hour produces a centrifugal force sufficient to make the equatorial diameter twenty-six and a half miles greater than the polar diameter ; making the oblateness of the earth ^g of its mean diameter. The planet Jupiter affords a still more strik- ing example of the effect of the centrifugal force in giving oblateness to a spheroid. The axial rotation of Jupiter is accomplished in less than ten hours. The rate of the rotation is, therefore, thirty- six degrees per hour, which is two and two fifths times that of the earth. Moreover, the density of Jupiter is only about one fourth that of the earth, and hence, by estimation, the Ring Formations. 6/ oblateness of Jupiter has been found to be about T V of his mean diameter, but by obser- vation it is T ' T . Saturn is a still more remarkable example, his oblateness being about T V of his diameter. The axial rotation is at a lower rate than that of Jupiter, but its density is also only about half as great. Great, however, as is the oblate- ness of Saturn, a person standing on its equator would have around him an expanse the curv- ature of whose surface would be much less than that of the earth's equatorial region. What would be the effect were the axial rotation of Jupiter to be accelerated to twice its present rate ? Then its rate would be seventy-two degrees an hour, or 4.8 times as great as that of the earth. The centrifugal force of this high rate of rotation would be about twenty-three times that of the earth's rotation if the two bodies were of equal density; but as Jupiter's density is only one fourth that of the earth, the effect of centrifugal force will be four times as great, and will be expressed by ^W of the diameter ; for 4.8 2 X4Xyfa=-ffo. The oblateness of Jupi- ter would then be one third of his mean 68 THE MODERN GENESIS. diameter. And yet Jupiter would be but a spheroid. So far as we can see, in the light of known physical principles, the Continuity of the planet- ary substance would remain unbroken. The polar diameter would still be fifty-six thousand miles, and its meridional curvature at the equa- tor would be far less than that of the earth at the present time. We can see no promise here of ring for- mations. Apply the same principles to the supposed original cosmical mass, a sphere more than six thousand millions of miles in diameter. Im- agine it in motion on an axis. Imagine it ex- tending out equatorially and settling down at the poles ; to what extent can this process be carried, and what will result ? Is the rotary motion, however much it may be accelerated, adequate to the production of a peripheral ring ? We must not forget that this cosmical sphere is revolving in a void. There is no external matter whose friction or attraction can modify the result. If it be alleged that there is other matter in the universe whose attraction must Ring Formations. 69 have reached the cosmical sphere and affected it, we reply that the nebular hypothesis does not take such external attractions into ac- count. It professes to find all its world- forming forces within the mass, and the whole planetary history is one of evolution. The only force accredited with the work of producing a peripheral ring is the centrifugal force. The ring is only alleged as an incident in the process of planetary genesis by the grand rotation, and the ring is alleged only because the centrifugal force is known to en- large the equatorial measure of a sphere. The force of gravity would arrange the cos- mical matter into a true sphere. The centrifu- gal force would change it into a spheroid. But the equation of these two forces will always be such that there cannot be such a thing as the casting off of any portion of the mass. We could conceive of the entire coP\ mical matter as assuming the form of a ring, \ but we know of no fact in nature, and no J ' principle, that warrants the idea that a could be detached. But we may readily conceive that another effect, which also is claimed by the advocates 70 THE MODERN GENESIS. of the nebular theory, would follow. The more elongated the spheroid became the more extensive would be the surface exposed to the outlying frigid space, and the more rapidly the mass must cool off and contract. If we suppose the equatorial region to be thinnest it must contract most rapidly, and by its contraction diminish the oblateness of the spheroid. The advocates of the theory find, in this equatorial contraction, the means of accelerat- ing the rotary motion. And yet none of them have appeared to be conscious that an elongation of the equatorial diameter must, on the same rational grounds, diminish the rate of the rotary motion. But if the contraction of the circle of rotation accelerates the velocity, the en- largement of the circle of rotation must dimin- ish the velocity. Here, then, in the nebular theory, we have dilation and contraction hypothetically incident to the cosmical history, incidents alleged by the theory, and one of them quoted to show how the grand rotation was " inevitably ac- celerated; " the other quoted only to show how the ring-condition could arise, quite uncon- Ring Formations. 71 scious of the truth that, if contraction acceler- ates, dilation must retard, the rotary motion. Between them must not the rotary motion^) remain constant ? But, in any event, we do not find that the centrifugal force could detach a ring from the equatorial regions of the mass. The centrifu- gal force acting proportionately at all latitudes, the thinning out at the equator cannot be such as would be required to meet the ex- igencies of the theory. The whole figure must be proportionately molded by the forces which are at work. As the equator arises the pole must be de- pressed, and every point between them must be affected. Not to the extent to which the equatorial matter is projected outward by the centrifugal force, but to an extent proportion- ate to the diameters of the circles, will the matter under every parallel of latitude be pro- jected forward by the centrifugal force in the planes of those circles, while the gravity of all will tend toward the center of the mass. Thus, while the centrifugal force would flat- ten the spheroid, the gravity of the mass binds it, as nearly as possible, to the spherical form. 72 THE MODERN GENESIS. Gravitation assures the continuity of the mass. In Plateau's experiment the only binding force was the cohesive attractions of the molecules of oil. Cohesive attraction once overcome, either by the centrifugal force or by abrasion by the medium in which the matter revolved, the oil globules could only separate ; and the rotation of the medium continuing, the globules could only continue on, borne by the circular currents around the axis of rota- rtlon. But gravitation is never overcome. It Ltontinues to act on the mass and on each atom of the mass through all distances and in all situations, and so it binds the mass together. We can, as before stated, conceive of a rota- tion which would throw all the matter of a sphere out from the center, so that the sphere /would become a ring ; but the ring would be / cylindrical, and there is nothing in the single Mact of rotation to shatter such a ring into fragments so long as its constituent materials remain plastic. But the formation of such a ring is not in the Nebular Hypothesis. Moreover, the supposition that such a ring could be produced by such a rotary motion as would arise from inevitable acceleration, is op- Ring Formations. 73 posed by the postulate that it is contraction \ which accelerates the rotary motion, for by / our supposition there is not contraction but / diametrical enlargement of the revolving mass: The nebular theory, however, does not con- template the formation of such a ring. The ring hypothetical is a peripheral ring. We are to conceive of the cosmical spheroid as letting go of its equatorial protuberance, so that it be- came detached, lifted away from the body of the spheroid, and left to revolve on its own ac- count. But the advocates of the theory do not explain by what force the matter which is thus separated is lifted away, while the ad- jacent matter is not lifted away. No repul- sions enter into this theory. The " grand rotation " accounts for every- thing. But we submit that, according to the theory, the grand rotation involves the whole mass of the cosmical matter. There is a rotation of the earth, and it ele- vates the equatorial region, but it does not lift it away from the earth, and it never did. That the " moon is an outlying fragment of the earth's former equator," may be an allow- 74 THE MODERN GENESIS. able figure of speech, but it is a bald assump- tion in physics. The truth is, that just so soon as there is an elevation of the equatorial surface, the force of gravity brings in supporting matter from the latitudes, and the continuity is maintained. And it must be so always, unless there be some adverse principle of physics of which we are not yet informed. Actual Velocities. 75 CHAPTER V. ACTUAL VELOCITIES. Actual velocities The Sun's motions Planetary motion " The original grand rotation." HAVING considered the possible effects of a supposed accelerated velocity in the rotation of the cosmical mass, we now come to the consideration of actual velocities. Taking a survey of the solar system, we find that rotary motion exists in two forms, which we denominate axial and orbital. The axial rotation is the rotation of a body on its own axis. Such a rotation is found in the sun, in most of the planets, and in their satellites. Uranus and Neptune are not positively known to revolve on their axes, but the analogies of the system justify the belief that they do. Orbital motion is the motion which one body has while revolving around another body. The satellites revolve in orbits around the planets of which they are the satellites. The 76 THE MODERN GENESIS. planets revolve, in orbits, around the sun, carrying their satellites with them. The asteroids are small planets which re- volve also around the sun. Besides these examples of rotary motion, that granular system, which was long regarded as a system of rings, revolves around the planet Saturn in nearly circular orbits. The comets, also, because they revolve around the sun, are to be considered as belonging to the solar system ; yet, because of the great eccen- tricity of their orbits and the great length of their periodic times, are regarded as strangers and foreigners. Still the comets must be accounted for as members of the cosmical family. The sun itself is moving through the heav- ens in the direction of the constellation Her- cules, according to Herschell. Herschell an- nounced his discovery in 1783, fixing the point in the heavens toward which the sun is moving- at two hundred and fifty-seven degrees in right ascension and twenty-five degrees north- ern declination. MAEDLER has announced, as the result of his observations and estimates, that the center Actual Velocities. 77 of the sun's orbit is in the neighborhood of Alcyone. Although no one, so far as we know, has computed all the elements thereof, there is little reason to doubt that the sun re- volves in an orbit. And this fact carries our thought to another beginning. Cosmical his- tory is but meager if it leave out the origin of the solar cosmical mass itself. If satellites are the progeny of the rotation of planetary mass- es if planets are the progeny of the rotation of that cosmical mass of which the sun is the residuum then, whence this vast cosmical mass itself, which originally embraced not only the sun, but also all the planets and all the satellites ? Was it also once a peripheral ring ? If so, of what? And has the sun an orbital motion through space which is the progeny of a still older and grander rotation ? But let us return. We are ascending heights, whence, looking down, thought grows dizzy. If the Nebular Hypothesis be true, we ought to be able to find some trace of the " original grand rotation." Somewhere, among all these revolving bodies, there must be at least a clew to it. The theory is, that the original cosmical 78 THE MODERN GENESIS. sphere in some way obtained an axial rotation. This axial rotation was accelerated to such a degree that it cast off from the original a planetary mass, which continued to revolve around the parent body. Though the motion of the original mass was axial, yet the con- tinued motion of the planetary mass was or- bital, and it also acquired an axial motion. The original mass is supposed to have grad- ually contracted ; its motion was thereby accel- erated, and it threw off another planetary mass. The first planetary mass also contract- ed, its axial motion was accelerated, and it threw off a mass which became a satellite. And this process continued until all the planets were thrown off from the original, and all the satellites from their planets. Such is the theory, and in the light of it we again remark, we surely ought to be able to find a clew to the original grand rotation. We suppose, in fact, that the orbital velocity of each of the planets must indicate what the axial velocity of the cosmical mass was at the time that each planetary mass was projected into space. No one will, we think, claim that the veloc- Actual Velocities. 79 ity of the planetary mass in its orbit could be greater than the axial velocity which projected it into space. Allowing that it received a certain initial velocity at the moment of detachment, it would maintain that velocity only until the attraction of the parent mass should overcome it, and it would then commence a return to- ward its source. After commencing its return its velocity must be accelerated until its centrif- ugal force should again preponderate and carry it away into remoter space again. But the mean of its velocities would be its original velocity, and its orbital period would be the time occupied by the parent mass in making one axial revolu- tion at the date when the planetary mass was detached. The next question which arises is this: Is the orbital period of a planet now what it was when the planetary mass was detached ? We know of no force but gravity to affect planetary motion ; and we have seen what the result would be when there was but a single planetary mass and the original cosmical mass within the limits of the solar system. When other planetary masses were detached, 8o THE MODERN GENESIS. the relative positions of these masses would temporarily affect the result. But there could never arise such a collocation of the spheres as would destroy the equilibrium of the system as a whole. Suppose, then, that the orbital motion of one planetary mass be at one time so retarded by the attraction of another plan- etary mass as to lengthen its periodic time, at another time the effect of the attraction of the same planetary mass will be to shorten its periodic time, so that the sum of all its effects shall be zero. Then the periodic times may be said to be the same from age to age. The mathematics of astronomy are exceed- ingly exact. The planetary periods are com- puted to seconds of time. And so reliable are these computations, that on the credit of them individuals, learned societies, and even na- tions, incur vast expense and fit out expe- ditions for the purpose of observing certain astronomical phenomena which have been predicted for years. They are predicted math- ematically. The very second when the phe- nomenon shall be first visible, and the spot on the earth's surface from which, if at- mospheric conditions are favorable, it can be Actual Velocities. 81 most advantageously observed, are noted and announced. We write in December, 1873, and yet we know that on the 8th of December, 1874, a transit of Venus will occur. But we know, also, that if we would see it we must have a station somewhere in the remote east ; for only to Asia, Australia, the Sandwich Islands, etc., will it be ' visible. Already the world is astir with preparations to observe that transit. The world has faith in astronomical calcula- tions. It is entirely within the range of such computations to declare the exact moment of the beginning of an eclipse of the sun a thou- sand years hence, and to describe its character, as partial, total, or annular, and to announce to what portions of the earth it will be visible. In like manner astronomers foretell the time of a conjunction of any two of the planets, or of any planet with the sun, or the occultation of planet or fixed star. True, all this would be possible were the orbital periods variable quantities, provided the increment of variation were known. But so far as we know there is no permanent change in the orbital periods. 82 THE MODERN GENESIS. It is true that we do not find uniform or- bital motion. The orbits are all more or less elliptical, and the planets move from their aphelion to their perihelion with accelerated velocity, and from their perihelion to their aphelion with retarded velocity. But while the motion is thus variable, the mean of their motions for a thousand years is a constant quantity. The axial periods, or planetary days, are unchanging. Here we find what we do not find in the orbital motion, absolutely unvary- ing rate of motion. Of orbital motion we speak of the perihelion velocity, the aphelion velocity, and the mean velocity. But when we speak of the axial rotation of a planet we never speak of different velocities. The rate of rotation is constant unvarying. From day to day, from year to year, from age to age, it changes not. It is the one only uniform motion of which we know any thing. What the axial rotation of the earth was at the morning of time, that it is now. " The earth has not varied in its revolution," says Steele, " rta of a second in 2,000 years." Then it Aftual Velocities. 83 does not vary a second in two hundred thou- sand years. Laplace estimated the varia- tion at z%~5 f a second in 2,000 years, which would be at the rate of one second in 600,000 years. Such being the constant character of plan- etary periods, we are justified in the declaration that the present orbital period of each planet must indicate what the axial period of the cosmical mass was at the time the planetary mass was detached. And if this conclusion is justified, then the axial period of the " original grand rotation " was exactly what the orbital period of Neptune now is. And, indeed, we understand the advocates of the nebular theory to affirm substantially the same thing. They reason from the present motions of the solar system. The planets now revolve on their axes ; the sun now revolves on its axis ; the planets and their satellites now revolve in orbits, the planetary orbits are now nearly circular, and they are now nearly in one plane, etc. These are facts which are now ob- servable in the mechanism and movements of the planetary system, and they are supposed to point to a condition of the planetary matter 84 THE MODERN GENESIS. and to movements therein millions of ages ago. In maintaining, therefore, the postulate that the axial period of the- original cosmical mass was what the orbital period of Neptune ts, we think we are supported by the reasoning of the nebular theorists themselves. Now we propose to examine the orbital period of Neptune with the view of ascertain- ing what was the original grand rotation. When we have found it we will examine it for the purpose of determining the question of its adequacy to produce a peripheral ring, supposing the production of such a ring to be possible under any circumstances. The sidereal period of Neptune is 60,127 days or 1,443,048 hours. The rate of the rota- tion, then, is, .00025 of a degree (twenty-five, one hundred thousandths of one degree) per hour, or about T \ of a second per hour. The rate of the earth's rotation is fifteen degrees an hour, and at this rate it produces an oblate- ness of only 2%g. But this rate is sixty thou- sand times as great as that of the supposed cosmical mass,, and on matter of the specific gravity of water would be six hundred million Actual Velocities. 85 times as efficient in producing oblateness as the rate of motion found in the original grand rotation. The conclusion we reach is this the ascer- tained rate of the supposed cosmical rotation is totally inadequate to produce a very con- siderable oblateness of the cosmical sphere. It is not our purpose to indulge in extended mathematical calculations, but it will not be deemed amiss to refer to some of the data to be considered. Notice, first, the immensity of the supposed cosmical sphere. Its great circle is about six thousand millions of miles in diameter. How small an angle does the tangent of this vast circle form with the circle itself. Yet the centrifugal force can project the peripheral matter only along the tangent. The velocity of projection at each initial point is 12,000 miles an hour. The arc of the circle passed over in an hour is, as we have seen, only one eleventh of a second. It will, therefore, require the equivalent of a projec- tion continued for one hour to lift the surface outward to the measure of the tangent of an arc of one eleventh of a second, and this, too, 86 THE MODERN GENESIS. without considering the effect of gravity on the projected mass. Is it too much to ask of the advocates of the nebular theory to estimate the force of gravity on the surface of the hypothetical cos- mical sphere, and the exact elevation that could be given to the equatorial region by the centrifugal force? Is it not, indeed, their duty to do this, and thus demonstrate the adequacy of the cen- trifugal force to produce the effects ascribed to it by the theory ? Do they answer, " We have not the exact data necessary to an estimate ? We do not know the exact magnitude of the original cos- mical mass at the time of detaching the plan- etary mass ? We do not know its rate of motion ? We do not know the gravitative force of the original mass ? " Indeed ! Do you not know these things ? Do you assume every thing ? Is every thing to be taken for granted ? And is that science ? Well, whatever you may hereafter do in behalf of the theory, will you show us that a rota- tion at the rate of .00025 of a degree per hour is sufficient to produce even a great degree Actual Velocities. 87 of oblateness in such a body as the original cosmical mass is supposed to have been? When you do that, it will be time to ex- tend the inquiry to the possibility of detaching a peripheral ring by the same velocity Let us dismiss Neptune and glance at the actual velocities of the other planets. The following table shows the mean rate per hour of the orbital motion of each of the planets named : URANUS, .00049 f a degree ; SATURN, .0014 of a degree ; JUPITER, .0034 of a degree; MARS, .021 of a degree; EARTH, .041 of a degree ; VENUS, .066 of a degree ; MER- CURY, .17 of a degree. The sun's axial rotation at the rate of .6 of a degree per hour produces no perceptible oblateness. Suppose the sun to be expanded to the dimensions of the orbit of Mercury and to embrace that planet, meanwhile dropping his rate of axial rotation until it should coin- cide with the orbital rate of Mercury, (.17 of a degree,) would it then exhibit any perceptible oblateness ? 88 THE MODERN GENESIS. CHAPTER VI. DIRECTION OF PLANETARY MOTIONS. Laws of centrifugal projection In what direction must the planet be moving? Where is the plane of original rota- tion ? The sun's rotation Inclination of planetary orbits to the sun's equatorial plane Comets Asteroids Satellites Ratio of the axial rotation to the orbital. IN the preceding chapter we considered the actual velocities of the planetary system, and we arrived at the conclusion that the velocities with which the planets revolve in their respective orbits are not adequate to the production of the peripheral rings con- templated by the Nebular Hypothesis, and that, therefore, these velocities are not such as to account for the origin of the planets on the principles of that hypothesis. But the advocates of the hypothesis also allege that the direction of the planetary mo- tions and of the axial motion of the sun point to the same rational conclusion, the truth of the nebular theory. Thus says Winchell : Direction of Planetary Motions. 89 "Each has continued in an orbit which marks the periphery of the parent mass at the time of the planet's separation. All continue to re- volve in the same direction as the parent mass and the resultant sun. All revolve in very nearly the plane which must always have been the plane of the equator of the mass the as- tronomical ecliptic. All continue to revolve upon their own axes, in the same direction as required by the motion of the parent mass. Can all these be so by chance ? Can these planetary movements thus correspond, and the material constitution of all these bodies be identical, without leaving a profound conviction upon our minds that they have had a common origin and a common history?" The foregoing illustrates how differently men will reason from the same premises. With Winchell, the alternative of admitting that the planetary motions indicate an origin of worlds in the development plan, is the supposition that the planetary system is a chance system. But another man, looking at the same system, would conclude that the happy adjustments of the system simply indicate design, and the direct and immediate agency of a superintend- 90 THE MODERN GENESIS. ing intelligence ; and he would no more think of a natural development of worlds out of fire- mist than he would think of chance. In fact he would think of both suppositions as equally irrational. But in the inquiry we are now pursuing we exclude all reasoning of this kind. To the re- sults we seek, it is all one whether the solar system proclaims the existence of an infinite intelligence the Creator and upholder of all things or not. Our subject is a material subject. The worlds are material worlds. The only forces of which we take account are the forces which are known as material forces, or the forces which inhere in matter and which operate according to fixed laws. Whether these forces, and the laws according to which they act, and the matter on which they act, each or all are the offspring of chance or the offspring of intelligence, is, therefore, of no account in our estimation. We take this planetary structure as it is, we consider its material elements, and the laws which are known to govern them just as they are, and, by the facts which we find existing, we try the Nebular Hypothesis. Direction of Planetary Motions. 91 Our next examination will be of the laws of centrifugal projection. A mass of matter revolving on an axis always generates what is called centrifugal force. If any portion of the mass is free to leave the other portions of the mass, it will be thrown off. If all portions of the mass are equally free to obey the impulse of the cen- trifugal force, all parts will move outwardly with a force determined by the relative situa- tion of the parts. But there is one law of centrifugal projection which is of so great im- portance to our inquiry that we wish to give it in form as follows : THE PROJECTILE ALWAYS MOVES IN A DIRECTION AT RIGHT ANGLES WITH THE AXIS OF ROTATION. Now we demand that when a theory ac- counts for the formation of worlds by cen- trifugal projection, the theory shall be sup- ported by this law of centrifugal projection. Let us assume, with the theory, that this force did detach peripheral rings, that these "rings did become planets, and that " each has continued to revolve in an orbit which marks the periphery of the parent mass at the time of planet's separation," then in what 92 THE MODERN GENESIS. direction should we expect to find planets now moving? Is not the answer evident ? What is the law ? The direction of the projection is at right angles with the axis of rotation. Then the plane of a planet's orbit must be at right angles with the axis of the cosmical sphere. And that is to say that the plane of the planet's orbit and the plane of the cosmical equator must be exactly coincident. There can be no inclination of the one plane to the other. In the nebular theory the only force opera- ting to give the detached planet an orbital motion is the centrifugal force. Could we find other planetary bodies occupying situations in space outside this plane, we should then have in gravitation a force by which the planetary orbit might be deflected from the plane of original rotation ; but we are obliged to ex- clude all such suppositions. We must keep in mind that "All the marvelous uniformities of the solar system are but the progeny of that primitive impulse which originated the grand rotation" That there are perturbations in the orbital movements of the planets which can be traced Direction of Planetary Motions. 93 to their mutual attractions, and that some of these perturbations are lateral, is known to all astronomers. And so carefully has this sub- ject been studied that, by the perturbations of Uranus, Leverrier and Adams, independent- ly, calculated, the location of the planet Nep- tune, which, as yet, was unseen. But has any one estimated the disturbing force of the attraction of one of the fixed stars upon one of the planets ? Will any one aver, as a fact, that such stellar attraction does so affect the movements of a planet as to change the plane of its orbit ? The advocates of the Nebular Hypothesis do not, so far as we know, make any such claims. All planetary pertur- bations, then, must arise from planetary at- tractions. But if the nebular theory be true, there never can- arise such a collocation of the planetary masses as would give rise to orbital inclinations. The grand rotation of the original mass ele- vates the cosmical equator. It does not it cannot elevate any other region so much as that. If a ring could be produced at all it must be exactly over the equator, and its mass must extend equally on both sides of it. Thus 94 THE MODERN GENESIS. equipoised, the attraction of the original mass will not disturb its equilibrium. There is no other body whose attraction will sensibly affect it. Its own momentum, after it is detached, will carry it in the direction given by the projectile force. The centrifugal force projects it in a plane which is at right angles to the axis of rota- tion. Then it must forever move in that plane, unless some other force lays hold of it to turn it aside. But where is that plane ? No matter where. If ever there was an original cosmical sphere revolving axially, and giving birth to planetary masses by the operation of the cen- trifugal force, then those planetary masses must have been projected in the equatorial plane of that cosmical sphere, and there we are authorized to look for them to-day. All causation is within. Planetary history is a history of evolutions. Looking at the solar system from this stand- point of theory, (the nebular theory,) and re- calling to mind the unchanging law of cen- trifugal projection, we are prepared to find uniformities. Nay, we demand uniformities. Nothing but uniformities will meet the re- Direction of Planetary Motions. 95 quirements of the theory and of the law. We are advertised that there are marvelous uniform- ities. " Each has continued to revolve in an orbit which marks the periphery of the parent mass at the time of the planet's separation. All continue to revolve in the same direction as the parent mass and the resultant sun." Wonderful coincidences ! Yet we expected them. Knowing that a world was projected from the parent mass by the centrifugal force, we 'could not for a moment dream that it could move in any other direction than that of the parent sphere. If the axial rotation of the cosmical sphere was from west to east, then the orbital rotation of the planetary mass must be from west to east. It will be marvelous, in- deed, if it be in any other direction. And, if it take an axial rotation also, (as it probably will,) then that axial rotation will also be from west to east. The first-born planet will be found moving in the plane of the cosmical equator, and its own equatorial plane will be coincident with its orbital plane. And the next planet will revolve in the same plane; and the next, and the next. All planetary motion will be in one plane. It must be so 96 THE MODERN GENESIS. upon the fundamental postulates of the Nebular Hypothesis. The theory must abide by its own postulates. To assume that the direction of the axial rotation of the original cosmical sphere has undergone a change, is to assume a material point contrary to the law. To assume that the orbital or axial rotation of a planet has de- parted from its original plane, is also to assume a material point contrary to the law. If the Nebular Hypothesis be dismissed, and we conceive of a planetary system in which, from the first, there is axial motion in different planes, and orbital motion in different planes, then we can see how there may arise changes of motion out of which shall come sifch phe- nomena as the precession of the equinoxes for instance. But on the principles of the Nebular Hypothesis we cannot admit the possibility of any such phenomena. Let us now institute a more detailed ex- amination of the solar system, with special reference to the direction of planetary motion. We commence our examination at the center of the system, because, by the terms of the Direction of Planetary Motions. 97 theory " the sun is only the residual portion of the cosmical mass, still maintaining an in- conceivably high temperature, simply because so vast a body of matter has not yet had time to cool off." Winchell. We are fortunate in finding the " residual portion of the cosmical mass ; " and it is only fair to acknowledge that we find 1st. That it is very hot. 2d. That it is very light only a little heav- ier than water. 3d. That it is still a vast body, for its vol- ume is five hundred times as great as the com- bined volumes of all the planets, and its mass is seven hundred and forty-five times as great as theirs. It is as if a mass of seven hundred and forty-six pounds had lost one pound. 4th. That, huge as it is, it is in motion on its axis. And this last circumstance is what we are just now most concerned to observe. At pres- ent we care nothing about the rate, but we notice particularly the direction of its motion. The sun rotates from west to east. Not exactly from west to east, as we see west and east on the earth, but in a general sense. 98 THE MODERN GENESIS. Now this axial rotation of the " residual portion," we assume, must be the original cos- mical rotation, at least as to direction. If it be not the original direction of the grand rotation what has changed it ? All motion generates force. Force can only be overcome by force. Given the cosmical mass in motion in any direction, we cannot conceive of a change in the direction of that motion without the ex- penditure of adequate force. What force could change the direction of the axial rotation of the sun ? We have also shown that, on the principles of the nebular theory, there could be no change of plane of a planet's orbit. The direction of the rotation of the cosmical mass is therefore known. We have only to follow the plane of the sun's equator out into the heavens to the distance of Neptune and we will see exactly where the " periphery of the parent mass " was " at the time of the planet's separation." Now watch the progress of Neptune. Does it keep along that plane ? No, it is north of it. But it is approaching it. Now it is in it. But it crosses it, and goes on south of it. But it Direction of Planetary Motions. 99 comes back again and recrosses it. And so, period after period, it crosses and recrosses the plane of the cosmical equator. How was Neptune produced ? By the cen- trifugal force? How, then, is the plane of his orbit inclined to the plane of the cosmical equator nine degrees? We think this must be an illusion, and we proceed. We shall find Uranus, Saturn, Jupiter, and Mars, all revolving in the same plane, the plane of the cosmical equator. Preposterous ! Reader, did you say that ? Why preposterous? Because every body knows that the planetary orbits are all inclined to the plane of the sun's equator. Indeed. Then, in the light of the facts our expectation is preposterous. But by the premises of the nebular theory our expectation is only reasonable. What shall we do? If we take the facts we must throw away the theory, unless the facts can in some way be accounted for. There are two things we cannot do: we cannot set aside the facts, and we cannot de- stroy the law of centrifugal projection. No. We must admit the facts : we must adhere to the law. It is a law of universal application. ioo THE MODERN GENESIS. The centrifugal force acts at right angles to the axis of rotation. It never acts otherwise. This law of motion cannot be subordinated to a theory of world formation. If the theory cannot abide the test of the law, so much the worse for the theory. Sometimes the advocates of the nebular theory speak of the planetary masses as being " torn away " from the cosmical mass, and yet none of them really contemplate the act of detaching as any thing but an effect of the centrifugal force. No outside force is alleged. The centrifugal force, which accumulated in the peripheral matter, alone has the credit of detaching it. Therefore the detaching force is the directive force, which the planet must obey. What, then, is the direction in which each of the planets moves ? And how do they agree with the original grand rotation ? The planetary orbits are all inclined to the plane of the sun's equator, as follows : Mercury, 14 degrees; Venus, 13 degrees; Earth, 7^ degrees ; Mars, 9 degrees ; Jupiter, 8 degrees; Saturn, 10 degrees; Uranus, 8 degrees ; Neptune, 9 degrees. Direction of Planetary Motions. 101 The asteroid also belong to the solar system. How many there are of them we know not. It is conjectured that there may be several hundred, or even thousands, of them. They are small planets. They are revolving around the sun in orbits of varying eccentricity and inclination. One of them Pallas revolves in an orbit whose plane is inclined about forty degrees to the plane of the sun's equator. One other class of objects demands our at- tention. The comets revolve around the sun, and though they are known to be exceedingly light, aeriform bodies, yet they must be recog- nized as erratic members of the cosmical sys- tem ; wandering fragments of the attenuated world stuff; and our inquiry is incomplete if it do not ask, How did they originate? How were they cast off from the cosmical sphere ? We shall hardly make a separate theory for these bodies. They belong to that material fabric which we are studying. They contain the same elements, at least in part. They have orbital motions. They began their career under some impulse. What was it? If the solar system came out of an original cosmical condition, like that portrayed by the nebular 102 THE MODERN GENESIS. theory, then the comets were once portions of the nebular mass, and in some way were pro- jected from it. And we must refer their separate existence to the centrifugal force. Well, in what direction do they move ? In many directions. Some have a direct motion from west to east in planes only slightly in- clined to the ecliptic. Some revolve at nearly right angles to the plane of the ecliptic, and others have a retrograde rotary motion. And now, having taken this general view of the orbital motions of the solar system, what is our conclusion ? Have we found the marvelous uniformities ? Have we not rather found marvelous variations ? The advocates of the nebular theory are not ignorant of these variations nay, we should say when referring them to that theory, these discordances. How, then, do they explain them or account for them ? They do not ac- count for them. They appear to regard them as unimportant trifles. They seem amazed at the general uniformity of the system, as if uniformities were not to be expected from the premises of the theory. They seem to Direction of Planetary Motions. 103 be totally unimpressed by the exceptional motions. Thus far we have considered only the mo- tions of the primary planets. Let us now look at the orbital rotation of the satellites. The satellites, according to the theory, were pro- jected from the planetary masses in the same manner in which the planets were projected from the original mass. If they were so projected, we are authorized, by the law, to look for them in the planes of their planets' equators. Taylor, in the discussion of " The nature and origin of force," refers to the moon as " an out- lying portion of the earth's former equator." But the moon's orbit cuts the plane of the earth's equator at an angle of nearly twenty- nine degrees. The satellites of Uranus and Neptune exhibit a startling exception to the general order of rotation. In these cases the direction of the rotation is reversed, the sat- ellites moving from east to west. Professor Winchell sees no difficulty here, however, and nothing incompatible with the nebular theory. He says, " In fact, the plane of the satellites is tilted up at an angle which iO4 THE MODERN GENESIS. exceeds the perpendicular by about eleven de- grees ; thus the whole system is nearly inverted, and the motion of the satellites, like that of the hands of a watch lying face downward, seem to be reversed. A moment's reflection will convince us, however, that this is an illusion. The motion is normal. The attitude of the system only is extraordinary." It only requires " a moment's reflection." " In fact, the plane of the satellite is tilted up." " The attitude only is extraordinary." Now, to us, this seems the veriest trifling. Why is not this tilting up accounted for? That it is tilted up is a circumstance that is incompatible with the Nebular Hypothesis. What caused it? How came the attitude to be extraordinary? The attitude only is cer- tainly a matter of some moment. The Uranian system is not contemptible for its magnitude. It would require something of a force to invert that system. One would suppose that an event of so much importance in planetary, history should have a little more serious consideration than a " mo- ment's reflection." It is a fact that if the planets originated as Direction of Planetary Motions. 105 this theory claims, the plane of these satellites has been tilted up. Then some force must have tilted it. It is not necessarily the province of the as- tronomer to account for these exceptional motions. He has met all his legitimate obliga- tions when he has fully described them. But when an astronomer assumes the rdle of his- torian of planetary evolution, then it becomes incumbent on him to account for every excep- tion to that order which his historical theory requires. But Winchell alleges that the " motion is normal," yet what he means by normal in this connection we are at a loss to understand. Does he mean simply that the motion is ro- tary ? That the satellites revolve in orbits ? Or does he mean that they revolve in the same direction in which the parent planets perform their axial rotation ? If so, does he not as- sume the direction of their rotation ? To our mind that motion is normal which is according to known laws laws of velocity and laws of direction. If a body is put in motion by the explosive force of gunpowder, and it is made to take the io6 THE MODERN GENESIS. direction of a certain object, we consider its motion normal so long as its flight is such as could have been calculated for it by one know- ing its weight and its initial velocity ; but if it go to the right or left, and no cause can be assigned for this change in its direction, can we say it is normal ? But if the flight of the pro- jectile be at a right angle with the line of pro- jection, or if it should fly toward the rear, what would we say ? Who could explain that ? In ancient times the sling was employed in warfare. But the skill of the slinger consisted chiefly in two elements: the ability to revolve the sling in the perpendicular plane, and the tact to release the projectile at the exact point in the circle, at which its direction would be toward its object. The centrifugal force must do the rest. Now suppose the plane of rotation to be per- pendicular, and yet the flight of the projectile to be greatly deflected to the right or left. Is that a normal motion ? In the case of Uranus and its satellites the latter are affectionately contemplated by the nebular theory as the children of the former. Direction of Planetary Motions. 107 The process of their derivation is particularly described. "Similarly the planetary masses detached rings which became their satellites." " But what again of our family of infant planets ? Each sprang forth, a globe of igne- ous vapor, like their common mother. Each began to repeat the process of cooling, con- densation, and accelerated rotation. In the cases of the larger, the cooling had not reached the point of liquefaction before the rotation had become sufficiently rapid to detach from one to seven rings, which in turn became sat- ellites revolving about their planets. The larger planets have had time to detach the greater number of rings. Our earth threw off but one, and became too rigid to repeat the process. " Mars, Uranus, and Mercury all smaller than the earth attained the rigid condition before their acquired velocity had separated the periphery. Their nights are consequently unillumined by the presence of a moon." WiNCHELL, Sketches of Creation. Notice in every case, the manner of produc- ing a planet is the same. The centrifugal io8 THE MODERN GENESIS. force detaches a ring from the periphery of the revolving cosmical mass. The one thing which is essential to the accomplishment of this work is " sufficient velocity." When de- tachment takes place, all that sufficient velocity attends the detached mass. It goes forward in the route determined for it by the centrifu- gal force. But the satellites of Uranus decline to obey the law, and turn back on their course, and making a circuit, so to speak, make an oblique and retrograde path of their own, with- out law and without warrant. It is not an illusion. It is a fact. The satellites are not revolving where they must revolve if the nebular theory be true. And the fact is against the theory. The same fact is observable in the satellite of Neptune. Its one satellite revolves around the planet from east to west. The first born of satellites, like the first born of man, re- verses nature's own decree, sets at naught the law, and sports itself in opposition to authority. The phenomenon also remains unaccounted for by the nebular theory. Rather, we should say, the fact stands against the theory and Direction of Planetary Motions. 109 cannot be reconciled with it. Disappointment meets us at every step. We started out to examine the actual mo- tions of the solar system, assured that all planetary motion was the progeny of an orig- inal grand rotation of the cosmical mass ; and hence concluding that it would be found obe- dient to the laws of centrifugal projection. We find the planetary motions random mo- tions. We cannot reconcile them with the law. There is not a single instance of con- formity to it. Such a thing as uniformity is not to be found. Planets revolve in planes that are slightly inclined to each other ; comets dash through the planetary regions in orbits whose planes are perpendicular to those of the planets; asteroids swing about in many direc- tions, cutting through other planetary planes at large angles ; and satellites crown the be- wildering confusion with absolutely retrograde movements. We can come to but one con- clusion. The origin of planetary motions is not accounted for by the nebular theory. There is not a single instance of orbital mo- tion that is what it must be to be in harmony with the fundamental postulates of that theory. no THE MODERN GENESIS. We have yet to consider the axial rotation of the planets and their satellites. The axial rotation of a planet, according to the theory, as we have before seen, is the prod- uct of the same impulse which gives it an or- bital motion. And this, it has been claimed, is at once illustrated and proven by Plateau's celebrated experiment. Admitting the truth of this theory, we sub- mit that it would result that the orbital plane of each planet and satellite must coincide with its equatorial plane. Then the proposition which we submitted early in this chapter would be verified ; all planetary motion must be found in one plane. True, then, there would be no changes of seasons on the planet's sur- face ; but what of that ? The grand rotation is not an intelligent designer, prompted by be- nevolent considerations to shape a system for the benefit of any existences whatever. The grand rotation is simply an inexorable pro- jector of worlds. It can only project them in one plane. It can go no further. But the planets do not revolve in one plane. Every planetary orbit cuts the plane of the sun's equator at some angle. The satellites Direction of Planetary Motions. 1 1 1 do not revolve in that one plane. Their orbits not only cut the plane of the sun's equator, but they also cut the planetary orbits. So, also, the axial motion disregards the law. The equatorial plane of every planet, so far as we know, cuts across the orbital plane. The inclinations, at which they cross, vary greatly, but the least of them is too great to harmonize with the nebular theory. The following table exhibits the inclination of orbital plane to equatorial plane : Mercury, 70 degrees ; Venus, 75 degrees ; Earth, 23^ de- grees; Mars, 28| degrees; Jupiter, 3 degrees; Saturn, 26f degrees. The inclination in the cases of Uranus and of Neptune is unknown. Looking at these figures we are constrained again to ask, Are these the marvelous uniform- ities that were announced as observable in the solar system? Are they not unaccountable diversities? What force tilted up the axis of each planet, so that its axial rotation shall be in another plane than that of its orbit ? How is it that Venus has been tilted up to the extent of seventy-five degrees ? True, Venus is not a very large planet, and yet it certainly would require force to put it in motion, and an ii2 THE MODERN GENESIS. equal force to stop it when once in motion. But it must have been moved seventy-five degrees, and then stopped, for its axis is fixed in direction, that is, it is parallel to itself, at all points of the orbit. The same remarks will apply to all the planets whose axial inclination is known. Another problem requires solution by the principles of the nebular theory : What must be the ratio of the axial to the orbital rotation of any given planet f We think it evident, that if the centrifugal force projected a planet into space, the orbital velocity of the detached mass, at the moment of detachment, must have been the equatorial velocity of the mass from which it was de- tached. Exactly that : no more, no less. Now if we suppose the detached mass to be gathered together into a planetary sphere while moving forward in the tangent of the circle of rotation, we must allow that it will acquire an axial rotation, because its outer portion, that is, that portion which is farthest from the axis of the original rotation, must move faster than that portion which is nearest Direction of Planetary Motions. 113 that axis, and so the planet must turn upon) its own center. And the difference between its exterior velocity and its interior velocity would determine the rate of its axial rotation. The more the direction of the planet's flight is deflected from the tangent toward the circle the less would be that difference ; and, there- fore, it would follow that the more circular the orbit of a planet the less rapid ought to be its axial revolution, if it has arisen on this plan, which is the plan of the nebular theory. But in any event it will be seen that a definite ratio must have existed between a planet's orbital motion and its axial motion. A very simple geometrical figure would illustrate this proposition. Moreover, the nebular theory proceeds on the assumption that the same force^ that is, the centrifugal force, has given to the planets severally both axial and orbital mo- tion ; and it is for this reason because a law of development is supposed to exist that a history of planetary origin is supposed to be possible. And thus, Winchell says, "This community of conditions, this unanimous obe- dience to one code of physical laws, implies that all these bodies are urged onward through ii4 THE MODERN GENESIS. a common history, and have probably had their starting point in one common state of matter." "Thus the present state of the solar system is a living picture of the entire history of a sin- gle planet." We are searching for that code of physical laws. We know something of the laws of at- traction, of the radiation of heat, of the veloc- ity of falling bodies, of the centrifugal force ; but here arises a case in which we think there must be a law regulating the relative rates of the two kinds of planetary motion. We do unhesitatingly affirm that if the planets have been projected from a revolving mass, as the nebular theory assumes that they have been, then there must be a mathematical ratio be- tween their orbital rotation and their axial rotation, and any ordinary geometrician as- suming the diameter of the cosmical sphere to be a definite measure, and the diameter of the detached mass to be another definite measure, and knowing the detaching velocity can cal- f culate what the axial rotation must be. If the i orbital rotation be slow, the axial rotation must be correspondingly slow. If the orbital rotation be rapid, the axial rotation must be Direction of Planetary Motions. 1 1 5 correspondingly rapid. We have a right, then, in advance, to predict one thing respecting the axial rotations of the planets, to wit, that they will be found to increase in velocity as we approach the sun, as we know that their orbital velocity increases. Do we find our prediction verified as we travel inward from Neptune? The following table exhibits the actual rates of these two kinds of rotary motion in all the planets whose axial motion is known : TABLE. Rate of Orbital Motion. Rate of Axial Motion. Saturn Jupiter Mars .0014 degrees. .0034 " .021 " .041 .066 .17 34.5 degrees per hour. 36. " 15.7 " 15. " " " 15-3 " 14. Earth Venus Mercury Thus it appears that there is no common ratio existing between these two kinds of mo- tion. The large, remote planets, Jupiter and Saturn, with comparatively slow orbital mo- tion have very high rates of axial rotation, and Mercury, with the highest rate of orbital, ii6 THE MODERN GENESIS. has the lowest rate of axial, rotation. These facts are inexplicable. At least they are inexplicable on the principles of the neb- ular theory. If that theory were true, these things could not be. The facts are against the theory. Densities. 117 CHAPTER VII. DENSITIES. Probable disposition of the cosmical matter on theoretical principles. AMONG the facts of the solar system which are supposed to corroborate the nebular theory, the advocates of the theory find this the density of the outer planets is less than that of those nearer the sun. Professor Winchell says: "It is reasonable to suppose that the older planets are composed of a smaller proportion of the denser elements than the newer planets, since they are formed from the peripheral portions of the original fire- mist, while it is likely the denser portions gathered about the center, and entered, to a larger extent, into the constitution of later rings. The lower specific gravity of the older planets may be partly attributed to this cause." We think it evident, that in a spherical body, whose particles are free to move among n8 THE MODERN GENESIS. each other situated as the nebular theory supposes the cosmical sphere to have been situated the matter of least specific gravity must be most remote from the center, and the matter of greatest specific gravity must be gathered about the center. This is exactly what we see fluid matter of all kinds do, under ordinary circumstances, on the earth. Matter in a fluid state, when thrown together, arranges itself into different strata, unless chemical combination take place and prevent such arrangement. For the most dense will sink to the lowest place, and lift out whatever lighter matter occupied the place ; the matter of next greatest density will rest on the denser, and so on upward ; the less dense will be sup- ported by the more dense, until, at the top, will be found the least dense of all. At ordinary temperatures mercury, water, and various oils afford familiar illustrations of this law. Thus mercury will settle through water, and will support it. Water will settle through air, and will support it. And thus we may conceive of the sublimated materials which composed the original cosmical mass, obeying their resident gravitative force, and Densities. 119 gradually forming distinct strata ; and espe- cially so, since the elements existed hypothet- ically in a dissociated state. Moreover, since, as Winchell truly intimates, " the states of matter are but the product of temperature and pressure," and since pressure is known in certain cases to counteract temperature, we may conceive of the denser elements, which go to the center, as subjected to pressure, which would change them from the vaporous to the liquid condition, while the remote lighter el- ements still remained in the gaseous condition. If, then, the cosmical sphere be supposed to have a rotary motion, we shall readily see that the lighter elements must be more powerfully affected by that motion, because they are near- est the surface of the revolving sphere. We are willing to adopt stronger language than Winchell employs, and say, // must be so. As the water would rise through mercury, as air would rise through water, and as the lighter hydrogen gas would rise through air, so it would seem the lighter cosmical elements must have risen to the higher, that is, the outer re- gions ; and as it was of the peripheral matter that each world was successively formed, the 120 THE MODERN GENESIS. older planets must have been, at the time of their formation, the lighter planets, if formed in the manner set forth in the nebular theory. Then the oldest planet must have been formed of the lightest matter, and its satellite must have been formed of the lightest of that light- est matter. The next oldest planet must have been composed of the lightest of the residual matter, and its satellites must have been com- posed of the lightest of that lightest residual matter, and so on. Yes, we can only agree with Winchell in this position, unless we go farther than he, and add, there must be a regular gradation of densities in the planetary system. Theoret- ically, no variation of densities is admissible, except a regular gradation from the least dense in the most remote to the most dense in the planet nearest the sun ; but such a grada- tion seems to be theoretically necessary on the premises assumed by the nebular theory. But let us suppose that the elements compos- ing the cosmical mass were so affected by the inconceivably high temperature that the disso- ciation was attended with promiscuous inter- mixture, even to the outmost limits of the Densities. 12 1 mass so that the whole mass was of uniform density, what effect must follow, theoretically, in the condition of each of the planetary masses? In that case, as in the other, we must still affirm that at the time of separation the planets must have been of regularly graded densities. Moreover, we are happily able in this case to tell, with very considerable accu- racy, what the ratio of the density of each planetary mass must have been to that of the next preceding, and to any, indeed, of the whole number. For the nebular theory as- sumes that the orbits of the planets mark the limits of the cosmical sphere at the times when the respective planetary masses were detached. Grant this assumption. Then it follows that whatever the density of the cosmical matter was at the time of the separation of the Nep- tunian mass, by the contraction of the sphere to the limit marked by the orbit of Uranus, the volume of the cosmical sphere was shrunken to less than one fourth its previous measure. That sphere, of which the orbit of Neptune is the equatorial line, is 4.8 times as large as that whose equator is measured by the orbit of Uranus. But the contraction of volume is 122 THE MODERN GENESIS. the condensation of the matter. If, then, the elements be supposed to have remained disso- ciated and intermixed, so that the whole mass was of uniform density at the time that the Uranian mass was detached, it is evident, that after allowing for the absence of the Neptu- nian mass, the matter of the Uranian system was more than four and a half times as dense as that of Neptune. But after detaching the Uranian mass the cosmical sphere again con- tracted to limits marked by the orbit of Saturn, and then the Saturnian mass was de- tached, and its matter was eight and a half times as dense as that of Uranus, and thirty- eight times as dense as that of Neptune. We shall hereafter have occasion to refer to this point again, in speaking of the relative masses of the planets. It is not necessary, therefore, to extend our examination further into details at this stage of our inquiry. We have, we think, made it clear to every intelli- gent reader, that upon the assumption of uni- form density of the cosmical substance, and the formation of worlds on the plan of the nebular theory, the second planetary mass must have been four and a half times as dense Densities. 123 as the first, the third eight and a half times as dense as the second ; and these three plan- etary masses were, in their density, as i. 4^. 38. These numbers, it should be remembered, in- dicate the original planetary densities. Now the present actual densities are not supposed to be like the original densities, because the same processes that increased the density of the original cosmical sphere are supposed to have increased the density of each planetary mass also. Moreover, on the supposition that the contraction of the mass was the result of the cooling of the mass, it is evident that the small planetary masses must have contracted with a rapidity as many times greater than that of the parent mass as they were times smaller than that. Now the Neptunian mass was only * T ,| TT part of the original cosmical mass. It would, there- fore, cool off twenty thousand times as fast as the original mass, and while the original mass was cooling and contracting to the limit at which its density was four and a half times as great as at first, the planetary mass would cool off and contract 4^x20,000, or ninety thousand times as much. So we are authorized to say 124 THE MODERN GENESIS. that at the time of the separation of the Ura- nian mass the mass of Neptune was twenty thousand times as dense as Uranus, and nine- ty thousand times as dense as at its own birth. In like manner, after the separation of the Uranian mass, three masses were undergoing the same process of cooling and contracting until the Saturnian mass was detached. The Uranian mass is about a j.Vtn!' of the residual cosmical mass. Therefore it will cool and con- tract twenty-five thousand times as fast as the parent body. But the parent body contracts so much that its density is eight and a half times as great as it was when Uranus was de- tached. The density of Uranus must, there- fore, be 8x25, ooo, or two hundred thousand times as great as it was at the time of its de- tachment, and twenty-five thousand times as great as the density of the Saturnian mass. And so, through unknown ages, the planetary masses have been cooling off and their density increasing. Now this process of cooling and contracting would produce these proportionate effects for a limited period. But the time would come in the history of each separate mass that it Densities. 125 would cease to shrink perceptibly, and thence- forward the relative densities would not be referable to temperature as their cause. With these preliminary reflections we are prepared to make an examination of the actual densities of the planetary masses. It is a fact that the remote planets are less dense than those nearer the sun. The density of Neptune is T 9 g- ; that of Uranus is I. According to the nebular theory Neptune is the oldest of the planets. The period that intervened between the time of its formation and that of the formation of Uranus no one pretends to know, but it is assumed that it was an immense period. We may be sure it was millions of ages, for in that period the cosmical sphere contracted from a diameter of six thousand millions of miles to one of three thousand five hundred millions of miles. Then Uranus was thrown off, and since that time they have been cooling and contracting together. Now have these two planets reached that point of congelation at which the density is not indicative of temperature, or have they not ? According to the nebular theory the three factors original density, original volume, and 126 THE MODERN GENESIS. time are to be considered as determining the present density of a planet. Of these three factors we know exactly nothing. It is the practice of nebular theorists, however, when difficulties arise, to assume that they would speedily disappear could we only know the truth about original volumes and time. The present densities of Neptune and Ura- nus, as we have seen, are T 9 7 and i. We have also seen that there was a time, if this theory be admitted, when the density of Neptune was twenty thousand times as great as that of Uranus, and since that time the two bodies have been cooling off and contracting together. How is it, then, that Uranus has overtaken and passed by Neptune, so that now the den- sity of Uranus is the greater ? Shall we ac- count for it by alleging the inferior mass of Uranus? As their masses are to each other as thirty-three to twenty-five, we submit, for the present, that the explanation has been found. In going from Neptune to Uranus we went from a less density to a greater, and we have had an explanation of the fact. We now pass Densities. 127 on and examine the density of Saturn. We remember that the cosmical matter out of which the Saturnian mass came was eight and a half times as dense as that out of which Uranus came. How is it, then, that we find Saturn's density only three fourths as great as that of Uranus ? The answer is ready : Saturn is a younger and a larger body than Uranus, so that, though her original density was eight and a half times as great as that of Uranus, yet at the time of Saturn's birth Uranus had already attained considerable age, so great, indeed, that during the existence of Uranus the cosmical mass had acquired a density eight and a half times that with which Uranus started out. But during all that time Uranus was outstripping the parent mass in the race of condensation, because, being only -5-5^-5-5 as large as the parent mass, Uranus had con- densed twenty-five thousand times as fast ; and so, when Saturn sets out -on his separate career, Uranus has already attained a density twenty-five thousand times as great as Saturn's. Of course, then, we must not expect Saturn to overtake Uranus in the process of conden- sation. Why not? For two reasons: i. Be- 128 THE MODERN GENESIS. cause Uranus has so much the start. 2. Be- cause Uranus, being so much smaller than Saturn, will continue to condense more rapidly than Saturn, and thus widen the distance be- tween them. The mass of Saturn is more than seven times as great as that of Uranus. Uranus, therefore, will continue to cool off and condense seven times as fast as Saturn. Be- hold the result. Uranus, at the outset of Sat- urnian history, twenty-five thousand times as dense as Saturn, goes on through all the cor- responding periods of planetary history seven times as rapidly as Saturn. We must change the form of our question and ask, How is it that Saturn is so heavy ? How is it that the density of Saturn is so great ? Unless we con- clude that Uranus has long since reached an unchanging density, Saturn has a relative den- sity many thousand times too great. If we assume that Uranus and Neptune have both reached a condition of unchanging density, then their relative density ought to be as one to four, Neptune being one. But Neptune is nine tenths. Uranus is one. Difficulties thicken, but let us go forward. Let us compare Saturn -and Jupiter. The Densities. 1 29 residual cosmical mass, after allowing the removal of all the matter of Saturn, was about three thousand five hundred times as great as the Saturnian mass. It had con- tracted to the limit marked by the orbit of Jupiter, and in so contracting its density was multiplied by six and a half. The matter of which Jupiter was constituted was, therefore, six and a half times as dense as the original matter of Saturn. But we must not forget that while the great parent mass was thus be- coming six and a half times as dense, Saturn, which was only g-jW the mass of the cosmical parent, was increasing in density three thou- sand five hundred times as fast as the parent mass. At the very moment, therefore, that the Jovian mass was detached, the density of the Saturnian matter was three thousand five hundred times as great as the Jovian. Now how will their contemporary history af- fect their relative densities ? The mass of Jupi- ter is three hundred and one, while that of Sat- urn is ninety. Jupiter is, therefore, more than three times as large as Saturn. Then Saturn will contract and condense more than three times as fast as Jupiter. Will Jupiter ever 9 130 THE MODERN GENESIS. overtake Saturn? Never until Saturn shall reach the point at which density undergoes little, if any, change. But Jupiter is already twice as dense as Saturn. We found Saturn, when compared with Uranus, much too dense for the theory. We now find Saturn too light. We ask Professor Winchell to account for these discrepancies. Compare which planet we will with Saturn on the premises of the nebular theory, we are mocked by the results. In pursuing this line of inquiry we have fol- lowed exactly the line pursued by Winchell in comparing the earth and the moon. The fol- lowing is almost a quotation : " Saturn is only one third as large as Jupiter, and, therefore, it will cool off three times as fast. Its historic periods will be correspondingly shorter. And it will pass through its various stages of refrig- eration so much more rapidly." There is no regular gradation of densities. There is no indication that there ever was such a gradation. The densities of the larger plan- ets are inexplicable on the principles of the nebular theory. And it is immaterial which Densities. 131 supposition we shall make that the lighter cosmical matter was the peripheral matter, or that the cosmical matter was of uniform den- sity in either case we ought to find a regular gradation of densities in the planetary system, but we do not find it. Saturn is especially inexplicable. Associ- ated with his elder brother, Uranus, in com- parison he puts on an extravagant amount of gravity, a gravity utterly unbecoming his com- parative youth. Associated with his younger brother, Jupiter, he is guilty of equally extrav- agant levity, utterly unbecoming to his ad- vanced age. Young or old, Saturn fails to render support to the Nebular Hypothesis. 132 THE MODERN GENESIS. CHAPTER VIII. DENSITIES CONTINUED. Existence of the same elements in different planets In the sun In the stars. WE have assumed the existence of bodies of matter in gaseous condition in the heavens. We now further assume that these gaseous bodies are composed of elements that constitute the earth. We also suppose that these same elements are present in the sun and in the remotest fixed stars. These suppo- sitions are not new ; nor are they of special value to any cosmical theory. And yet the advocates of the nebular theory have recently experienced wonderful ecstasies from the fact that the spectroscope had assured us, to some extent, of the truth of this old supposition, and the existence, in the different planets, of the same elements has been mentioned as a ground of belief in the nebular theory. But does the admitted fact give support to the theory? Who has ever raised a question that Densities Continued. 133 the sun and planets were material bodies? Who has denied that the stars were material bodies ? Who has denied the materiality of the nebula ? But does the fact of materiality prove " a common origin " of all these bodies in the sense in which those words are used in the nebular theory? Admitting that there are real nebula in the heavens bodies of self-lu- minous vapor does it follow that all planetary bodies were once masses of vapor? Suppos- ing the original condition of each of the plan- etary bodies to have been igneous, does it fol- low that it must have been gaseous ? But even if it did follow that the original condition was gaseous, would it follow that each body had been separated from the others by such a process of mechanical evolution as this nebular theory proposes? If the sun is composed of the same elements as the earth, does it follow that the earth has been derived from the sun ? If all the planets be found to contain the same kind of matter that the sun contains, must we, therefore, conclude that all the plan- ets were at the same period embraced in the sun ? Then we must go further. Identity of 134 THE MODERN GENESIS. material elements existing in any two of the heavenly bodies proves a common origin, and at some time residence in one common mass. We must, then, carry our generalization to the common origin of all the stellar bodies. True, some of them may be so far distant from us that we cannot absolutely determine their ma- terial constituents; yet, wherever we have been able to bring a star under the inquisition of the spectrum analysis it has given an an- swer touching its constituent elements; and we may be justified in assuming that the same elements that constitute the earth are present in every star as well as in the sun. Then there must have been a time when the whole material universe, embracing the countless millions of stars, all the thousands of nebula, all the comets, and all the planets, were in the condition of igneous gas, filling all that inconceivably vast sphere within which the fixed stars are situated. Then there were , no stars and no interstellar spaces. All was one vast furnace of inconceivably high temper- ature. The volume of the original cosmical mass, which is now formed into our solar sys- tem, must have been so much greater then Densities Continued. 135 than it was at the birth of Neptune, that a thousand cubic miles of it would not equal a grain in weight. Yes, accepting the nebular theory and its method of reasoning, we are conducted to this conclusion. The cosmical matter existed in an unbroken mass, as exten- sive as the universe. Look at the argument. The planets are composed of the same el- ements that compose the sun. Then they must have had a common origin. The sun contains the same elements which are con- tained by the stars. Then they must have had a common origin. We might affirm that this sameness of con- stituent elements indicates a common origin in the fiat of one infinite Mind. We might infer the existence of a general plan in the adjustments of stellar relations. We might reach the conclusion that the general likeness of material features, so far as known, justifies the conclusion that an intelligent purpose was at the bottom, and an intelligent, constant supervision is exercised over the whole mate- rial universe by one Supreme Will. We might add that we know not what office the nebula 136 THE MODERN GENESIS. have in the economy of nature, that if the uni- verse be the work of Infinite Wisdom they have some office, and that if it be not, then nothing has any office, and all efforts to find a system of nature are idle. But we will not urge such possible reflec- tions. We repeat, as we have observed be- fore, we are engaged in a strictly material study. We assume that there is a material unity in the universe. Whether any God ex- ists or not, there is material unity, and we will not be diverted from our pursuit by any fear that our discoveries may possibly be inimical to religion. We have the proofs that worlds are bound together by gravitation in a great system. We have in light, which issues from a star so remote that it is years reaching us, the same actinic, the same illuminating, and the same thermal action that belongs to the light of our own sun, and we find it obedient to exactly the same laws of refraction and reflection. . Whatever else men may differ about, this would seem beyond dispute, all celestial and terrestrial bodies constitute one grand material unity. The material relations are intimate. Densities Continued. \ 3 7 All material things are constantly acting upon each other. But does it follow that all these bodies once slumbered in the bosom of a universal nebular mass? Does it follow that they have been mechanically evolved? Does it give prob- ability to the suspicion of an original grand rotation of the whole universe as a gaseous mass, by which all existing stars and nebulae became separated from each other? Does it follow that our solar system has thus separately been evolved? Not at all. Not one of all these facts of nature hints at any such thing. But if we should concede the existence of the universe originally in such gaseous state, have we gained any thing for science ? Noth- ing at all. It cannot possibly be lifted above the level of absolutely groundless speculation. It is not history. When referred to it, the title " Planetary History " is a misnomer. Sup- pose we drift with this theory thus far, is it at all satisfactory ? Whence the star dust ? We want a history of the cosmical matter. Carry us to the beginning. Let us reach the source of the historic stream. 138 THE MODERN GENESIS. But, really, this nebular theory is not a plan- etary history. It is not a history of matter. It is destitute of all the elements of history. It is a congeries of stupendous assumptions, and it disregards at every step the simplest, plainest, and most thoroughly established facts and laws of material nature. Who can tell whether the primitive state of matter was gas- eous or not ? Is it not as easy to account for terrestrial changes on other suppositions as on that ? But for the purpose of giving coun- tenance to the theory of ring formations it would probably never have been mentioned. For the nebular theory the gaseous condition is necessary. There must be a gaseous con- dition of the cosmical matter, according to one form of the theory, so as to allow of condensa tion by the force of gravity, and the condensa tion by this force is supposed to have evolved the inconceivable heat. Thus says HELMHOLTZ; "When the nebu- lous chaos first separated itself from other fixed- star masses, it must not only have contained all kinds of matter which was to constitute the future planetary system, but also, in ac- cordance with our new law, (Helmholtz here Densities Continued. 139 refers to the " Principle of the conservation of force,") " the whole store of force which at one time must unfold therein its wealth of ac- tion. Indeed, in this respect an immense dower was bestowed, in the shape of the general attrac- tion of all the particles for each other. This force, which on the earth exerts itself as grav- ity, acts in the heavenly space as gravitation. As terrestrial gravity, when it draws a weight downward, performs work and generates vis viva, so also the heavenly bodies do the same thing when they draw two portions of matter from distant regions of space toward each other. The chemical forces must also have been present, ready to act ; but as these can only come into operation by the most intimate contact of the different masses, condensation must have taken place before the play of chem- ical forces began. " Whether a still further supply of force, in the shape of heat, was present at the com- mencement, we do not know. At all events, by the law of the equivalence of heat and work W6 find in the mechanical forces, exist- ing at the time to which we refer, such a rich source of heat and light, that there is no 140 THE MODERN GENESIS. necessity whatever to take refuge in the idea of a store of these forces originally existing. "When, through condensation of the masses, their particles came into collision and clung to each other, the vis viva of their motion would be thereby annihilated, and must ap- pear as heat. " Already, in old theories, it has been calcu- lated that cosmical masses must generate heat by their collision, but it was far from any body's thought to make even a guess at the amount of heat to be generated in this way. At present we can give definite numerical val- ues with certainty." After stating the problem and the method of solution, Helmholtz continues : " The result of this calculation is, that only about the four hundred and fifty-fourth part of the original mechanical force remains as such, and that the remainder, converted into heat, would be suf- ficient to raise "a mass of water equal to the sun and planets taken together, not less than twenty-eight millions of degrees of the centi- grade scale." TYNDALL only expresses'the same meaning in another form of words when he says : " The Densities Continued. 1 4 1 potential energy of gravitation was the orig- inal form of all the energy in the universe." We see, in the light of these quotations, how necessary to this form of the nebular theory the assumption of the original gaseity of matter is. If the cosmical matter was of very great tenuity so great, indeed, that chemical forces could have no play then there could be condensation ; and, through condensation, vis viva or living force, or me- chanical force ; and, through the expenditure of the vis viva, heat ; enough heat, indeed, to raise a body of water equal to the mass of all the bodies in the solar system to a temper- ature of twenty-eight million degrees centi- grade. Two things the great philosopher of Bonn did not explain. He did not explain how matter could reach such tenuity without heat, and he did not explain what effect the developed heat would have on the density of the matter. He also speaks of the " nebular chaos," as separating itself from the other fixed-star masses," but leaves us entirely in the dark as to the mode of the separation. Certainly, if it is the behoof of science to show how planets 142 THE MODERN GENESIS. were separated from the " nebular chaos" it must be equally its behoof to show how the " nebular chaos " was separated from " the other fixed-star masses." That form of the nebular theory advocated by WINCHELL, STERRY HUNT, and others, also assumes the existence of matter originally in the condition of a gas of great tenuity, but in this case the gaseity is the result of incon- ceivably high heat. To this we shall have oc- casion to refer hereafter, and only mention it now to show that the gaseous condition of the cosmical matter is alike necessary to both forms of the nebular theory ; and also to re- mark that grave difficulties invest that form of the theory enunciated by Helmholtz which are avoided by Winchell, and it is therefore that we devote our attention chiefly to the theory as set forth by the latter as the more plausible theory. Planetary History. 143 CHAPTER IX. PLANETARY HISTORY. A magnificent picture Progressive changes in structure Discussion Structure of the earth The interior fires Hop- kins's theory The lunar stage Sir Charles Lyell Experi- ments of Mr. Daniels with molten metals. THE nebular theory, as a history of matter, follows the planetary masses into their separate and individual history. Cast off from the cosmical mass while yet inconceivably hot, they were self-luminous gaseous bodies. They could not at first be regarded as analogous to our sun. They would have to pass through a number of stages before they would reach the solar stage. But they contracted, and their axial rotation was accelerated and the satellite masses thrown off, as the planetary masses had been thrown off before. Thus the celestial fires were multiplied. Cosmical original, pri- mary planetary masses, and secondary planet- ary masses were glowing with their own na- tive heat together in the firmament. 144 THE MODERN GENESIS. But they came in time to be suns. Then they expired as suns, and the Saturnian stage came on. Just where, in the history, the tem- perature became such as to allow of chemical combinations, we are not informed. Perhaps this information is denied us for the purpose of leaving room for a healthful play of the imagination. It is, however, assumed that chemical com- bination began at the surface, because it was here that the cooling was most rapid. Cer- tainly we can imagine that it must have been very cold at the surface, or just outside of it. When chemical action began, and compounds were formed at the surface or in the higher re- gions, the compounds began immediately to fall toward the center of the mass. But they could not go far before they would meet a heat of dissociation, and their course would be arrested. More and more rapidly this process went on, and the cooling and contracting were accelerated. In process of time the cooling was carried to that extent that the elements, which were freely intermixed, sought chemical association, and combination generally took place throughout the mass. Planetary History. 145 Says Dr. Hunt : " So long as the gaseous condition of the earth lasted we may suppose the whole mass to have been homogeneous ; but when the temperature became so reduced that the existence of chemical compounds at the center became possible, those which were most stable at the elevated temperature then, prevailing would be first formed. Thus, for example, while the compounds of oxygen with mercury, or even with hydrogen, could not exist, oxides of silicon, aluminum, calcium, magnesium, and iron might be formed and condensed in a liquid form at the center of the globe. By progressive cooling, still other elements would be removed from the gaseous mass which would form the atmosphere of the non-gaseous nucleus." Chemistry of the Earth. Having an atmosphere thus theoretically provided for, an atmosphere of uncombined gases, and a central liquid nucleus, we are nat- urally led to the contemplation of the chem- ical combination of oxygen and hydrogen, and the beginning of a period of aqueous conflict with the interior heat. Winchell anticipates us here, as follows : " During a cosmic period 10 146 THE MODERN GENESIS. the clouds accumulate, slowly shutting out the light of the sun, and copiously discharg- ing their rains toward the planet. The rains, penetrating the lower strata of the atmos- phere, are converted to vapor, and returned to the clouds, to be again condensed and pre- cipitated. Every ascending particle of vapor carries off a portion of heat from the atmos- phere, and promotes the cooling of the planet. But cosmic changes are slow, and ages must elapse while a tempest rages in mid air, which is quite unfelt upon the surface of the planet, save as the vivid lightnings shed a violet gleam over the arid surface, or the rolling thunders mark the time of the tempest's march. Grad- ually the line of conflict settles toward the heated crust. At length the rain strikes the crust. Then, after a period of increased ex- citement in the elements, a universal ocean begins to accumulate a boiling, steaming, turbid ocean. After a further lapse of ages the cooling and accumulating waters lead to signs of exhaustion in the clouds. Light fil- ters feebly through, and the lowest organisms appear in the sea. Then the clouds break, and the full sunlight and peaceful elements Planetary History. 147 are the signal for advancing grades of organ- ization." This is history. That primitive impulse which originated the grand rotation has devel oped multiform energies, and that cosmical matter, whose tenuity was so great that several cubic miles would weigh less than a single grain, lies before us in massive rocks, underly- ing a universal ocean, surrounded by an at- mosphere fitted to sustain some forms of organization. , Let us follow over this historical track, and try its credibility. First of all we ask, What authority have we in experimental science for the assumption that an inconceivably high temperature could be maintained in a cosmical mass of dissociated elements ? What is temperature ? Heat is simply ther- mal activity or a form of motion, which exhib- its effects which are known as thermal. Tem- perature is the degree of that activity. Now we have no means of knowing what is the nor- mal thermal state. But we know that there are certain laws of thermal evolution. We 148 THE MODERN GENESIS. know that certain substances, when brought into contact at certain temperatures, will im- mediately rush into chemical combination. We know that the chemical combination, when it is effected, occasions the exhibition of heat. But at other temperatures we know that the same elements might remain imtermixed for long periods of time without combining, and that so long as they thus remained no heat will result from their intermixture. We know, also, that these same elements might be put into motion and brought suddenly into col- lision while moving in opposite directions, and that their mass motion would be converted into that molecular motion which we call heat. But we do not know that the elements can all exist in a vaporous or gaseous condition without heat. And we do not know of any mode of producing such a heat as could effect so complete a sublimation of the elements as the nebular theory supposes to have existed. If these elements were put into the gaseous state by heat and intermixed, we may con- ceive of their remaining together in that state so long as the heat is maintained, but the heat must, in some way, be generated. Planetary History. 149 But in the hypothetical cosmical mass there is no generation of heat. No rational account of its origin is given. There is no chemical combination. It is too hot for that. There- fore chemical combination cannot account for the heat. It is not the contraction of the cos- mical mass, for the contraction is the result of cooling. Whence the inconceivable heat of the original cosmical mass ? What kind of activity could exist among elements chem- ically dissociated, and incapable of chemical combination, the manifestation of which would be a continued thermal state of inconceivably high temperature? We have sought in the writings of the ad- vocates of the nebular theory for some rational answer to these questions, and we have sought in vain. We have read with special interest " The Chemistry of the Earth." Surely, we said, we shall find a clew to the origin of the nebular temperature. So distinguished a physicist as Dr. Sterry Hunt will not pass this point unnoticed. But he does. He says: ' The nebulous matter is conceived to be so intensely heated as to be in the state of true gas or vapor." That is all the light we 150 THE MODERN GENESIS. get on the subject, and that is just no light at all. " The nebulous matter is conceived to be so intensely heated " by what? When we look at the rotation of planets in orbits we behold movements, for the origin of which this nebular theory professes to give us an historical account, pointing us to an axial rotation of a hypothet- ical cosmical mass as the original of the orbital planetary rotation. When we turn our thoughts to this hypo- thetical cosmical -mass, and consider its axial rotation, we behold a movement for which the nebular theory professes to render an account, assigning as its cause the cooling and contract- ing of the cosmical matter. But this " cooling of the matter " is simply the subsidence of molecular movements in the matter. Heat is molecular activity. Cold is molecular inac- tivity or rest. In this chain of causes we have now reached the most important of all. Here is the " primitive impulse which originated the grand rotation." It must be here, and we wish to know what it is. Here is motion, molecular motion, more in- tense than any that is known in our day. It Planetary History. 151 is more intense than that which exists in the sun. What is the cause of this motion ? And how is this motion maintained ? And why is this molecular motion supposed to subside first at the surface, where there is nothing to react upon it ? In our simplicity we have supposed that all motion implied the previous existence and the application of force. Molecular motion is not an exception to the rule, so far as we know. Then we are justified in demanding a cause, in some mentionable force, for the hypothet- ical high heat of the original cosmical matter. Here the nebular theory seems to us to leave the cosmical mass in a situation somewhat similar to that of Deacon Homespun's world. His world was as flat as a pancake. His world rested on rocks. These rocks rested on rocks. And those rocks rested on rocks ; and, finally, "Well, you simpleton, it's rocks all the way down." And thus the stability of the world is accounted for. So, according to the nebular theory, we have a world in motion, and its motions are accounted for by referring them to an axial rotation of a cosmical mass. Then this axial rotation must 152 THE MODERN GENESIS. be accounted for. And the theory assigns, as its cause, the cooling and contracting of the mass, which " Is conceived to be so intensely heated as to be in the state of a true gas or vapor." Here, in this indescribable heat, is the most stupendous motion of all, the molec- ular motion, which was capable of tearing in pieces the aggregate matter of the solar sys- tem, dissociating the elements, and giving to the mass so great tenuity that three cubic miles of the stuff should be less than one grain in weight, and here the nebular theory leaves us uninformed as to the cause of this stupendous activity. " Rocks all the way down." Just so, deacon ; that is just as scientific as to say, u Motion all the -way back" We put your cos- mical theory and this nebular theory in the same category as equally rational. But we must follow the track of this cos- mical history. If it does not inform us how the motion began, it does tell us something of what follows. Let us pass those periods dur- ing which the planetary masses were detached as gaseous bodies ; let us hasten on, not stop- ping even to glance at the gaseous satellites, Planetary History. 153 and let us not be delayed by the terrific ele- mental convulsions which took place when the elements awoke to the realization of their first love and rushed into each other's embrace, and let us look at the subdued, tempered, peopled earth, with its strong rocky crust, its broad oceans, and its vital atmosphere envel- oping all. There have been mighty upheav- als. Great mountain ranges have been built up, ocean beds have been depressed, the igne- ous rocks have been exposed to winter's frosts and parched by summer suns ; pelted by tor- rents of acidulated rain, and worn by unre- strained hurricanes; and thus cracked, shiv- ered, corroded, crushed, the waters have swept the disintegrated ruins down into the ocean. Again and again this process of evolution, dis- integration, and transportation of rock material has been repeated. The terrestrial stage has already lasted un- told ages. Yet, even now, what the world was, is indicated to us by what it is. Within its crust is a globe of liquid fire. The crust itself is only a few miles in thickness. Here and there great openings afford to the curious a sight of the boiling hot elements. 154 THE MODERN GENESIS. These things prove what was the earth's former state. But all do not accept this inter- pretation of the facts of terrestrial history. Dr. Hunt says : " The effect of pressure upon materials like molten rocks would be such that solidification at a depth from the surface would take place at a temperature much high- er than that required for their solidification at the surface. Hence, in opposition to the no- tion of a congealed layer, like ice, resting upon the surface of the molten globe, Hopkins, and with him Scrope, supposes solidification to have commenced at the center of the liquid mass, and to have advanced toward the circumfer- ence." We shall not, therefore, be without excel- lent company if we venture to express a doubt that our earth has a superficial crust and an interior molten mass. We may be permitted the thought that we live on a globe which is chiefly solid, that the liquid portion is quite small in proportion to the whole mass, and that the portion that is molten with high heat is a still smaller portion than the lakes and seas that variegate the surface. Dr. Hunt further remarks : " Apart from Planetary History. 155 these considerations, however, many of the best modern physicists and geologists have found numerous reasons for rejecting the pop- ular notion which regards our globe as a liquid molten mass covered by a layer of twenty or thirty miles of solidified rock. The deduc- tions of Hopkins from the phenomena of pre- cession and nutation ; those of Pratt from the crushing force of immense mountain masses, like those of the Himalaya ; and those of Sir William Thompson from the tides, showing the great rigidity of the earth all unite to prove that the earth, if not solid to the center, must have a firm and solid crust several hun- dred miles in thickness. Under these con- ditions, if there still exist a liquid center, it must, so far as superficial phenomena are con- cerned, be as inert as if it were not. We are thus prepared to accept the conclusions to which the line of argument leads us, and ad- mit that our globe solidified from the center." Chemistry of the Rarth. If the earth solidified from the center, then it is solid at the center. How far outwardly from the center does the solidification extend ? Evidently it must extend outwardly to the 156 THE MODERN GENESIS. surface, or we must suppose a solid globe within a molten envelope, which itself is in- closed within a solid shell. It would be a curious problem to determine what would be the result of such an arrangement as this. But it would seem that if the center, and from the center outward for any great distance, is solid, there is nothing to justify the conclusion that an intermediate, continuous, concentric chamber, so to speak, is filled with matter in original molten condition. The nebular theory, as set forth by Win- chell, finds all its contractions arising from the cooling of the mass. The internal fires are inclosed within the rocky crust. Very grad- ually the heat is being radiated, because it is only slowly conducted to the surface. But the crust is thickening constantly by the cool- ing of that portion of the interior mass which is in contact with the crust. The present condition of the moon is sup- posed to be such as that toward which the earth is progressing. There the theory be- holds a world whose interior fires have quite burned out ; whose oceans, and seas, and at- mosphere have been sucked up by the rocks ; Planetary History. 157 a world which is now " a fossil world, an an- cient cinder, suspended in the heavens ; once the seat of all the varied and intense activities which now characterize the surface of our earth, but in the present period a realm of silence and stagnation. " And the same process of refrigeration which has brought the moon to a state of desolation and solitude is now going on within and upon the earth. Thus the history runs, from the in- conceivable heat and the attenuated gaseous condition, to the denser vapor; 'then to the liquid; then to the solid, (but still the white hot solid ;) afterward to the red hot ; afterward to the blackened, igneous rock, and on to the cooled exterior, and the molten, fervid inte- rior, and the end, is to be a cold, cheerless desolation. How much of this theory owes its exist- ence to the fact that we know of the exist- ence of subterranean fires, and lakes of liquid lava? From molten lava to the assumption of an original molten earth is not a very ex- travagant flight of the imagination ; and from the molten earth to the igneous nebular con- dition is not a very difficult flight, especially 158 THE MODERN GENESIS. if one may rest the wings of his fancy on real nebula in the heavens. But a molten earth is an assumed point. Though deemed one of the most important of the data, it is only an assumption. Take this away, and what becomes of the theory? We are quite sure that this molten earth is really a necessity to the theory. What else but the internal fires prevents the rocks from absorbing the terrestrial oceans and the terrestrial atmos- phere ? And yet this molten earth is taken away and rendered absolutely unavailable by the computations and reasonings of " many of the best physicists and geologists," and they do reject this " popular notion " of a " liquid, molten mass surrounded by a layer of twenty or thirty miles of solidified rock." These physicists are at least some of them are men who accept the Nebular Hypothesis. Yet they find that the present earth is not a molten globe, enveloped by a thin crust, but that it must be considered as almost entirely solid. And this they do mathematically, and not with loose generalizations. The question with them is not, " What was Planetary History. 159 the earth once ? " but " What is it now? " To this question they make answer, and the an- swer is, " The earth is so nearly solid, that if there be any portion near the center that is molten, it is, so far as external phenomena are concerned, as inert as if it were not." And then Dr. Hunt comes in with his chemical data, and shows that this condition of central solidity is not inconsistent with the law of so- lidification of metals and metallic compounds under pressure. We are warranted, therefore, not only in the conclusion that the fluidity of the central earth is not proven, but that, even if the whole mass were once fluid from the effect of heat, it is not fluid now. And if not fluid now, then all the theoretic history, based on the assumption of its present fluidity, fails with the assumption. Sir CHARLES LYELL presents another view of the subject. He says : " The conditions of the problem are wholly altered when we rea- son about a fluid nucleus, as we must do if it be assumed that the heat augments from the surface to the interior according to the rate observed in mines. For when the heat of the lower portion of a fluid is increased, a circula- 160 THE MODERN GENESIS. tion begins throughout the mass by the as- cent of hotter and the descent of colder cur- rents. And this circulation, which is quite distinct from the mode in which heat is prop- agated through solid bodies, must evidently occur in the supposed central ocean, if the law of fluids and of heat are the same there as upon the surface. In Mr. Daniel's experi- ments for obtaining a measure of the heat of bodies at their point of fusion, he invariably found that it was impossible to raise the heat of a large crucible of melted iron, gold, or sil- ver a single degree beyond the melting point so long as a bar of the respective metals was kept immersed in the fluid portions. So, in regard to other substances, however great the quantities fused, their temperatures could not be raised while any solid pieces immersed in them remained unmelted, every accession of heat being instantly absorbed during their liquefaction. These results are, in fact, no more than the extension of a principle pre- viously established, that so long as a fragment of ice remains in water we cannot raise the temperature of the water above thirty-two de- grees Fahrenheit. There must be a continual Planetary History. 161 tendency toward a uniform heat, and until this were accomplished by the interchange of por- tions of fluid of different densities the surface could not begin to consolidate. Nor on the hypothesis of primitive fluidity can we con- ceive any crust to have been formed until the whole planet had cooled down to about the temperature of incipient fusion." Principles of Geology. Lyell also refers to the opinions of M. PoiS- SON, as set forth in a memoir to the Academy of Sciences in 1837, on ^he solid parts of the globe, and adds : " In this memoir he contro- verts the doctrine of the high temperature of a central fluid on similar grounds to those above stated. He imagines that if the earth ever passed from a liquid to a solid state by the radiation of heat, the central nucleus must have begun to cool and consolidate first." One consideration more occurs to our mind as worthy of record on this subject. Assum- ing the fluidity of the earth, and the presence of the elements now present in it, we cannot conceive how the formation of a superficial crust was possible. First. Because of the agitation of the surf ace 11 162 THE MODERN GENESIS. by the process of convection, to which our at- tention has been called by Lyell. That tre- mendous agitation of the primitive ocean, to which Winchell refers, would have been less than a ripple caused by the gentlest zephyr, in comparison with the spouting, out-bursting exhibitions of the heart-force from within the mass of molten matter. And this activity must have continued until the whole mass came near the temperature of solidification. Secondly. Because of the effect which must have been exrted by the tides. We speak not now of the ocean tides, but of tides in the molten mass itself. It would seem that these must have been of far greater magnitude than the ocean tides now are, and that they must have broken up the incipient crust, which, falling into the mass and subjected to the con- vulsing agencies of the convectional process, would be broken, crushed, and fused. So we are brought again to the same conclusion, that if the earth were once molten it could* not, by the simple process of cooling, become solid superficially while remaining fluid internally from retained heat. Terrestrial Changes. 163 CHAPTER X. TERRESTRIAL CHANGES. Earthquakes and volcanoes Molten interior earth Thick- ness of the earth's crust Subterranean lakes of fire Habit- ual volcanic action. DO the advocates of the nebular theory ask, " If the interior of the earth be not in a molten condition, how can we account for earthquakes and volcanoes?" We may reply with another question, " If the interior of the earth be in a molten condition, with a thin su- perficial crust, how can we account for earth- quakes and volcanoes?" By the internal tides ? Then volcanic erup- tions must be greatest in the line of the moon's path, and they must occur regularly twice every day the year round. Moreover, as in the ocean, there are spring tides, caused by the joint influence of the sun and moon ; and neap tides, arising from their quadrature ; so, also, in the interior molten mass there must be spring tides and neap tides, and we should see 164 THE MODERN GENESIS. their effects in increased volcanic activity. But we do not see any of the manifestations of such interior tides. The volcanoes are not situated in any such zone as this hypothesis would require, and their activity is not at all correspondent to the supposition. But we have also shown that such internal tides would break the crust itself in pieces, and that its permanent formation would be impos- sible till the interior mass had cooled off to near the temperature of solidification. Then there would remain no interior molten earth, to account for earthquakes and volcanoes. Still, we must not ignore the fact that many geologists do maintain the theory of a central molten earth, and that they by it undertake to account for earthquakes and volcanoes. Nearly all the elementary works on physical geography and on geology designed for the use of schools, and nearly all the popular trea- tises on these subjects, teach the theory of an internal molten condition of the earth, and sometimes the volcanic openings are described as the " safety-valves of the globe." Perhaps we should gratefully contemplate these singular provisions for the world's safety, Terrestrial Changes. 165 and just here lay down our pen. But we choose to continue our inquiry. We open one of the elementary text-books of the day, and find that " it is believed by most geologists that the interior of the earth is in a molten state, that the whole earth has been in that condition, and that the crust or solid portion is not more than fifty or one hundred miles thick." Tennys Geology. The grounds of this belief of geologists are various, but the most plausible are the ob- served increase of temperature in mines, and the similar increase of the temperature of the waters of artesian wells, as we go down into the greater depths. " The sun does not affect the temperature of the earth below the depth of one hundred feet. But for every forty-five or fifty feet of descent below that point the temperature rises about one degree Fahrenheit. If the increase go on at that rate, a point would soon be reached where the heat is sufficient to melt all known substances." Tenny. Our readers can make their own estimates. Every fifty feet of depth below the first one hundred feet is equal to one degree of heat. i66 THE MODERN GENESIS. Now iron melts at 2,786 degrees ; gold, at 2,590 degrees ; zinc, at 680 degrees ; lead, at 612 degrees; bismuth, at 540 degrees; sodium, at 200 degrees, etc. How far down must we go to find a heat sufficient to fuse iron ? Ev- idently we must go 100+50x2,786 degrees= 139,400 feet, and that is 26.4 miles. But Sir Isaac Newton has shown that when a metal of low fusibility is mixed with one of high fusibility, the two metals will melt at a lower temperature than either of them would melt at alone. By combining bismuth, lead, and tin, he produced an alloy which melted below two hundred and twelve degrees. We know that silica, and soda, and potash are abundant in the earth, and though silica withstands the heat of the blow-pipe, yet we know that it readily fuses in the glass manu- facturer's furnace when mixed with lime, soda, and potash. We might extend our list of substances, each of which acts as a flux to others, making them less refractory when mixed together. Now we are contemplating a mass of matter in which all the elements are intermixed. We are not at liberty to say the temperature must Terrestrial Changes. 167 be raised to the point at which platinum, or silica, or alumina would separately fuse before the mass of mixed elements will be found fused. We shall probably be justified in as- suming that at the fusing temperature of iron or gold, the mass of the material of the earth would be fused. Then we should be brought also to the conclusion that the crust of the earth cannot be more than 26.4 miles thick. Our geologists are apparently startled by their own figures. At least they are consider- ate of the nerves of the common people, who have no idea how near they are to the great lake of liquid fire. An egg shell is of great thickness when compared with this supposi- titious terrestrial shell. But the geologist says the thickness is fifty or one hundred miles, as if fifty were almost one hundred, leaving a slight margin to meet the contingency of any minute error that might have slipped into the calculation. Before we leave this subject we would re- mark that the data on which these estimates of the rate of increase of heat are based are too meager to justify a general conclusion. That there is an increase of temperature as we i68 THE MODERN GENESIS. descend into mines is true, and that there is an increase of temperature in water from lower depths is also true ; but physicists are by no means agreed as to its cause. It may be chemical ; it may be mechanical ; it may be proximity to subterranean fires ; and yet those fires may be local. The deepest well of which we know is that at Sperenburg, near Berlin, Prussia. That well, it is said, does not indicate a uniform increase of temperature as we descend. The well is four thousand one hundred and ninety- four feet deep. At the depth of one hundred feet the temperature was 57.2 degrees ; at one thousand feet it was 73.8 degrees, an increase of one degree for every 54.2 feet ; at the depth of two thousand feet the temperature was 91.4 degrees, an increase of one degree for every 56.8 feet ; at the depth of three thousand feet the temperature was 109.4 degrees, an increase of one for every 55.5 feet; and at the depth of four thousand feet the temperature was 1 1 8.6 degrees, an increase of one degree for every 108 feet. It would seem, then, that there is no certain rate of increase of heat as we descend into the Terrestrial Changes. 169 earth. It is possible that the next thousand feet would show still less increase. It may be that there is in the solid earth, to the depth of four or five miles, sufficient chemical activity to produce a sensible increase of temperature. It may be that magnetic or electrical condi- tions exist, which, if known, would elucidate all. All we certainly know is that the increase of temperature is not uniform, nor uniformly accelerated, as we have reason to expect it to be, on the supposition that the whole globe is molten matter, except a thin crust. We open another elementary text-book of geology, and we read : " The appreciable or ponderable crust of the earth, however, calcu- lating from the astronomical phenomena of precession and nutation, cannot be less than a fourth or a fifth of the earth's radius ; that is, it cannot be much less than eight hundred miles." Wells s First Prin. Geol. The precession of the equinoxes is caused by the attraction of the sun and moon on the equatorial protuberances of the earth. It is evident that the amount of disturbance which would result from these attractions would not 170 THE MODERN GENESIS. be the same if the earth were fluid that they would if the earth were wholly or chiefly solid. Mr. Hopkins, after carefully estimating the effects of these attractions on the different sup- positions, says : " Upon the whole, then, we may venture to assert that the minimum thick- ness of the crust of the globe, which can be deemed consistent with the observed amount of precession, cannot be less than one fourth or one fifth of the earth's radius." Pratt arrived at the same conclusion from an estimation of the crushing force of certain great mountain masses, and Sir William Thompson reached the same conclusion from a consideration of the tides. If, then, we have a central molten earth, we are obliged to con- ceive of it as separated from the surface by a rocky crust of from eight hundred to one thou- sand miles in thickness. We now return to the question, " If the in- terior of the earth be a molten mass, enveloped by a thin shell, how can we account for earth- quakes and volcanoes?" Do the phenomena attendant upon earthquakes and volcanoes in- dicate a molten condition of the interior of the earth? They do indicate a molten condition Terrestrial Changes. 171 of a portion of the earth. But is it a central portion ? Is it a portion whose perpendicular distance from the point of surface exhibition must be reckoned at a score or two score, or by even hundreds of miles ? Do they indi- cate a common origin, that is, are the phe- nomena such as could proceed from a com- mon source ? Does not each indicate an or- igin, respectively, in a local subterranean chamber? How extensive the subterranean lakes of fire are we may never know ; yet, compared with the globe itself, they are prob- ably small. How, otherwise, can we account for the fact that volcanoes are so widely separated and so local ? The whole world is not volcanic. But there are districts which are now volcanic and have been for ages, and there are other districts which were once volcanic, and are now, and have been for ages, free from volcanic action. If volcanoes originated in the central 'part of the earth, then, whatever be the nature of the forces which produced them, and whatever be the method of their generation, we should expect to find them more generally distributed than they are, unless we refer them to internal tides. \j2 THE MODERN GENESIS. Again, assuming that the earth's crust is fifty miles thick, then what prevents the slen- der chimneys of the volcanoes becoming clogged and utterly stopped by the ascending column of liquid rocks being cooled and solid- ified? We do soberly question the possibility of keeping the world's safety-valves open if the molten matter has to be lifted a perpen- dicular height of fifty miles through the small chimney that a volcano offers for its passage. But we are compelled to contemplate a still longer chimney by the calculations of Hop- kins. It cannot be less than eight hundred miles. Now, while it would tax our credulity to admit the existence of any forces in the central chambers of the earth which could lift a perpendicular column of lava of eight hundred miles, we are even less ready to be- lieve that such a long column could possibly maintain its liquidity. But there is great difficulty in accounting for the ejection of the lava from so great a depth, and especially from so vast a chamber as the interior of the earth must be if its crust is only fifty, or even one hundred miles thick. We can conceive of a comparatively small Terrestrial Changes. 173 subterranean chamber being formed by the changes of the constituent portions of the rocks effected by chemical action ; we can conceive of the evolution of heat, the liber- ation of gases, the melting of rocks, the gener- ation of steam, and the consequent exertion of immense force upon the surrounding mass. And conceiving of the crust above the sup- posed chamber as being comparatively thin, we can conceive of these forces being intens- ified to such a degree that they will effect a rupture of the rocks and produce an earth- quake or a volcano, or both. But if we refer the earthquake to the same class of forces, and conceive of them as being generated below the crust, whether we suppose that crust to be fifty miles or eight hundred miles thick, then we have an entirely different condition of things. If there be any space at all between the liquid central mass and the solid crust, we shall find it closed on the sides where tides are formed, and open on the sides in quadra- ture thereto. If the forces that are gener- ated are greater than the upward tidal press- ure, they will more than support the crust provided that they can be confined and 174 THE MODERN GENESIS. will cause a succession of earthquakes as the earth revolves on its axis, the strain being con- stantly transferred to that portion which is in quadrature with the tide. But in any event, if the forces which are supposed to cause the earthquake are gases or steam, and if they be supposed to be generated at the surface of the liquid mass, they will have an immense area over which they must extend before they can exert any lifting or disrupting power, and whatever power they exert must be almost equally exerted over that immense area. We do not see how this class of agencies steam, gas, etc. can ever produce a volcanic eruption ; that is, how they could, by their pressure on the surface of the molten mass, cause a column of it to ascend through one of these volcanic chimneys, un- less it should be in those regions where the internal tides press against the crust ; and when we consider how brief a time the tide can last at any given point, we shall see that there would not be time for the upward flow to reach the surface of the earth before the open space would be brought beneath the chimney. Terrestrial Changes. 175 But we are unable to perceive how there could ever be any considerable accumulation of gas or steam beneath the crust under the conditions that are known to exist, for the di- urnal rotation would be constantly bringing the open space under the chimneys, and the forces would be constantly escaping. A steam boiler with a hundred leaks, though they were no larger than a hair, would be regarded as an inefficient motor agency. We cannot see how the escape of the forces could be avoided. Every fracture of the crust, as well as every old opening, would allow them to escape. How, then, could they accumulate so as to push up even a fifty-mile column of molten rock, and display all the activities of actual eruptions. Volcanic energies are known to increase in the same locality for days and weeks, and then to culminate in grand eruptions, fol- lowed by seasons of quiet. How can such local paroxysms be reconciled with the theory of an internal liquid mass and an outer crust ? But having proceeded thus far on the pre- sumption that there might be a generation of steam in the interior of the earth, we now call 176 THE MODERN GENESIS. in question the possibility of such generation. Winchell says : " Consider that in the present condition of our globe the water and air must be unable to penetrate more than one fiftieth the distance to the earth's center. Percolat- ing downward through the rocks, the water soon reaches a temperature which dissipates it into vapor, and returns it toward the surface to be recondensed." One fiftieth the distance to the earth's cen- ter is about eighty miles. That is thirty miles further than many geologists allow for the thickness of the earth's crust. Let us make an estimate on the assumption that the tem- perature increases one degree for every fifty feet of descent. At the depth of one hundred feet the temperature averages about fifty-eight degrees. At two hundred and twelve degrees water is converted to vapor. At four hundred and fifty-six degrees steam has a tension equal to thirty atmospheres. At this tension is it likely to penetrate farther into the rocky depths ? Let us suppose that at four hundred and fifty-six degrees of temperature the de- scent of water will be arrested. What depth has it reached? 456 58 = 398. And Terrestrial Changes. 177 398x5o feet=i9,900 feet. Add 100 feet, at which depth the average temperature is about 58 degrees, and we have 20,000 feet. And 20,000 feet are only about 3.8 miles. One has only to look at these figures to see how loosely a theorist will sometimes express himself on a scientific subject. Certainly, if we grant the premises to wit, that for every fifty feet of descent the temper- ature rises one degree we must conclude that water will be converted into steam at the depth of seven thousand eight hundred feet, and that at the depth of 3.8 miles the steam, if it could penetrate so far, would have a ten- sion of thirty atmospheres. We conclude that such a temperature would exclude it if the reasoning of Winchell on this point be correct and that water, there- fore, could not penetrate the earth below that depth. But this, instead of being one fiftieth is only about one thousandth part of the dis- tance to the center of the earth. But the heat which is supposed to exist below the earth's crust is many times as great as that which pro- duces steam of the tension of thirty atmos- pheres. It is a heat of fusion for all known 12 178 THE MODERN GENESIS. substances. And before reaching the fusing point the rocks must be conceived to be at red heat. Water certainly would not " percolate " long through red-hot rocks. How, then, can steam ever be generated below the earth's crust ? If the volcanoes have their origin in the central molten globe, how can we account for the differ- ent habitual behavior of different volcanoes ? There is, in many of the existing volcanoes, what may be called characteristic behavior? Stromboli, which so long ago as the time of Homer received honorable mention, is a kind of restless, fussy volcano, always active, but never remarkably so. Ashes and vapor as- cend out of its crater daily, and its eruptions occur periodically at intervals of three to five months. Rancagua, in Chili, is another active, but moderate, volcano. Vesuvius has long seasons of great tranquillity, followed by tre- mendous subterranean convulsions and over- whelming discharges of lava and ashes. Etna, in these respects, resembles Vesuvius. Hecla is a volcano of stupendous energy. It some- times rests for a period of years ; then it Terrestrial Changes. 179 gathers its forces, wraps itself in flames, and energizes marvelously for years, until it seems to be exhausted with the fury of its own rage, and it settles down again into quiet. Mauna Loa has the singular habit of running over in a very quiet manner, and sending great rivers of liquid lava to the sea with very little dis- turbance to the land. While other volcanoes usually announce the approach of their great eruptions by great quakings and subterranean mutterings, Mauna Loa scarcely sounds a note of warning. These are marked distinctive characteristics of these different volcanoes. They indicate differences in their origin. If we refer them to the different constituents of the rocks from which they arise, we have an assigned cause, which is in harmony with their behavior. If we refer them to the central liquid earth, as the common source of all volcanoes, we are un- able to reconcile their behavior with our sup- position. The volcanic district of which Mauna Loa is the center is the theater of volcanic ac- tion so singular that we cannot forbear to ex- tend our examination of it, with direct refer- ence to the theories we are discussing. i8o THE MODERN GENESIS. Hawaii is the largest of the Sandwich Isl- ands. Mauna Loa is a volcanic mountain in the southern part of the island. It is about fourteen thousand feet high. Since it became known to the civilized world a number of erup- tions have occurred. In 1843, during an erup- tion, a rent twenty-five miles long was made in the mountain. In 1852 another erup- tion took place, during which the liquid lava rose to near the top of the crater and flowed out at a small opening. . Meanwhile the press- ure of the mighty column caused a break of great magnitude, about four thousand feet low- er down, and here it threw up a jet of lava one thousand feet in diameter to a height of seven hundred feet. Another eruption in 1855 con- tinued during several months to send forth a river of lava, which extended to a distance of sixty-five miles, and was three to five miles wide. Again, in 1859, on the night of January 23, without warning, it vomited forth its liquid fires so abundantly that they ran twenty-five miles during the night. Jets of liquid fire were projected upward to the height of one thousand five hundred feet. Reaching the sea, at a distance of forty miles, the volcanic Terrestrial Changes, 181 river extended two miles into the water. All these eruptions have been attended with breaks in the mountain some distance below the sum- mit, so great was the force exerted by the higher column of molten lava on the side of the mountain. About sixteen miles from Mauna Loa, at an elevation of only four thousand feet above the level of the sea, is Kilauea, the most re- markable crater in the world. Kilauea is an immense depression, one thousand feet deep, three miles long, and about one mile wide. In the bottom of this immense crater are smaller craters of different elevations, in which the volcanic action is always to be seen in pools and lakes of lava. Standing on the brink of the chasm the spectator beholds the lava in one of these pools rising to the height of one hundred and fifty feet or more, while in another it may descend one hundred feet or more. Perhaps one of them will be spouting furiously while another will be quiet and placid. This great crater has also sent forth its rivers of molten rocks. Mr. Ellis visited it in 1823, and he describes two of the lava pools at the bottom, the largest of which he says 1 82 THE MODERN GENESIS. was one thousand one hundred and ninety yards long. During that year there was an eruption from Kilauea of such magnitude that the lava stream, where it entered the sea, was four or five miles wide. Another eruption took place in 1832, and another in 1840. Of this eruption Mr. Coan, an American missionary to the Sandwich Isl- anders, gives an interesting description : " Imagine to yourself a river of fused mate- rials of the breadth and depth of Niagara, and of a gory red, falling in one emblazoned sheet, one raging torrent, into the ocean ! The at- mosphere in all directions was filled with ashes, spray, and gases, while the burning lava, as it fell into the water, was shivered into millions of minute particles, and, being thrown back into the air, fell in showers of sand on all the surrounding country. " The coast was extended into the sea a quarter of a mile. Three hills of scoria and sand were also formed in the sea, the lowest about two hundred and the highest about three hundred feet high. For three weeks this ter- rific river disgorged itself into the sea with lit- tle abatement. The waters were heated for Terrestrial Changes. 183 twenty miles along the coast, and multitudes of fishes were killed. The breadth of the stream where it fell into the sea is about half a mile, but inland it varies from one to four miles in width, conforming, like a river, to the face of the country over which it flowed. The depth varies from ten feet to two hundred, ac- cording to the inequalities over which it passed. The whole course of the stream, from Kilauea to the sea, is about forty miles." We have thus given, as briefly as possible, an account of these two most singular craters and their action. But the most remarkable fact is yet to be mentioned. That fact is that these two craters seem never to be in sympa- thy with each other. Mauna Loa may be send- ing forth a vast river of lava from a height of fourteen thousand feet, and Kilauea will repose as quietly as if no great event were transpiring. While the great river runs from Mauna Loa we look to see the larger and lower crater of Kilauea fill up with lava and run over. And we look for it the more confidently when we behold the pressure of the vast column of lava in Loa affecting great breaks in the mountain far down its sides. But we look in vain. And 1 84 THE MODERN GENESIS. we involuntarily ask, " Are these two craters, thus near each other, connected ? Are they both outlets of the same interior ocean ? " Why, then, does not the liquid lava rise equally in both ? How can a column fourteen thousand feet high exist in connection with an opening only four thousand feet high, and yet not flow out at that lower opening at all ? How is it that while a stream of lava flows from near that elevated summit, the pools of Kilauea only vibrate vertically or spout as they ordinarily do ? All fluids seek an equilibrium. This is not less true of iron and other metals when melted than it is of water. And we take advantage of this principle or law of fluids to convert pig- iron into castings of various forms. Were it not for this law, all cast forms would be impos- sible. Whenever, then, a molten liquid mass, of whatever element, rising in a duct, finds a lateral opening sufficient for its volume, it will follow the lateral outlet in preference to going higher. That it would do this in these Ha- waian craters if the chimneys were connected is evident from the fact that the very mountain mass of Loa is burst open by the immense Terrestrial Changes. 185 pressure, and the lava does make its escape several thousand feet below the summit at every eruption. Now let it be assumed that the huge duct leading from the central earth to Mauna Loa divides at some point in the depths, something as indicated in the follow- ing figure : We can conceive that in the formation of the volcano, in the upheaving of the mountain, the solid crust would be so broken as to afford two or more openings several miles apart, and that these openings should be in communica- tion with each other, and so long as these openings were on the same level, they would equally answer as outlets for the liquid lava 1 86 THE MODERN GENESIS. which should rise to the surface and seek an outlet. But it is insupposable that the molten mat- ter would follow one volcanic chimney only when there were two equally eligible ones meeting at a point far below the place of discharge. Rising in either, the law of equi- Jibrium would cause it to risej equally in the other. If, then, two craters, of unequal altitude, be connected with the same main chimney, we shall find the lower crater active, in all cases, before the higher one can be. But here is one crater which is fourteen thousand feet high, and another crater, only sixteen miles away, which is only four thousand feet high. And this lower crater always ex- hibits some degree of activity. Its lakes and pools of lava are always liquid and in motion, thus showing, that wherever the origin of their volcanic activity may be, between it and these pools and lakes the communication is constant, and the intermediate chimney is always filled with liquid lava. The rising and falling of the pools show that there is no impediment to the freedom of its vertical movements, and there- Terrestrial Changes. 187 fore, however long the column may be, it moves freely throughout its whole extent. There is nothing, then, to hinder the higher column from exerting the whole force of its pressure on the lower, if they be united at any point. How tremendous must that pressure be ! Moreover, the history of these two cra- ters shows that wherever the source of their respective streams of lava may be, the opening to the two craters are ample, for the outpour- ings have been immense. Those great rivers of lava, of which we have just given an ac- count, declare how ample were the openings through which they came from the depths. In view of these facts we venture the sug- gestion that these great craters cannot be con- nected at all. They have not a common or- igin. As two separate districts not remote from each other may be underlaid by one great coal field, as many different shafts may be sunk, and each district extensively under- mined and its treasures of coal brought to the surface, so we may conceive of the same char- acter of rocks to underlie vast areas, and the conditions necessary to chemical action therein to be gradually prepared by the forces that are i"88 THE MODERN GENESIS. ever operating among elements and masses ; then we shall have the chemical reactions, the evolution of heat, the increase of chemical ac- tion, and the melting of the rocks. If water be present in quantities more than sufficient to promote the chemical action, it may be con- verted into steam ; and if the heat be sufficient to fuse metals the steam must be superheated, and its expansive power would be such as to cause fractures in the walls of the concavity, which the steam and gases must immediately penetrate, thus extending the theater of chem- ical action. And thus we can conceive how the upper portion of the rocky structure may be lifted, and the active forces advanced, until an opening to the surface is effected. It would, perhaps, be presumptuous to say that this prob- ably is the mode in which volcanoes have orig- inated. But certainly this seems more nearly to satisfy the rational conditions of their for- mation than the theory of a central origin. And it may be remarked that if we find it impossi- ble to reconcile the action of one volcano to the theory of central origin if we can account for it on other principles then that central molten globe ceases to be a theoretical neces- Terrestrial Changes. 189 sity, and it vanishes out of cosmical history as one of a congeries of assumptions. The characteristic behavior of various volca- noes is equally against that theory which as- signs, as their cause, the constant contraction or shrinking of the earth's crust. There is another set of facts which we ought to take into account in this discussion. Vol- canic regions are generally near the sea or other body of water. Between the sea and that subterranean cavity in which the volcanic materials are prepared there is evidently some sort of communication, so that the waters per- colating through the rocks or following mi- nute channels furnish the moisture which is requisite for the production of chemical activ- ity and the supply of the steam force which is brought into play at the time of an eruption. It is known, also, that in volcanic districts sub- terranean lakes do exist, which are filled with fishes. Sometimes the separating walls are broken down, and the waters of such a lake are precipitated into the volcanic chamber, and the fish are thrown out at the crater during an eruption, the activity of which is enhanced by the waters. " So great a quantity of these fish 190 THE MODERN GENESIS. were ejected from the volcano of Imbabura in 1691, that fevers, which prevailed at the period, were attributed to the effluvia arising from the putrid animal matter." Lyell. Professor Ehrenberg has found that " vol- canic products abound with the flinty shells of minute microscopic animals." If this be true, it would imply that the lava was once sed- imentary rock, in which such minute animals were imbedded, and it would utterly forbid the supposition that it came from a primitive molt- en interior mass. For surely no one will claim that there is any animal life in that central globe of fire. The Moon. 191 CHAPTER XI. THE MOON. Favorably situated for telescopic observation Has the moon an atmosphere ? Or water ? Shape of the moon Is the moon a frozen-up world ? NEAREST of the heavenly bodies ; almost equal in apparent magnitude to the sun ; shining with pure, steady, and serene light; waxing and waning with undeviating regular- ity, the moon is one of the most interesting objects of nocturnal observation. Its mean distance from the earth is at present estimated to be about 238,800 miles. Its diameter is 2,162.3 miles. Its entire surface, therefore, is about 14,500,000 square miles. So near to us, is it strange that it has been the subject of in- terminable conjecture and speculation ? Its nearness excites the more persistent examina- tion, because it inspires the greatest hopes of arriving at certain knowledge. These hopes have been encouraged by another fact. The same hemisphere of the moon is always turned 192 THE MODERN GENESIS. toward the earth. So the telescopic observer is able to fix his attention on any given spot, and he knows that the axial rotation of the moon is not going to slip that spot out of his view immediately. So long as the moon itself is in view the spot he is examining will remain in view. There is, however, one circumstance that diminishes our satisfaction with this situation of things. "There is a large area upon the moon's surface that is absolutely unobservable by us. The total area brought into view, in- cluding that exposed by the moon's librations, does not exceed three fifths of the whole surface. Astronomers have long held that there was but little, if any, atmosphere upon the moon. They thought, however, that they detected the existence of extended seas, and lunar maps were made on which the seas were shown, with names to distinguish them. When we reflect that there was supposed to be no atmosphere, and consequently there could be no wild lunar storms, we are not surprised to find among the seas a Mare Tranquillitatis and a Mare Seren- itatis. The Moon. 193 That the moon has no atmosphere has been inferred from the fact that a planet or star in occultation with the moon seemed to pass out of sight instantly, as it would not do if there were an atmosphere to refract its light. Airy has shown that if there be a lunar atmosphere its refractive power cannot exceed -$^-5 part of that of the atmosphere of the earth. Sir William Herschell gave this subject spe- cial attention. On the 5th of September, 1793, during a solar eclipse, he observed with great care the acute horn resulting from the inter- section of the limbs of the sun and the moon. " His deduction, from his observations, was, that if there had been a deviation of one sec- ond, caused by the refraction of the solar light by a lunar atmosphere, it would not have escaped him." Spectrum analysis has also been directed to the determination of this question. Fraun- hofer, Brewster, Huggins, Gladstone, Miller, Jansen, and others have respectively made it the subject of study. " From the entire ab- sence of any special absorption lines," Schellen says, " it must be concluded that there is no atmosphere in the moon." 13 194 THE MODERN GENESIS. With the conviction that the moon is desti- tute of an atmosphere, there has also come a general conviction that there are no bodies of water on the moon, and those areas, which were formerly supposed to be seas, are now supposed to be sandy plains. Some think that they retain the marks of former sea bottoms ; some see in them the evidences of aerial action, and they fancy that there once existed both air and water on the moon. Some account for the disappearance of the water by supposing that the volcanic agencies produced such im- mense subterraneous caverns that the waters all drained off into them ; but Winchell sup- poses the rocks to have literally absorbed them, together with the atmosphere. We are not writing a lunar history, and therefore it is all one to us whether there be a lunar atmosphere and lunar seas or not. We have no theory that requires the assumption that they did once exist, and which, if they are found not to exist at the present time, must account for their disappearance. But the moon is, in the nebular theory, a representative body. It represents the " Lu- nar Stage," that is, the stage of final refriger- The Moon. 195 ation, and what the moon now is, that the earth, the planets, and the sun are destined to become. Leaving for a moment the question of the physical condition of the moon as an unsettled question, which it is, we remark that the moon performs an important office in its effects on terrestrial economy. Perhaps no one can ap- preciate at its real value the benefit to all ter- restrial life of that tidal movement whose efficient cause is the lunar attraction. But to return, the advocates of the nebular theory point us to evidences of great volcanic activity on the moon during some periods of its history. And no one can deny that there is the appearance on the hither hemisphere of the moon of such activity. Steep precipices ; lofty rocky mountains, unrelieved by vegeta- tion; extensive parks of barren sand, sur- rounded by rugged ridges of naked rocks ; great cavities, not unlike some of the extinct craters of the earth, combine to make upon us the impression that we have before us a scene of absolute desolation. But no volcanoes are found at present in action. Sir William Herschell thought at one 196 THE MODERN GENESIS. time that he had seen an eruption of a lunar volcano, but Arago expresses strong doubts of the reality of the eruption. We think it quite probable that no active volcano exists on the hither side of the moon. Here, now, are three facts at least they are supposed to be facts : there is no atmosphere in the moon, there is no water in the moon, there is no volcanic activity in the moon. From these three facts the nebular theory is supposed to have strong confirmation, and the lunar history is readily written as follows : The moon was detached from the earth while it was an aeriform body. Being a very small body it rapidly cooled off and contracted, and its elements combined ; it became liquid, and a crust was formed upon it ; and there was an atmosphere ; and there were seas ; and subsequently there were great convulsions ; the internal fires generated forces that lifted portions of the crust, or broke through as vol- canoes. All these changes occurred with great rapidity compared with the corresponding changes in the earth, because the moon is so small. At length the lunar fires burned quite out, the volcanic activity ceased. At one Tlie Moon. 197 time there was life on the moon. The lunar seas were full of lunar fishes, the lunar air was cleft by wings of lunar birds, the lunar forests were thronged by lunar beasts. Then, too, some higher type of being, answering to that of man on the earth, reigned over all the lunar realms. But that was in the long, long ago. The historic periods succeeded each other rapidly. The internal fires were spent. The whole mass became solid. The solid structure became gradually chilled. The rocks eagerly drank up the water, and, still unsatisfied, ab- sorbed the atmosphere, and now the heat is quite exhausted. All life has become extinct. The moon is a frozen world, and it hangs in the heavens an impressive example of a single stage of planetary history. As the rings of Saturn were an example and a demonstration of the ring stage of planetary evolution, so the frozen-up moon is an exam- ple and a demonstration of planetary congela- tion ; and it follows that all planetary history begins in fire-mist, passes through successive stages of cooling, contracting, solidifying, con- vulsing, renewing, etc., until the end shall come in a universal waste of frozen, desolate, 198 THE MODERN GENESIS. wandering spheres, wrapped in the darkness of eternal night, the sun itself shrunken and frozen. Such may be the end foreshadowed. And it is not the province of true science to shed tears over the foreseen catastrophe. It is only her province to take the facts of history, as the great plan of nature is unfolded, and interpret them on known natural principles. And yet the generalizations of science should not be too precipitate. Moderation and self-distrust are as likely to be needed here as in any sphere of scientific inquiry. What we know, not what we imagine or what we conjecture, should be the basis of our generalization. Do we know enough about the moon to pronounce pos- itively as to its physical condition ? Do we know that it is frozen up ? Do we know that there is neither air nor water on the moon ? True, we see no signs of air on the hither hem- isphere. No clouds float across its disk. And both the telescope and the spectroscope fail to find any indications of an atmosphere. But let us not forget that there are about six millions of square miles of lunar surface that we have not examined, and cannot examine with the The Moon. 199 telescope or spectroscope. Who can tell what is there out of sight ? Is there any means by which we can arrive at the probabilities in the case ? It may be said that the probabilities are just what the general opinion of scientists is, and the general opinion is that there is no atmosphere and no water on the moon. And there is weight in this fact, for it is to be presumed that scientists will not commit themselves to an opinion which has not a high degree of probability. But it will not be considered disrespectful to re-open the ques- tion. The inaccessibility of the farther lunar hemisphere is itself a factor to be considered in the solution of this problem. Why can we not observe that hemisphere ? Why is it al- ways turned away from us? Evidently be- cause the moon is not balanced upon its own center. The hemisphere of greater density is toward the earth, and the earth holds it there, (not exactly steadily, for it has its librations,) and it cannot change its relations. The hemisphere of lesser density, then, is out of sight. Now let us consider the effect of the moon's motion on the moon's form. We agree that the form of each of the planet- 200 THE MODERN GENESIS. ary bodies is affected by its axial rotation. The effect on the earth has been to give it an oblateness of T J T ; on Mars, to give it an oblate- ness of ^V ! n Jupiter, to give it an oblateness of Jy ; and on Saturn, to give it an oblateness of T V- But is any such effect possible to the moon ? We venture to express the convic- tion that it is not. The moon, then, cannot be an oblate spheroid. Why do we come to this conclusion? Be- cause of the moon's diurnal motion. The moon does not revolve upon its own axis as the earth does and as other planets do. The earth is the center of its diurnal rotation. If an artificial globe be firmly fixed to the end of an arm which moves around a fixed point, it will fairly represent the moon's motion. Is there any centrifugal force generated? Yes. What effect will it have on the moon ? It will cause it to tend to fly off bodily from the cen- ter. Will it affect its form? If it does, it must raise its outer hemisphere, and give to the body an oval or ovate form. The form, we think, must be ovate. If any fluid matter does exist on the moon, this motion of the body must necessarily throw it to or toward The Moon. 201 the other side. We are not certain that this would not be the case if we should consider the moon a solid body in the sense in which the crust of the earth is a solid body. For in this solid crust are cavities, and seams, and chan- nels, in which water may be, and through which it may pass. Suppose, then, that the whole earth be thus solid, and that its axial rotation be arrested, and it go on in its orbit as usual. Would not all the oceans be piled up on one side, and that the side opposite to the sun? And all the water that was land-locked, so that it could not pass over, would gradually strain through to, or toward, that other side. Take a sponge and attach it to a revolving arm will not the moisture all collect at that side which is most distant from the center of rotation, provided the rotation be sufficiently rapid ? Just so, if there be any atmosphere and any water on the moon, the effect of this known motion of the moon must be to gather all the surface-water and most of the air to that farther side which is inaccessible to our observation. We say most of the air, because we conceive that the expansibility of air would 202 THE MODERN GENESIS. probably cause it to extend over the whole surface, but not of equal depths. This supposition as to the waters of the moon does not exclude the possibility of vol- canic action on the hither lunar hemisphere. If volcanoes originate in the chemical changes which may take place in the rocks, such changes may be supposed to have been in progress for ages, and the absence of such agencies as are so powerful on the earth in modifying the surface appearance (the aque- ous and aerial agencies) would have the effect to leave the volcanic chasms, and ridges, and rents just as the volcanic action itself shaped them, and we, who look down into the awful depths of those craters, behold them just as they were left by the receding fires. On the earth heat, cold, moisture, and the force of the wind, destroy the original ruggedness of terrestrial mountains. In the absence of water and air the alternations of .temperature and cold would affect them but slightly. It may be said that these thoughts touch- ing a possible condition of the moon are but speculative. True ; and so, too, the T}u Moon. 203 theory which represents the moon as "a fossil world, an ancient cinder," is but a spec- ulative theory. We do not know that one hemisphere of the moon has water on its surface, but we know that with the moon's known diurnal motion, if there be any water on the moon, it would find that side and would stay there. And inasmuch as that is the case, the blistered, waterless, and airless aspects of the hither hemisphere are no ground at all for the conclusion that the oceans and atmosphere of the moon are sucked up by the rocks, and have totally disappeared from the lunar surface. It certainly is not demonstrable that the moon is a frozen-up world, having. a temperature like that which prevails at the top of the Himalayas and the Alps. Nor is it demonstrable that it is a hab- itable world. Our consideration of its aspects and its motions leads us to the conclusion that it may be habitable, but if so it is only in one hemisphere, and that the hemisphere we are unable to observe. According to very recent thermometrical experiments the moon actually does emit heat in quantities sufficient to pro- duce sensible effects at the distance of the 204 THE MODERN GENESIS. earth. Fourteen and a half days of unclouded sunshine on the hither hemisphere of the moon, it is now estimated, produces in it an average temperature of boiling water. Cer- tainly it is not a reliable subject from which to deduce that portion of the cosmical history which is called " the lunar stage," or stage of final refrigeration. Fourteen and a half days of continual sunshine would also cause the waters of the farther hemisphere to evaporate rapidly, and we can imagine dense clouds forming and protecting that hemisphere from the heat of the long-continued day, and mit- igating the rigors of an equally protracted night. Since penning the foregoing we have, by a happy chance, opened the " Annual of Scien- tific Discovery," for 1858, to the following interesting account of the occultation of Ju- piter by the moon, which occurred on the 2d of January, 1857. We quote a portion only of the article : " But the most interesting fact yet remains to be told. The bright border of the moon at this time crossed the soft green face of the planet, not with a clear, sharply-cu-t outline, The Moon. 205 like that which had been presented as the disc, passed into concealment ; it was fringed by a streak or band of graduated shadow, commenc- ing at the moon's edge as a deep-black line, and being then stippled off outwardly until it dissolved away in the green light of the plan- et's face. This shade-band was about a tenth part of the planet's disc broad, and of equal breadth from end to end. Mr. Lassell de- scribed it as offering to his practiced eye pre- cisely the same appearance the obscure ring of Saturn presents to a higher magnifying power where that appendage crosses in front of the body of the Saturnian sphere. There could be no mistake concerning the actual existence of this curious and unexpected apparition. It was independently noticed and described by at least six trustworthy observers, and the descriptions of it, given by each of these, cor- responded with the minutest accuracy. The shadow was seen and described by Mr. Lassell, at Liverpool; by the Rev. Professor Challis, at the Observatory at Cambridge; by the Rev. W. R. Dawes, at Wateringbury ; by Dr. Mann and Captain Swingburne, at Ventnor ; and by Mr. William Simms, at Carshalton. It there- 206 THE MODERN GENESIS. fore only needs that the unusual presence should be accounted for; the handwriting being there, the question remains to be an- swered, ' Can its interpretation be found ? ' Can science read the meaning of this shadow- fringe inscription ? Are there minds that can fathom, as well as eyes that could catch, this signal hint thrown out by Jupiter at the in- stant of its emergence from its forced conceal- ment behind the moon ? " It was Mr. Dawes's impression, on the in- stant, that the mysterious shadow was simply an optical spectrum, a deep, blue fringe to the light haze caused by the object-glass of his tel- escope having been accidentally over-corrected for one of the irregularities incident to chro- matic refraction. This notion, of course, became altogether untenable so soon as it was known that the same appearance had been noted by other telescopes in which the same incidental imperfection had had no place. All felt that the shadow could not be referred to a regular atmospheric investment of the moon's solid sphere, because, under such circumstances, the streak should have always been seen when the rim of the moon The Moon. 207 rested in a similar way across a planetary disc. " The sagacious Plumian, professor of astron- omy at Cambridge, Professor Challis, seems to have been the first to hit upon the true inter- pretation of the riddle. The indefatigable star-seer has long suspected that the broad, dark patches of the lunar surface the seas of the old selenographists are really shallow ba- sins, filled with a sediment of vapor which has settled down into those depressions; in other words, he conceived that there are fog seas, although there are no water seas, in the moon. The general surface and higher projections of the lunar spheroid are altogether uncovered and bare ; but vapors and mists have rolled down into the lower regions in sufficient quan- tities to fill up the basin-like hollows exactly as water has gravitated into the beds of the terrestrial oceans. The professor, using the high powers of the magnificent telescope fur- nished to the Cambridge Observatory by the munificence of the late Duke of Northumber- land, was able to satisfy himself that the planet actually did come out from behind a widely- gaping hollow of the moon's surface at the 2o8 THE MODERN GENESIS. bottom of a lunar fog sea, seen edgewise, so to speak. If a shallow basin extended for some distance round the curvature of the lunar spheroid, and if it were filled up with vapor, that vapor would rest at a fixed level, exactly after the manner of a collection of liquid, and such fixed level would be concentric with the general spheroidal curvature of the satellite. Under such an arrangement there would, there- fore, necessarily be a bulging protuberance of the vapor-surface through which a remote lu- minary might be seen when it rested in the requisite position. This, then, is Professor Challis's understanding of Jupiter's hint. The moon has fog seas upon her surface, and the band of shadow visible upon the face of Jupiter, as the planet came out from behind the earth's satellite, was a thin upper slice of one of those fog seas seen by the favorable accident of the planet's light shining for the instant from beyond." We reproduce this for this purpose only, to show by it how little ground there is to pro- nounce dogmatically, as Professor Winchell does, that "the moon is a fossil world, an ancient cinder," etc., exemplifying an extreme The Moon. 209 state of refrigeration to which all planeta- ry bodies and the sun itself are finally to come. So far as our knowledge of that satellite goes, it authorizes no such conclusion. 14 2io THE MODERN GENESIS. CHAPTER XII. THE SUN. Its volume Density Temperature Relation to the plan- ets Nebular theory applied to the sun Material constit- uents Origin of the Sun's heat Theory of Helmholtz Theory of Mayer Views of Winchell. THE sun is in all respects the most impor- tant body in the solar system. We have given it some general consideration, but it de- mands more particular and extended examin- ation. We now propose to group together the principal facts that are known respecting this great luminary, and then proceed to an exam- ination of the theoretical inferences drawn from these facts. The magnitude of the sun is amazing. Tak- ing the volume of the earth as unity, that of the sun is about one million two hundred and fifty thousand. Conceive of the sun as a hol- low sphere, with the earth in its center, then the moon might revolve around the earth at its present distance, midway between the earth The Sun. 211 and the solar shell. Were all the planets united in one body, without any change of density, the sun would equal five hundred such bodies. But if all the planetary bodies could be reduced to a common density, the density of the sun itself, and united in one body, then the sun would equal seven hundred such bodies. Vast as the magnitude of the sun is, how- ever, it would require three hundred and forty billions of such magnitudes to equal that of the original cosmical mass of the nebular theory at the period when Neptune was separated from the parent mass ; and we shall be pre- pared by this fact to contemplate the sun's present magnitude without extravagant emo- tions. The sun is a self-luminous body, and is the source of light and heat to the entire planetary system. The physical constitution of the sun has been the subject of infinite speculation. That it is a material body, hav- ing a specific gravity about one fourth that of the earth, that its gravitative force acts on all planetary matter, and that it binds the planets and satellites and asteroids together in one great system, are facts which have long been 212 THE MODERN GENESIS. established. And it was only natural to con- jecture that the material elements of the sun and the material elements of the planets were as kindred in character as were the forces that were known to be active between them. Men who have reflected were not, therefore, startled into inordinate raptures when that wonderful little instrument, the spectroscope, announced positively and authoritatively that the sun surely contains many of the very same elements contained by the earth. This is only what men have believed to be true for ages. There may be elements in the earth yet un- known to science ; and there may be elements in the sun that are not present in the earth ; and there may be elements in the stars that are not in either the sun or the earth, nor yet in any of the planets. Certain it is that there are spectra which the most eminent and skill- ful spectroscopists are unable to refer to any known element. But the majority of the elements may be common to all suns and planets, the quantities of each being distributed with reference to the office which each body has to perform in the great system of nature. The physical consti- The Sun. 213 tution and condition of the sun, therefore, may be presumed to be exactly what its rela- tion to all the planetary bodies requires. Be- tween the sun and those bodies are vast spaces, yet not so vast as at all to embarrass the force by which they are bound together, or to hin- der the efficiency of that solar influence which enlightens and warms them. Such reflections, though concurred in by the physicist and astronomer, do not satisfy them. They would like to know the exact structure of the sun, the condition of its matter, the nature of the solar spots, the origin of its light. Why is the sun self-luminous ? How does it generate its heat ? A thousand questions have been raised, and men have been ready with answers. And yet the questions are as far from being wholly satisfied as ever. So long ago as 1769 Dr. Wilson, of Glas- gow, suggested that the sun might be an opaque body, surrounded by a luminous at- mosphere. Sir William Herschell, in 1795, declared himself convinced that the light-giv- ing substance of the sun was neither liquid nor elastic fluid, but something analogous to our clouds, and that it floated in the trans- 214 THE MODERN GENESIS. parent atmosphere of that luminary. He con- ceived that there were two atmospheres, en- dowed with separate and independent motions. The solar spots were openings in the luminous atmosphere, through which the dark body of the sun could be seen. Sir David Brewster thought that the non^luminous rays that are found in solar light might have been emitted by the dark body of the sun, and the luminous rays have been emitted by the luminous mat- ter. " With this hypothesis," says Sir David, " we could readily explain why it is hottest when there are most spots, because the heat of the nucleus would then reach us without having been weakened by the atmosphere that it usually has to traverse." But so far as we know, it is not " hottest when there are most spots." Other astronomers have suggested the ex- istence of a third atmosphere, non-luminous and transparent, as indicated by the diminished brightness of the sun's disk toward the edges. In our times the solar light serves the cause of science in ways of which the ancients did not so much as dream. Photography assists the celestial explorer by catching the image The Sun. 215 of the celestial body, and fixing it for his delib- erate examination. Thus the solar spots and protuberances have been subjected to a scru- tiny which was impossible to simple telescopic observation. The spectroscope, also, has greatly enlarged the boundaries of our knowledge of solar af- fairs, although it must be confessed that dis- tinguished spectroscopists are not fully agreed respecting the constitution of the sun. Kirch- hoff 's theory is, however, generally accepted. We take the liberty to quote the following from Schellen : " According to Kirchhoff the sun consists of a solid or partially liquid nucleus in the high- est state of incandescence, which emits, like all incandescent bodies, every possible kind of light, and, therefore, would of itself give a con- tinuous spectrum without any dark lines. This incandescent central nucleus is surrounded by an atmosphere of lower temperature, contain- ing, on account of the extreme heat of the nu- cleus, the vapors of many of the substances of which this body is composed. The rays of light, therefore, emitted by the nucleus, must pass through this atmosphere before reaching 216 THE MODERN GENESIS. the earth, and each vapor extinguishes from the white light those rays which it would itself emit in a glowing state. Now it is found, when the sun's light is analyzed by a prism, that a multitude of rays are extinguished, and just those rays which would be emitted by the vapors of sodium, iron, calcium, magnesium, etc., were they made self-luminous ; conse- quently the vapors of the following substances, sodium, iron, potassium, calcium, barium, mag- nesium, manganese, titanium, chromium, nick- el, cobalt, hydrogen, and, probably, also zinc, copper, and gold, must exist in the solar at- mosphere, and these metals must also be present to a considerable extent in the body of the sun." Kirchhoff explains the solar spots on the supposition that they are cloud-like masses of condensed vapor floating in the solar atmos- phere, and intercepting the rays of light that proceed from the incandescent nucleus. Faye, on the other hand, supposes the act- ual nucleus of the sun to be a non-luminous globe of gas, and the solar spots to be huge rents or openings through the luminous envel- ope, which is called the photosphere. Here are three theories of the solar constitu- The Sun. 217 tion. Could we believe with Wilson and Her- schell, we might imagine the sun a very de- lightful residence ; its dark central body vari- egated by mountains and valleys, oceans, seas, lakes, and rivers, continents and islands, in in- finite variety ; with an equable and constant climate, no tropical heats and polar frosts, but a uniformly pleasant and fruitful season, con- tinuing forever ; no night, but one unchang- ing day, while its luminous atmosphere, thou- sands of miles away, filters its light and heat down through the lower atmosphere upon the whole solar body alike. But Kirchhoff dispels the happy illusion, and turns our continents into white-hot liquids or solids, while Faye turns the solids and liquids into gas. We will be excused from a residence in the sun, if you please. Later experiments than those upon which Kirchhoff based his theory, have shown that conditions of temperature and pressure may exist under which gases will give unbroken spectra, just as incandescent solids and liquids do ; and so it may be that the light transmit- ted from the sun is not from a solid or liquid incandescent body. 218 THE MODERN GENESIS. That distinguished Italian spectroscopist, Sechi, thinks that there exists aqueous vapor in the vicinity of the large spots. In 1868 the French astronomer, Janssen, while watching the total eclipse of the sun from a station in India, noticed that the solar prominences gave a spectrum of three bright lines, indicating that the prominences were vast columns of incandescent hydrogen. Lockyer, in England, had already noticed the same phenomenon without the eclipse. He gives the following views, deduced from his observations : " Now these again are facts which bear upon the sun's condition in a very great degree ; indeed, they lead us necessarily to several important modifications of the received theory of the physical constitution of our cen- tral luminary ; the theory which we owe to Kirchhoff, who based it upon his examination of the solar spectrum. According to his idea the photosphere itself is either solid or liquid, and is surrounded by an extensive non- luminous atmosphere, composed of gases and the vapors of the substances incandescent in the photosphere. " Kirchhoff's idea demands dense vapors The Sun, 219 far above where we have found hydrogen alone, and that very rare. So that we must consider that the absorption, to which the reversal of the spectrum and the Fraunhofer lines are due, takes place in the photosphere itself, or extremely near to it, instead of in an exten- sive outer absorbing atmosphere ; so that we may say that the photosphere, plus the chro- mosphere, is the real atmosphere of the sun, and that the sun itself is in such a state of fervid heat that the outer border of its atmos- phere, that is, the chromosphere, is in a state of incandescence." Professor Young, probably the most distin- guished spectroscopist of America, has sub- mitted another theory. He supposes the existence of a liquid solar crust, which re- strains the gases for a time, after which they break through in jets. M. Soret finds, with Lockyer, that the higher atmosphere of the sun consists of nothing but hydrogen. This certainly is a very peculiar condition. Another circumstance seems to us most strange, if we can trust the announcements of the spectro- scope. " The spectra of the metals, silver, mercury, antimony, arsenic, tin, lead, cad- 22o THE MODERN GENESIS. mium, strontium, and lithium, show no coin- cidence with the Fraunhofer lines, and this is also the case with the two non-metallic sub- stances, silicen and oxygen." Schellen. Is there, then, no silver, no mercury, no oxygen in the sun ? So much fire and no oxygen ! No combustion ! No other single element plays so important a part in the terrestrial economy as oxygen. No other has so wide a range of affinity. All the elements combine with it, unless fluorine be an exception. Nothing can equal the inten- sity of its attractions. It is one fifth of the atmosphere. It is three fourths of all animal bodies. It constitutes four fifths of every veg- etable structure. Eight ninths of the weight of all the water is oxygen, and it is, so far as man has been able to determine, one half of the weight of the entire globe. Now how is it that an element so abundant in the earth, and of such importance, is not found in the sun, if the sun is but the residual portion of that cosmical mass out of which the earth was taken ? If one should say, because oxygen is a gas and being light, it was more easily cast off, we should reply, Why, then, do The Stin. 221 we still find a stratum of hydrogen of five to seven thousand miles in depth in the sun ? Is not hydrogen lighter than oxygen ? But whatever may be the physical constitu- tion of the sun, it is universally agreed that it is the chief source of light and heat, not only to the earth, but to all other planetary bodies. Moreover, it is agreed that but a small part of the light and heat radiated from the sun ever reaches the planets. Much the larger portion is dissipated in space. Conceive of a spherical shell, one hundred and eighty-three millions of miles in diameter, with the sun at its center. Now conceive of a circular spot on the surface of this shell, whose area is equal to that of a great circle of the earth. What is the ratio of the area of this spot to that of the sphere itself? Such will be the ratio of the light and heat received from the sun by the earth, to the total radiation from the sun. From this it will be seen that the total radiation is more than two billion times as much as is received by the earth. It becomes, therefore, a question of universal interest, What, is the temperature of the sun ? If astronomers and physicists have been un- 222 THE MODERN GENESIS. able to agree as to the physical constitution of the sun, no more are they agreed as to its temperature. There has been no lack of experiments on the sun's heat. Instruments and methods of measurement of the most diverse character have been employed. Estimates have been based on these experiments, and the result is, the estimates are irreconcilably discordant. Sir John Herschell estimated that a solid shaft of ice, forty-five miles in diameter, plunged endwise into the sun at the rate of one hundred and ninety thousand miles per second, would be melted as fast as it entered. Sechi estimates the sun's temperature at two million degrees centigrade. Ericsson places it at six million to seven million degrees. But distinguished French physicists of the present day contend that it cannot exceed ten thou- sand degrees, and think it more likely that it does not exceed three thousand degrees. Here is a wide range of opinions touching the temperature of the sun from three thousand degrees to ten million degrees. The utmost that is known of this matter is that the sun is the source of heat as The Sun. 223 well as of light, and that the heat is immeas- urable. There is one other solar problem, and in some respects it is the most important of all. We know that the sun has furnished a suffi- cient supply of heat for long periods in the past, and that it furnishes a sufficient supply at present ; but the question of future supply is one of so much interest that eminent phys- icists have devoted considerable labor to the settlement of it. But in its settlement they have proceeded from different premises. The first question which arises is, What keeps up the solar temperature itself? Helmholtz assumes that the whole of the heat of the sun arises from the condensation of its mass. He says : " It may be calculated that if the diameter of the sun were diminished only the ten thousandth part of its present length, by this act a sufficient quantity of heat would be generated to cover the total omission for two thousand one hundred years." Dr. Sterry Hunt embraces substantially the same views. He says : " The sun, then, is to be conceived of as an immense mass of intensely 224 THE MODERN GENESIS. heated gaseous and dissociated matter, so con- densed, however, that, notwithstanding its excessive temperature, it has a specific grav- ity not much below that of water, [but the density of the sun is one and a half that of water,] probably offering a condition analogous to that which Cagniard De La Tour observed for volatile bodies when submitted to great pressure at temperatures much above their boiling point. The radiation of heat going on from the surface of such an intensely heated mass of uncombined gases will produce a su- perficial cooling, which will permit the combi- nation of certain elements and the production of solid or liquid particles ; these, suspended in the still dissociated vapors, become in- tensely luminous, and form the solar photo- sphere. The condensed particles carried down into the intensely heated mass, again meet with a heat of dissociation, so that the process of combination at the surface is -incessantly re- newed, while the heat of the sun may be sup- posed to be maintained by the slow condensation of its mass." But Professor Winchell distinctly repudiates the condensation theory, as follows : " Condcn- The Sun. 225 sation through loss of heat would create no tend- ency to increase the temperature, but condensa- tion through the action of gravity would. The latter cause of condensation could only exist in a mass of matter temporarily out of the condition of molecular equilibrium, and could continue only while it is in the act of adapting its molec- ular state to the mechanical forces acting upon it. " We are unable to state whether these forces vary in different regions and periods, and hence cannot safely assert that every, or any, nebulous body increases in temperature during any period of its history. // seems more probable that a continuous reduction of temperature is experienced, and that the temper- ature inherent in the sun at the present time is rather the residuum of the primordial heat than the effect of the condensation of his mass." Professors Young, Tyndall, and others, ad- vocate the meteoric theory of Mayer, and also the condensation theory of Helmholtz. Pro- fessor Young says : " The proper view is that the heat is maintained by the influx of mat- ter. As meteors fall upon the earth, several 15 226 THE MODERN GENESIS. millions in a day, so they fall into the sun, millions of millions per day, and contribute to the solar heat. But that does not account for it all. Another cause, I doubt not, is the con- traction of its volume. If the sun were to con- tract one hundred and twenty feet in radius, or two hundred and forty feet in diameter, in a year, that would account for all the heat it gives off." The meteoric theory of Mayer deserves a fuller exhibit. Perhaps no clearer statement of it has been made than that by Professor Thompson, who says : " In conclusion, then, the source of energy from which solar heat is derived is undoubtedly meteoric. The prin- cipal source, perhaps the sole appreciable effi- cient source, is in bodies circulating round the sun, at present inside the earth's orbit, in the sunlight by us called the zodiacal light. The store of energy for future sunlight is at pres- ent partly dynamical that of the motions of these bodies round the sun and partly poten- tial that of gravity toward the sun. This latter is being gradually spent, half against the resisting medium, and half in causing a contin- ual increase of the former. Each meteor thus TJie Sun. 227 goes on moving faster and faster, and getting nearer and nearer the center, until some time, very suddenly, it gets so much entangled in the solar atmosphere as to begin to lose veloc- ity. In a few seconds more it is at rest on the sun's surface, and the energy given up is vi- brated across the district where it was gath- ered during so many ages, ultimately to pen- etrate as light the remotest regions of space. Professor Tyndall, whether indorsing this meteoric theory directly or not, seems to give it countenance, and, following Helmholtz, gen- eralizes in a most fascinating manner the history of the winding up of planetary affairs, as follows : " Solar light and heat lie latent in the force which pulls an apple to the ground. The po- tential energy of gravitation was the original form of all the energy in the universe. As surely as the weights of a clock run down to their lowest position, from which they can never rise again unless fresh energy is commu- nicated to them from some source not yet ex- hausted, so surely must planet after planet creep in, age by age, toward the sun. When 228 THE MODERN GENESIS. each comes within a few hundred thousand miles of his surface, if he is still incandescent, it will be melted and driven into vapor by ra- diant heat.* Nor if he be crusted over and become dark and cool externally, can the doomed planet escape its fiery end. If it does not become incandescent like a shooting star, by friction in its passage through his atmos- phere, its first graze on his surface must pro- duce a stupendous flash of light and heat. It may be at once, or it may be after two or three bounds, like a cannon shot ricochetting on a surface of earth or water, the whole mass must be crushed, melted, and evaporated by *a crash, generating in a moment some thousand times as much heat as a coal of the same size would produce by burning." Here is utterance sufficiently positive. If Tyndall were not a scientist, one might mis- take him for a theologian of the old dogmatic type. One can scarcely resist the impression * Prof. Tyndall ought to explain how the sun, which is not hot enough to be converted into vapor itself, can possibly convert a planet into vapor, while the said planet is yet " A few hundred thousand miles" away from "his surface." Is the radiant heat of the sun greater than the resident heat of the same body ? The Sun. 229 that the school of popular scientists are in danger of becoming dogmatical, especially on those questions that transcend their analysis. It must be evident that the source of the sun's heat remains as uncertain as ever. Even the spectroscope, from which more has been expected than from all other instruments, gives us some equivocal answers, so that at one time we find that the sun has a solid or liquid nucleus, and at other times we are as- sured that it is gaseous. But neither spectro- scope, telescope, or any other device, is able to inform us how the solar energy is maintained. .Helmholtz, in the elation of an original thought, leaped to the conclusion that the condensation of the solar mass must maintain its temper- ature. Tyndall, with equal enthusiasm, fol- lows. Both see the planetary mechanism run- ning down. But Helmholtz is far less assured and dogmatic than his followers. Thompson pronounces dogmatically on the zodiacal light, as if he knew what the zo- diacal light is. It consists of meteors, he as- sumes, yet no astronomer has ever yet seen one of these meteors. No perturbations of Venus or Mercury or our moon has ever in- 230 THE MODERN GENESIS. formed us of the existence of such a belt of meteors as is assumed. No one has ever seen any meteoric body, great or small, fall to the sun ; and there are not wanting scientists of sufficient hardihood to explain the zodiacal light on principles which locate it in the earth's atmosphere, just as the rainbow is located on the cloud, both being effects of the reflection and refraction of the sunlight. But what if the zodiacal light be the reflec- tion of the sun's light from a nebulous ring, as Laplace supposed, does it follow that the sun is constantly devouring that ring, and thus maintaining its own heat? To us these spec- ulations seem idle. Whence such a ring ? Does the cosmical parent turn around and be- gin to devour his offspring as soon as it is born? But let us return. It is strange that the advocates of the nebular hypothesis, who are so busy seeking out some way of accounting for the continued heat of the sun, do not see that the original temperature of the elements must have been the highest temperature to which they have ever been raised if the theory be allowed. The Sun. 231 How do we know that? We answer: We know it, because the theory supposes all the matter of the solar system to have been in a state of gas gas so attenuated that three cu- bic miles of it would have weighed only a sin- gle grain. Now what force can vaporize the elements but heat? And what heat is that which can convert them all into vapor ? Now such a heat as would not only vaporize all the metals and metallic earths, but also attenuate their vapors to such an extent, is truly incon- ceivable. No such temperature exists in the solar system, or anywhere else, so far as we know, at the present time. Certainly no such heat exists in the sun, for the density of that body is 1.5. How many degrees of heat are necessary to convert the mass of this density into such a vapor as the original cosmical mass is supposed to have been ? No one can fail to see that Winchell is the only consistent theorist among all that we have collated. A " primordial heat," adequate to the ex- pansion of the matter of the solar system to the volume required by the Nebular Hypoth- esis, would never need to be increased. We come to the conclusion, then, that if the neb- 232 THE MODERN GENESIS. ular theory be accepted, all these theories of heat generation, whereby the solar temper- ature may be maintained, must be laid aside as irreconcilable with that theory. True, the theories themselves are undemon- strated and undemonstrable. The only cer- tain thing about them, when examined inde- pendently, is their uncertainty. But when examined upon the previously accepted Neb- ular Hypothesis, they cease to possess the least credibility. Let us, therefore, dismiss them, and consider the sun as cooling off. If the sun is cooling off and condensing, it must be obedient to the same law, in this respect, as any other of the bodies which were once a por- tion of its mass. Let us, then, compare the sun with the earth, and see if we find them obedient to the same law, or if they now compare in the mat- ter of density as they must compare if the theory be true. At the time that the earth-mass is supposed by the theory to have been detached, the cos- mical mass was a body having a diameter of one hundred and eighty-three millions of miles. Now, after detaching the earth, Venus, and The Sun. 233 Mercury, it has shrunken to the diameter of eight hundred and fifty thousand miles. Dur- ing that period its density must have become making no allowance for the abstraction of Venus and Mercury almost ten million times as great as it was at its beginning, because its volume then was about ten million times as great as its volume now is. But the earth has condensed three hundred and fifteen thousand times as fast as the sun, because the mass of the sun is three hundred and fifteen thousand times as great as that of the earth. The earth, then, must now be many thousand times as dense as the sun. But it is not. It is only about four times as dense as the sun. It cannot be said that this is because the lighter matter was thrown off in the earth- mass, for we know that some of the heavier elements which are present in the earth are not detected in the sun, and that the lightest of all substances, hydrogen, is abundant in the sun. The relative densities of the sun and the earth are irreconcilable so it seems to us with the nebular theory. It is conceded that there is an outer atmos- phere of pure hydrogen enveloping the sun. 234 THE MODERN GENESIS. It is also universally agreed that there is a vi- olent agitation of the chromosphere. Vast tongues of flame, many thousand miles high, have been observed. How is it possible, on the principle of the nebular theory, that such vast quantities (the hydrogen is five thousand to seven thousand miles in depth) have been retained in the sun, while many very heavy substances, such as platinum, silver, mercury, lead, tin, etc., were thrown off in the terres- trial mass? Tried by one postulate of the nebular theory, the sun is too light ; tried by another postulate of the same theory, the sun is too heavy. Will the apostles of the theory come to the rescue of the sun ? Temperature of the Planets. 235 CHAPTER XIII. TEMPERATURE OF THE PLANETS. I" T must be borne in mind that the nebular * theory is set forth as a history of planetary existence. It not only undertakes to account for the origin of the planetary masses, but it undertakes to explain the successive stages of planetary being. Leaving the original cos- mical mass as a peripheral ring, each planetary mass is supposed to have cooled, contracted, granulated, and united in one body, which, as- suming the spherical form, not only revolved around its original in an orbit, but also re- volved on its own axis. And as, in the original mass, contraction by cooling produced an ac- celeration of the axial rotation, so in the plan- etary mass contraction, by cooling, produced an acceleration of the axial rotation until the planetary mass was enabled to detach periph- eral rings, which became moons, and that all these bodies have gone on cooling and shrink- 236 THE MODERN GENESIS. ing until now. Now it becomes, at least, a curious question, What is the present temper- ature of any one of these planets? But in its relation to the credibility of the neb- ular theory this question becomes one of very grave importance, for, according to that theory, five of these bodies are examples of successive stages of planetary history, and give names to those stages. If, then, it shall appear that the temperature of each of these bodies is what the theory assumes it to be, it furnishes very strong confirmation of the theory as a whole. But, on the other hand, if it shall appear that these bodies do not exhibit the traces of such temperatures as are assigned to them respect- ively by the theory, then they give no testi- mony in favor of the theory. Let the reader keep in mind the order of the history. The Saturnian stage is exemplified by the ring condition of Saturn ; the Jovian stage, by the belted Jupiter; the terrestrial stage, by the habitable earth; the Martial stage, by the post-habitable Mars ; and the lunar stage, by the frozen, shriveled, airless, and waterless moon. Such as these latter planets are supposed to be, such shall all other Temperature of the Planets. 237 planets become, and such shall even the sun himself become at last. This is history. Moreover, it is the custom of a class of scientists to speak of these things as among the established truths of modern science. Saturn, Jupiter, Mars, and the moon are represented as possessing certain physical peculiarities ; these peculiarities are interpreted as the evidences of different temperatures, and the different temperatures mark the different stages of world history. If any one shall dis- credit this theory ; if he shall question these assumed facts ; if he shall speak of the possi- bility of different temperatures in different planets without the supposition of different successive stages of planetary history; if he shall set aside the hypothesis of original high heat and gaseous condition of all matter, he must expect to be denied the honor of scien- tific recognition himself. According to the theory, the older the planet the cooler, provided that volume be equal to volume at the time of the formation of each. If at the time of detachment the planetary masses be of unequal volume, then the larger planet will continue at a high tern- 238 THE MODERN GENESIS. perature longer than the smaller. There is another factor to be considered. Different substances conduct heat away, or, in other words, cool off, with different degrees of rapid- ity. The conducting power of silver is one hundred, while that of iron is but twelve. Dry air is one of the poorest conductors. But we know that the effect of heat on air or gas is such as to throw it into violent agitation. The heated portions are sent to the surface, where its expanded substance is brought into contact with the intense cold, and thus the fee- ble conduction is compensated by the process of convection. Therefore we should conclude that a spherical mass of gaseous or aeriform matter, if it were launched into space at a high temperature, would very rapidly cool off by the process of convection. And if the el- ements composing the aeriform body were such as by condensation become solid, we should expect the period of solidity to approach rap- idly. If this class of elements were present in small proportion, then we should find a small nucleus and an extended aeriform envelope, which would be permanent. It is evident, then, that a planet might be of Temperature of the Planets. 239 very low specific gravity that, for instance, of water and yet not be very warm. More- over, it is conceivable that a planetary nucleus may be large and solid, and yet be of low spe- cific gravity. The nebular theory assumes that the plan- etary masses commenced their independent career in the gaseous state, and it would re- quire a great diminution of the temperature to bring the elements within the reach of the chemical forces. That a heat of dissociation exists in any of the planets is not claimed. But several of the metals do not need to be raised beyond liquefaction to dissociate them and regenerate each by itself pure. We may, therefore, conclude, that whatever elements are in the mass of any one of the planets, all the metals have now reached the stage of liquefac- tion or solidity, and whatever there remains of aeriform matter must be of the nature of an atmosphere surrounding this denser nucleus. But if the constitution of the more distant planets be similar to that of the earth, then can we account for their lightness without sup- posing them to be very hot ? We answer, first, that u'e cannot account for 240 THE MODERN GENESIS. their lightness by supposing them to be very hot. A heat sufficient to give such matter as consti- tutes the earth the specific gravity .of Saturn, supposing that matter to be elementally dis- tributed as it is in the earth, would make that matter incandescent. If, then, Saturn contain all the elements that are in the earth, and in the same proportions, the lightness of Saturn is inexplicable. Supposing it to be very hot would not explain it, unless we suppose it hot enough to render its nucleus incandescent. But that would be to render it a sun. It is a familiar fact that iron can be liquefied, and yet its specific gravity will be scarcely sensibly changed. When run into molds and cooled it does not shrink away from them so as to injure the cast which is formed. The same thing is observable of several other metals. It is also true of the metallic earths, that they may be raised to white heat, and yet their specific gravity is not greatly affected. If they shrank much in cooling the fabrication of symmetrical stone ware and porcelain would be impossible. How great must be that heat which, to any considerable degree, could lower the specific gravity of a planet ! We repeat, it would be Temperature of the Planets. 241 such that the planet would be a sun, shining with its own light. We answer, secondly, We can account for the lightness of Saturn by supposing Saturn to be composed of light matter. As the elements are found unequally distributed on the earth, so it is not irrational to suppose that they may be unequally distributed among the planets. Winchell supposes it to be inevitable that in the formation of the planets by the process of detaching peripheral rings, the lighter matter would be in the outer planets. We confess to a degree of surprise when we find him explain- ing the lightness of Saturn on the supposition that it is very hot. Is it not better, even on the basis of the nebular theory, to suppose Saturn to be composed of very light matter? There are not wanting, even in the earth, materials of sufficient lightness to build a com- paratively light globe out of, if the architect choose to build it out of such material. Cal- cium is a light metal ; so is aluminum. These two metals are the bases of most extensive formations on the earth. Magnesium,- lith- ium, sodium, potassium, chlorine, are all light substances. Carbon, in its most dense form 1G 242 THE MODERN GENESIS. known to us, the diamond, is only three and a half times as heavy as water, and in other forms it is much lighter. Of the heavier met- als, a less proportion may be supposed to be present, without in any way diminishing the stability of the structure. - A solid globe, com- posed of light matter, may be surrounded with an atmosphere of much greater depth than one of the same magnitude composed of denser elements, yet the density of the atmosphere would not be excessive in its lower strata, be- cause the density of the lower air is deter- mined by the weight of the column, and the weight of the column is simply the measure of the total attraction of the mass upon it. If, then, the mass be specifically light, the attrac- tion of a given volume will be proportionately light, and we may suppose that Saturn has a very deep atmosphere, and yet the supposition would not be incompatible with the supposi- tion that Saturn is a habitable world. So much as to the possibilities in this case, with- out reference to the nebular theory. Now let us look again at Saturn in the light of that theory. Saturn is quoted so also is Jupiter to show that the larger bodies cool Temperature of the Planets. 243 off more slowly than the smaller bodies, and thus they exemplify different stages of history. Neptune is a large body, and, though it has been millions of ages cooling and condensing, it has only reached a point where its specific gravity is nine tenths. And Uranus is a large body, though not quite as large as Neptune, nor is it as old. It has not been so long cool- ing off. Yet its specific gravity is one. So much younger, and yet heavier ! How is this ? Why, don't you see ? There are two reasons. First, the first planet was composed of the lightest matter ; and, secondly, the first planet was the larger planet. Being the lighter mat- ter, it never can become as heavy as the sec- ond will become ; and, being the larger body, it cannot cool off so fast, and therefore the second body will condense the more rapidly. The fact is in exact accordance with the theory. But what shall we say about Saturn ? Its original density must have been much greater than that of Neptune, because the volume of the cosmical mass which threw off Neptune was thirty-eight and a half times as great as the volume of the same cosmical mass when it 244 THE MODERN GENESIS. threw off the Saturnian mass. And yet Sa- turn is very light. Its specific gravity is only three fourths. But, it may be answered, Saturn is a very large body, and must cool off and condense more slowly on that account ; and, besides that, Saturn is a much younger body than Uranus, and therefore has not had time to cool off so much, even if it were no larger. Very well, what kind of a body do you really think that Saturn is? An aeriform body? How ? By the force of heat ? Shall we allow that there are substances in Saturn which can become solid ? Then they are solid now, or they are not. If they are solid, then they are in a condition in which the slowness of the process of cooling does not explain the light- ness of Saturn, for we have shown that heat does not so expand the solids as to diminish their specific gravity to any considerable ex- tent. But if they are aeriform by the action of heat, they are also incandescent. But Sat- urn is not an incandescent body. Saturn sheds from her broad disk a very mild re- flected light. And there are indications of a dense atmosphere ; and at the Saturnian poles are indications of snow and ice, which, in turn, Temperature of the Planets. 245 indicate a solid globe and aqueous vapors in its atmosphere. It would seem, then, that the temperature of Saturn cannot differ greatly from that of the earth. Thus in our cosmical equation we have the Saturnian stage = the terrestrial stage. It would seem that Saturn is des- tined to spoil the nebular theory by his in- consistences. He first demonstrates its truth by displaying a series of concentric rings above his equator. Then it is discovered that his rings are an illusion, and the demonstration is worthless. But his friends subsequently dis- cover that the rings are simply granulated, and they take heart from the discovery. But, anon, it is found that his levity is altogether inconsistent with his age. But this is ac- counted for by the supposition, that being so great a body, he has not had time to cool off sufficiently to bring his density to the degree demanded by his relative position ; and, last of all, this supposition is spoiled by the fact that he has a dense atmosphere filled with aqueous vapors, and that his polar regions are icy cold. Moreover, we are thus assured, that remote as he is from the sun, his temperature 246 THE MODERN GENESIS. is dependent on the solar influence ; for if the condition of his atmosphere depended on in- ternal heat, it would be as warm at the poles as at the equator. We see an adjustment of the planet's axis to his orbit, so that a succession of seasons is the result ; we see an axial rotation producing day and night ; we perceive an atmospheric tem- perature adapted to the absorption of aqueous vapors, which the spectroscope assures us are present in it ; we see the indications of atmos- pheric changes similar to those with which we are familiar in the earth ; and we behold the polar regions apparently covered with perpet- ual snow. All these circumstances concur in authorizing the inference that the thermo- metrical condition of Saturn so nearly resem- bles that of the earth that it may be the thea- ter of similar vegetable and animal life, and may also be inhabited by beings whose consti- tution is similar to that of man. From this examination of the indications of the condition of Saturn, and the bearings of them on the credibility of the nebular theory, we pass on to a similar consideration of the Temperature of tJie Planets. 247 condition of Jupiter. " The Jovian Stage" of cosmical history is said to be exemplified by Jupiter. After describing, according to his conception of it, the condition of Mars, Win- eke II says : " When we lift our eyes to Jupiter, lying beyond the populous zone of asteroids, a strongly contrasted scene presents itself. Here are no outlines of continents and oceans, but only a series of changing belts, which are clear- ly phenomena of a medium of great mobility. " It seems to be the general opinion that all we see of Jupiter is a perpetual envelope of clouds. These must float in an atmosphere at a very considerable elevation above the body of the planet, and thus occasion an exagger- ated judgment of its bulk, and a diminished estimate of its density. " How shall we explain this permanent en- velope of watery vapor? The explanation is easy, for this is one of the phases which every planet must present in the progress of its cooling. A time arrives when the upper regions of the atmosphere first at- tain the temperature which condenses the vapor of water. During a cosmic period the clouds accumulate, slowly shutting out the 248 THE MODERN GENESIS. light of the sun, and copiously discharging their rains toward the planet. The rains, pen- etrating the lower strata of the atmosphere, are converted to vapor, and returned to the clouds to be again condensed and precipitated. Every ascending particle of vapor carries off a portion of heat from the atmosphere, and pro- motes the cooling of the planet. But cosmic changes are slow, and ages must elapse while a tempest rages in mid air, which is quite un- felt upon the surface of the planet, save as the vivid lightnings shed a violet gleam over the arid surface, or the rolling thunders mark the time of the tempest's march. Gradually* the line of conflict settles toward the heated crust. At length the rains strike the crust. Then, after a period of increased excitement in the elements, a universal ocean begins to accumu- late a boiling, steaming, turbid ocean. After a further lapse of ages the cooling and accumu- lating waters lead to signs of exhaustion in the clouds. Light filters feebly through, and the lowest organisms appear in the sea. Then the clouds break, and full sunlight and peace- ful elements are the signal for advancing grades of organization. Temperature of the Platiets. 249 " Such a scene has been witnessed in our own planet ; such a storm seems to be raging to-day in the heavens of Jupiter. We gaze upon the shifting shadows of his long-drawn cloud belts ; we imagine the tempest which is raging under their cover, and can almost fancy we see the cloudy mass lit up occasionally by an electric gleam. " Here is a picture of an age long gone by in the history of the earth. Here is a stupen-* dous object-lesson, which, like the curdled fire- mist which engirts the sun, demonstrates an ancient state of terrestrial things, to the knowl- edge of which men could not possibly attain either by history or tradition, or even the un- corroborated testimony of the rocks. " Is it demanded how a planet so ancient as Jupiter can be in this condition, while Mars, earth, and Venus, so much younger, have long since passed their stormy epoch ? We answer, the mass of Jupiter is so great that a larger period must be consumed in his refrigeration. The sun is older than the remotest planet, and has not yet attained even the stage of Jupiter. As Jupiter is a thousand times the volume of the earth, the sun is a thousand times the vol- 250 THE MODERN GENESIS. ume of Jupiter. The ' giant planet ' 'seems hardly to have lost his inherent luminosity. He shines with a stronger light than could be expected, stronger than if his surface were covered with snow. He seems, indeed, to emit, as some think, even more light than he receives. Mars reflects but one fourth the light received from the sun, and the moon but one fifth. Even if, according to others, the light emitted by Jupiter is only three fifths as intense as total reflection of the solar light would render it, this, judging from the reflect- ive capacity of Mars and the moon, implies that half his light is his own. Verily, the clouds must be in the earliest stage of conden- sation about this planet, or the lightnings are really producing such an illumination as in fancy we saw." Geology of the Stars. This is a vivid picture, sketched and colored by an artist of great ability and unbounded enthusiasm. And yet the picture is not en- tirely consistent, for certainly the existence of such an envelope of aqueous vapor as is capa- ble of excluding the light of the sun, is incon- sistent with a condition of luminosity in the planet itself. Clouds that can keep the light Temperature of the Planets. 25 1 of the sun out, can quite as effectually keep the light of an incandescent planetary body in. We make no account of that lively fancy which invests the Jovian lightnings with the power to send their gleams to our earth. That ev- idently was an extravagant playfulness only. If, then, the planet Jupiter is really covered with dense aqueous vapors, it would seem to be conclusive that Jupiter is not sending to us any light that he does not reflect. Now one of two things we will have to do : we shall have to spoil this " stupendous object- lesson " by dissipating these aqueous vapors, or we must* extinguish a portion of that sup- posed excess of light which " implies that half his light is his own." Both suppositions can- not be accepted. Which shall be relinquished ? The true question, stripped of all irrelevant adorning, is simply this: Is Jupiter a self-lu- minous body, or is it not ? Perhaps there is an overestimate of the intensity of the light of Jupiter. Zolner, the distinguished Berlin astronomer and spectroscopist, has recently given much attention to celestial photometry. Employing a photometer of his own invention, by which 252 THE MODERN GENESIS. he avails himself of the polarization of light, he is enabled to reach results of great definite- ness and accuracy. He finds that the inten- sity of light reaching us from Jupiter is only -] as great as that of light reaching us from Venus, T V as great as that of light reaching us from Mars, and j^ as great as that of the light of the moon. But Jupiter is about one thousand six hundred times farther off than the moon, and it would, therefore, require two million five hundred and sixty thousand moons to send us the amount of light from that dis- tance that one moon sends from its present distance, were all shining with their own light. But the disc of Jupiter has one thousand five hundred and forty-five times as much surface as the disc of the moon, and therefore Jupiter ought to give out one thousand five hundred and forty-five times as much light as the moon, and 1,545x700=1,081,500, the number of moons, at the distance of Jupiter, represented by the actual light of the moon. It will be seen, then, that the light which actually reaches us from Jupiter is such as to indicate an orig- inal intensity twice as great as that of the moon. Temperature of the Planets. 253 Does not this imply that half the light of Jupiter is his own? Not at all. When we estimate the amount of light that two convex mirrors will reflect to a given point there are three factors to be considered : 1. Their respective distances from that ob- ject. 2. Their respective reflective powers. 3. Their respective convexities. It is evident that when the mirrors are at dif- ferent distances the reflected rays, which are not parallel, will be scattered over different spaces, and hence, within given spaces, will have different degrees of intensity. It is also evident that if one mirror reflect most of the light that falls on it, and another mirror ab- sorb much of the light that falls on it, the two mirrors will reflect very different degrees of light to the same point. And it must also be evident that if one mirror be very convex, it will scatter most of the light, while a mirror of slight convexity will scatter comparatively little. Now apply these three factors to the case of Jupiter and the moon as reflectors of light. Of the first we have already taken account. 254 THE MODERN GENESIS. Let us look at the second. What kind of sur- face makes the best reflector? Certainly that which is susceptible of the finest polish. But let the matter be full of indentations and pro- jections, let the surface be rough, is it a good reflector? But all observers of the moon con- cur in representing its hither hemisphere as indescribably rough. It certainly is not a re- flector of very high quality. If, on the other hand, Jupiter be enveloped by an atmosphere filled with aqueous vapor, it possesses a good reflective surface. Any one who has ever stood on a mountain and looked down on a lake of fog and witnessed the shimmer of the light reflected therefrom will remember its startling brilliancy. And he who has not seen this, may remember the glow of the cloud in the east made gorgeous by the rays of the set- ting sun. And all have seen the silver edge which the reflected rays of the sun put on the blackest thunder cloud. If the atmosphere of Jupiter is filled with aqueous vapor, we can readily conceive that it must reflect so large a portion of the sun's rays that it should be the most glorious orb visible in the heavens at night. It does not Temperature of ihe Planets. 255 need that we invent for Jupiter any luminos- ity to account for all the light he sends to us. But in our comparison of the moon and Jupi- ter we must not overlook their respective magnitudes. The diameter of Jupiter is eighty- five thousand miles. That of the moon is a little more than two thousand miles. The di- ameters are to each other as forty-two to one. Now a sphere three and a half feet in diam- eter will fairly represent Jupiter, and a sphere one inch in diameter will represent the moon. One half of the larger of these spheres will rep- resent the reflecting surface of Jupiter, and half of the smaller will represent the reflecting surface of the moon. Behold the different de- grees of convexity ! No one, we think, can fail to see that parallel rays of light falling over an area equal to a hemisphere of the moon, on both planets would be reflected very differently by them. The rays that fall on the slightly convex surface of Jupiter would be thrown back in slightly divergent directions. But the rays that fall on the exceedingly con- vex surface of the moon must be dispersed widely in space. In this item of convexity Jupiter has great advantage as a reflector of 256 THE MODERN GENESIS. the sun's light over Venus, Mars, and the moon. To what conclusion do these facts conduct us? Evidently to this: notwithstanding the great distance of Jupiter, his light is not such as implies any thing but reflection. It is of no greater intensity than we have a right to expect it to be, considering his one thousand five hundred and forty-five lunar magnitudes of disc, his slight convexity of reflecting sur- face, and the excellence of his quality as a reflector of light. That Jupiter is wholly opaque is further shown by the transits of Jupiter's moons. We see them not as we see Venus, where she makes a transit across the sun as a dark spot moving across a luminous disc, but as bright bodies, like the planet, yet casting a shadow on its disc as they cross. Moreover, when these same moons pass on the opposite side of Jupiter we sometimes see them eclipsed by the planet. They enter his shadow, and emerge out of his shadow. But while they remain in his shadow there is no sign that he is serving as a sun to them in the slightest degree. Temperature of the Planets. 257 The telescopic features of Jupiter may be briefly enumerated. In the first place it ap- pears to be destitute of continents and seas. If it has any extended, lofty ranges of mount- ains, astronomers have failed to detect them. It appears to be belted with clouds which are arranged parallel with the equator. These belts are sometimes apparently stationary for months, and sometimes they seem to break up, and to spread out over the whole disc of the planet. Astronomers are generally agreed that the belts of Jupiter are phenomena of its atmos- phere. The most convenient hypothesis is that they are " long-drawn cloud-belts," and that Jupiter is enveloped with a veiy deep, dense, and humid atmosphere, and that its very abundant vapors are, by the diurnal rota- tion, drawn out into parallel belts* It would seem to be but a short step to the conclusion that the body of Jupiter must be very hot ; that, in fact, a " universal, boiling, steaming, turbid ocean " is constantly dis- charging its steam into the atmosphere, and that the Jovian stage of planetary history, which is there receiving its exemplification, is a stage in which there is no possible life. A 17 258 THE MODERN GENESIS. modern utilitarian might be pardoned a regret that so much steam power should be wasted. We venture a single suggestion : Is it not pos- sible that the " long-drawn cloud-belts " of Jupiter are an optical illusion? Take an or- dinary twelve-inch globe, and let it be revolved while you examine it. How moderate a mo- tion is sufficient to render the images thereon indistinct, even while you stand over it ! But remove from it twenty or thirty feet, and let its velocity be increased. What do you see ? Continents, islands, mountains, oceans, seas, etc., run together in undistinguishable con- fusion. Even if the mountains were laid on, and the oceans dug out, so that irregularities proportionate to those on our globe were cre- ated, still, as the little globe revolves, what do you see? Do you not see belts? Are they not long drawn ? Are they not parallel to the equator? Even so. And now if you only could manage to get up a half inch of atmos- phere on this artificial globe, and have here and there a half-inch area of vapor floating in it, your long-drawn belts would be cloud-belts, would they not ? Let it be remembered, then, that stupen- Temperature of the Plan:ts. 259 dous as is the volume of Jupiter, its rotation is accomplished in less than ten hours. Thus the surface of Jupiter's equatorial zone sweeps by the observer at the rate of twenty-eight thousand miles an hour. What chance does this rush of the landscape afford for examining its features? Any observation made without a telescope of high power would be futile, for at his great distance from us no details could be made out. But if we could examine it with a power that would bring it apparently as near us as the moon is, the case would be little better, for the rotation would become sensible. This hypothesis is supported by the fact that all the changes of the Jovian aspects consist in a wid- ening and narrowing of the belts. In other words, the observed atmospheric movements are in the direction of the poles. Is it possi- ble that the clouds do not change their places to the east and west ? But if they do, it would not, perhaps, be possible to perceive it. That the changing aspects of the belts indi- cate changes in the relative position of cloud- masses we think not unlikely. Nor would it require a great excess of vapors in the atmos- phere of Jupiter to answer the demands of our 260 THE MODERN GENESIS. hypothesis. There is probably no day in the year when an observer of the earth from Venus or Mars would not see e.xtensive fields of clouds in the earth's atmosphere, and it would not be strange if, as the earth revolves on its axis these fields of cloud should seem to be ar- ranged in belts when there are no belts at all, though they would be moving only at the rate of one thousand miles an hour. And yet there is no universal tempest in the earth. The cloud-belts are all the indication that such a tempest is now " raging in the heavens of Ju- piter." For aught we know the temperature of Jupiter is no higher than that of the earth, and it is sheer assumption to declare that " such a scene has been witnessed on this planet ; such a storm seems to be raging to- day in the heavens of Jupiter." But in the treatment of Jupiter, Winchell institutes a comparison with the sun. He asks : " Is it demanded how a planet so ancient as Jupiter can be in this condition, while Mars, earth, and Venus, so much younger, have long since passed their stormy epoch ? We an- swer: the mass of Jupiter is so great that a larger period must be consumed in his refriger- Temperature of the Planets. 261 ation. The sun is older than the remotest planet, and has not yet attained even the stage of Jupiter. As Jupiter is a thousand times the volume of the earth, the sun is a thousand times the volume of Jupiter." These remarks suggest to us certain questions similar to those we have already raised touching Saturn. It is generally conceded that the density of Jupiter is about one and three eighths, while the den- sity of the sun is one and a half. The sun is the denser body. And yet, according to Win- chell's own reasoning, the planet, being only one thousandth the magnitude of the sun, it ought to have run through its cosmic periods with a thousand times the rapidity of the sun. Why is the earth solid and cold, while Ju- piter is boiling and steaming, and only begin- ning to harden? Why, bless you, that is not a hard question at all ! Jupiter is a very great planet, and the earth is a very little one, and so the " mass of Jupiter is so great that a large period must be consumed in his refrigeration." Well, the sun is a great body, too. It is a thousand times as large as Jupiter, is it not? And since it let Jupiter go out for himself the sun has been cooling off, has he not ? And 262 THE MODERN GENESIS. condensing? He has shrunken away from a magnitude indicated by the orbit of Jupiter himself to the little magnitude of the sun, a body whose diameter is only eight hundred and fifty thousand miles, has he not? You admit this. Well, then, what has this Jupiter been doing all this time? Cooling off! In- deed. And shrinking ! Condensing ! Does not your calculus say that he must have pro- ceeded in this work a thousand times as rap- idly as the sun ? Then how is it that in the matter of condensing he has not even kept pace with the sun ? If the reasoning of Winchell be valid rea- soning on this subject, Jupiter ought now to be hundreds of times as dense as the sun, unless we suppose it to have reached a condition in which its density cannot be increased by its cooling off. In that event the Jovian stage of planetary history would be dismissed, and the occasion would cease on which it could be said : " Here is a picture of an age long gone* by in the history of the earth. Here is a stu- pendous object lesson, which, like the curdled fire-mist which engirts the sun, demonstrates an ancient state of terrestrial things," etc. Temperature of the Planets. 263 All this, in the presence of sober inquiry, seems idle. Worse than idle ! It is little less than charlatan dogmatism introduced into the domain of science. " Curdled fire-mist that engirts the sun ! " Curdled nonsense. If any dependence is to be placed on the revelations of the spectro- scope, the sun is engirt with very rare hydro- gen gas. 264 THE MODERN GENESIS. CHAPTER XIV. PHYSICAL CONDITION OF MARS. Telescopic appearance Red land Green seas Seasons Atmosphere Clouds Average temperature Densities Facts against theories. THE planet Mars revolves around the sun at a mean distance of 139.3 millions of miles. Its diameter is about four thousand three hundred miles, or about twice that of our moon. Its diurnal rotation is accom- plished in twenty-four hours, thirty-seven min- utes, and twenty-two seconds. Its equatorial velocity is, therefore, a little more than five hundred and thirty miles an hour, or about ^ of the equatorial velocity of Jupiter. In several respects Mars is favorably sit- uated for telescopic examination. Both at its conjunction with the sun and at its opposition it turns its illuminated hemisphere toward the earth, and although it passes through some of the phases of the moon, it always shows at least half of its disc enlightened. It is nearest Physical Condition of Mars. 265 the earth at its opposition, and then, like the full moon, shows a full, round disc. Its appar- ent magnitude is about fifty times as great at apposition as at conjunction, which circum- stance renders that the most favorable time to observe it. It is also then in the darkest part of the heavens, and this circumstance gives us the full benefit of the planet's reflection. Unlike the moon, Mars turns all sides suc- cessively to the observer, yet with a motion so deliberate as not to embarrass observation. Mars, to the naked eye, appears the ruddiest of all the heavenly bodies. Under the tel- escope it appears to be variegated, the princi- pal colors being red, green, and white. As- tronomers are generally agreed that the red portions are land, the green portions water, and the white portions, which are chiefly in the polar regions, are snow and ice. The divisions of red and green appear to be constant, as to each other, and so the supposition that they are permanent divisions of land and water seem to be justified. Which are land and which are water have been, and still continue to be, questions on which men speculate. The land may be red or reddish, like the red sand- 266 THE MODERN GENESIS. stone, some of the clays, and much of the feld- spar of the earth. Some have imagined the existence of a Martial vegetation, the principal color of which is red. That even this is possi- ble is evident from the existence on the earth of some species of plants, the stems and leaves of which are red. But, on the other hand, it has not escaped notice that terrestrial waters have been found reddened by infusoria, and it has been thought that the waters of Mars may be reddened in the same manner, and so the red portions of that planet may be water and the green por- tions land. Then we might conceive of the land of that little planet as clothed in a gar- ment of evergreen vegetation. We may never be able to settle these ques- tions. We might conceive that the Author of all things takes such delight in diversifying his works that the phenomena of land and water, and of vegetable and animal life upon that planet, shall be in strong contrast with kin- dred phenomena on the earth. But this is mere speculation. Are there any facts touch- ing the physical constitution of Mars, which have been so well established that they are Physical Condition of Mars. 267 not considered doubtful by the leading astron- omers of our times? Yes. It is not ques- tioned that Mars is constituted of matter exist- ing in the three forms, solid, liquid, and aeri- form. It is chiefly a solid body. But there are bodies of water upon it, and it is sur- rounded by an atmosphere in which aqueous vapors are known to exist. Janssen, of Paris, was at great pains to as- certain the spectrum of light which had passed through aqueous vapor. Afterward he made the planets Mars and Saturn the subject of spectroscopic observation, with special refer- ence to the existence of aqueous vapors in their atmospheres, and he concluded that he had the proof of their existence. Huggins has made the atmosphere of Mars a particular study, and he has found that the vapor of water exists there true vapor of water the same thing chemically as water on the earth. It follows, from these observations, that the average temperature of Mars cannot differ materially from that of the earth. The mass of the seas is fluid water. The temper- ature of the seasons depends on the relations of the polar hemispheres to the sun, and on 268 THE MODERN GENESIS. nothing else. The sun has power to unlock the fastnesses of the ice-bound zones ; to con- vert the snows of winter into the rivulets and brooks and swollen streams of spring and sum- mer ; to lift the aqueous particles out of the liquid state in the seas, and send them, on the wings of the wind, over the continents, where they are permitted to fall in showers of re- freshing. There, as here, .the great motive power is the sunlight, and it is sufficient when Mars is at its aphelion, and it is not in excess when, at his perihelion, he is thirteen millions of miles nearer the sun. While Mars is thus constituted of solid, liquid, and aeriform matter, his specific grav- ity is T Vo- of that of the earth. (Some place the specific gravity at four, water being one.) We have been thus particular to state known features of the physical condition of Mars, be- cause Mars is also a representative planet in the nebular theory. It exemplifies " the Mar- tial stage." The Martial stage is a little in advance of the " terrestrial stage." Life, if it has not all gone out, is not very far from its last gasp in Mars, and the inhabitants of the Physical Condition of Mars. . 269 earth may be assured that when the interior fires give out, the earth, too, will enter the Martial stage, and the final winter will com- mence. It may be some relief to recall Tyn- dall's comforting prediction that the earth will, after freezing up, fall into the sun, when it will certainly be hot enough for awhile. Will the reader pardon this pleasantry ? We will proceed to sober work. In the discussion of the nebular theory in connection with Mars, we again assume as true the pertinent partic- ulars of that theory. That the planetary and solar matter origin- ally existed in a gaseous condition ; that the lighter matter went off in the outer planets ; that all the planets have been cooling off and becoming more dense; and that the present condition of a planet depends, first, on its orig- inal density ; second, on its original volume ; and, third, on its age. If the matter of a planet consist of elements of low specific grav- ity, then, no matter what its age may be, the planet will be light. If the planet consist of all the elements which, in a dissociated gas- eous state, were intermixed so as to make a homogeneous mass, as Sterry Hunt maintains, 270 THE MODERN GENESIS. then the cooling and condensing will be at- tended with a regular increase of the specific gravity of the planet until it reaches the state of liquidity or solidity. If, then, the volume of one planet contracts exactly in the ratio in which the volume of another planet contracts, the densities of the two bodies being equal, each to each at the beginning, they will remain equal each to each through all the periods of their existence. But if the original volume of one planet be twice or any number of times as great as the original volume of another planet, then, their original density being the same, the smaller planet will cool off and condense twice, or such number of times, as fast as the larger planet will cool off and condense. Having assumed these principles as correct, we now beg the reader to accompany us in a careful and sober examination of this question, What ought to be the comparative or relative densities of the earth, the moon, and Mars ? Let us first compare the earth and Mars. If, as maintained by Hunt, the gaseous matter must be homogeneous, then we have the same elements in these three bodies. Mars, how- Physical Condition of Mars. 271 ever, was the first to take his position and de- part on his separate career. And Mars took only about one twenty-six hundred thousandth part of the paternal estate when he left; that is, the cosmical mass which Mars left behind was twenty-six hundred thousand times as great as the mass of Mars itself. Our nebular mathematics conducts us to the conclusion that the condensation of the Martial mass went on from that time twenty-six hundred thou- sand times as fast as the condensation of the parent mass. But in time, we know not how long, the parent mass shrunk to a magnitude indicated by the earth's orbit, and, at this time, it was still a gaseous mass, but its den- sity was almost two and a half times what it was at the birth of Mars. Then the earth was detached, with a density almost two and a half times as great as the original density of Mars. But Mars was now two million six hundred thousand times as dense as at first. Therefore, when the earth began its planetary career, the density of Mars was more than a million times as great as that of the earth- mass. Now can the earth ever overtake Mars? No, not only because of the start which Mars 272 THE MODERN GENESIS. actually had, but also because of the greater fleetness of Mars in the race. Mars is only about one eighth of the mass of the earth, and as to volume at the beginning of this con- temporaneous history, Mars was only the one two million six hundred thousandth of his former self, while the earth was more than a million times larger than he. But as Mars is now only one eighth of the mass of the earth, he will cool off and condense eight times as fast as the earth can, and, therefore, the earth never can overtake him. Never. Even when Mars shall have reached that stage of refrigeration in which the whole mass is solid, if there be any degree of condensation still possible, Mars will progress faster than the earth can. But Mars has not yet reached that stage, and yet the earth has overtaken Mars and passed him in the race. The density of the earth is even now greater than the density of Mars. Mars ought to be frozen up. His seas and oceans ought to be absorbed by the rocks. The Martial stage, according to Winchell, is one a little further advanced than the terres- trial stage. But Mars ought not to be in the Martial stage now, but in the lunar stage, if Physical Condition of Mars. 273 the principles of the nebular theory are appli- cable to him. Mars is, according to the theory, millions of years older than the earth. The earth is other millions of years older than the moon, and yet the moon is, according to the same theory, " a fossil world, an ancient cin- der, suspended in the heavens, once the seat of all the varied activities which now charac- terize the surface of our earth, but in the pres- ent period a realm of silence and stagnation. Sprung from the bosom of the earth, there was a time when its physical condition had not diverged from that of the earth, but swung by itself in the midst of frigid space, and liav- ing but one forty -ninth the bulk of the earth for the conservation of its temperature, cooling pro- ceeded forty-nine times as rapidly as that of the earth. Its geological periods were correspond- ingly shorter." Geology of the Stars. Now we beg the advocates of this theory to adhere to its postulates. Why is the moon now a frozen planet, while the earth, which is its parent, continues internally molten, and is adapted externally for so many forms of life ? Why? The answer is simple. The moon was so little. It was only one forty-ninth as 18 274 THE MODERN GENESIS. large as the earth, and so it cooled off forty- nine times faster than the earth cooled, and that made its " geological periods" (not simply its " cosmic periods," while it was yet a gas- eous body, but its geological periods also, all of them) correspondingly shorter. The lunar geological periods were only one forty-ninth as long as the terrestrial geological periods. Very well. Now will you be so good as to tell us why Mars, which has only about one eighth as much mass as the earth, which at one time was only T o o o o o o as large as the earth, which also is millions of years older than the earth, and which is hung out millions of miles farther in frigid space than the earth, has not yet frozen up? Why can we detect no real difference between the temperature of Mars and the temperature of the earth ? We know of but one reason, and that is, we have no theory to serve by perceiving a difference where there is none, and where there are no signs of any. The mass and volume of Mars being small, and the age of Mars being great, it ought, on the principles of the nebular theory, to be in the condition of the moon, but it is not. It is Physical Condition of Mars. 275 plump and fair, having oceans, seas, and an atmosphere, and showing all the signs of a physical condition similar to that of the earth. Unless both planets have reached the point where their density does not change, the den- sity of Mars ought to be greater than that of the earth. Thus Mars, both in temperature and in density, is an irreconcilable contradic- tion of the nebular theory. 276 THE MODERN GENESIS. CHAPTER XV. PLANETARY MASSES. A SSUMING the truth of the nebular -^*- theory, what will follow touching the relative masses of the planetary bodies ? Shall we find them graduated by any law ? Will they be equal each to each? Will the one first detached be least, and will each succes- sive one be greater? Or will the first be greatest, and will each succeeding one be less than its immediate predecessor? As a philosophical question we will consider not the actual, but the inevitable structure of the planetary system upon the assumption of the postulates of the Nebular Hypothesis and the operation of known physical laws. We must not lose sight of the fact that the theory represents all the cosmical matter at the time of detaching a planetary mass as aeriform, the planetary mass itself as aeri- form, and the elements as dissociated and mixed intimately together. And while one Planetary Masses. 277 class teach that the lighter elements were in the outer portions, another class teach that they were so intermixed that the mass was homogeneous. It must also be borne in mind, that according to the hypothesis, the planetary matter was detached as a peripheral ring, and afterward became a planet. The peripheral ring was detached by the centrifugal force, but how the ring was changed into a planetary mass the advocates of the theory do not try to show. Touching the centrifugal force, we know that it arises out of the rotary mo- tion, and that it may be productive of great effects. But we know also that whenever a body is moved a certain amount of force is exerted. So, also, whenever the direction of the motion of a body is changed a certain amount of force is exerted. We may never be able to deter- mine what amount of force would be requisite to produce the first peripheral ring ; but one thing we may confidently say, that if two bod- ies of the same size and density were revolv- ing in space, then, whatever velocity of rota- tion in one of them would cause the detach- ment of a peripheral ring, exactly the same 278 THE MODERN GENESIS. velocity in the other would also detach a per- ipheral ring. But that is to say that a fixed ratio must exist between the centrifugal force and the quantity of matter which it is able to detach under the same conditions. Against the centrifugal force two other forces are acting. The force of cohesive at- traction, though infinitely feeble, may be said to exist in the gaseous substance. The force of gravity on the peripheral portion of the mass can be estimated by assuming the dis- tance which the periphery was from the center, and assuming the quantity of matter in the mass. But it may also be estimated relatively for any two or more peripheral rings by simply assum- ing the distance. Let G be the force of grav- ity at the distance of Neptune. Then, as this force is inversely as the squares of the distances, it will be at the distance of Uranus, about 3 G ; at the distance of Saturn, 11.5 G; at Ju- piter, 36.9, etc. It will be seen, then, that the centrifugal force will have three times as much gravitative force to overcome a,t the dis- tance of Uranus as at the distance of Nep- tune. At the distance of Saturn it will have Planetary Masses. 279 eleven times as much, and at the distance of Jupiter thirty-six times as much. And this will go on so long as the cosmical mass con- tinues to contract. In each case of ring de- tachment, so much matter as the ring contains will transfer its gravitative influence to the outer regions. If it continue a ring, its pull on the peripheral portion of the mass will be uniform on all sides, and will counteract an equal inward gravitation. But if it be assembled into a planetary mass its pull will be all in one direction, and we may conceive that it will assist in breaking up future rings. But the gravitative force which the mass of Neptune could exert when near the periphery can be only 2-Q*oo-o G, and it will constantly diminish as the mass contracts, so that at the time of the detachment of the Uranian mass it will not exceed T.T^TIT G, an element of influence too minute to greatly affect the results, and we will, therefore, omit further reference to these separate counteracting attractions. We shall see that the centrifugal force, before it could detach matter from the periphery of the rotating sphere assuming that it could detach at all must, in each instance, as we proceed 280 THE MODERN GENESIS. toward the center, overcome a gravitative force several times greater than it overcame in the next preceding instance. And the same thing must be true of density. If the density of the mass will have any modifying power, it will certainly be increased as the mass con- tracts and the density increases. We shall then conceive of the cosmical sphere as rotat- ing with accelerated velocity, until it reaches the point at which the feeble coherency of the substance and the powerful attraction of the mass upon the protuberant equator are over- come by the centrifugal force, and this equa- torial portion is lifted off as a ring. We now conceive of a gradual contraction of the mass, by which its density is made four and a half times as great as at first, and the central grav- itation of the periphery is become three times as great as at first. In thus contracting, the rate of axial rotation has been increased from T ^-UBBARYOr ' ^ u? t I/-" li I i 1 L 007 451 039 7 % I ^ 3a LIBRARY FACILITY AA 000779167 i !l2< S-AHCflfj ii ^ii I i ANCfUi < I