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Instead, therefore, of starting with the selves particles of nebulosity in their neighassumption of a "continuous mass of fluid in borhood and engulfing other particles with equilibrium under hydrostatic pressure,” which they come into contact as they acProfessor See starts with the assumption of quire proper motions of their own under a “cloud of cosmic dust. . . a portion of the influence of gravity. He pictures a the universal chaos.” He assumes streams whirlpool nebula, even at a comparatively of this nebulous matter to be drifting hither early stage of its evolution, as containing and thither through space.

an infinite number of these incipient globes, “It is well known that the heavens are each of which is moving under its own defull of streams; for there are streams of veloping momentum and at the same time stars drifting in various directions, and of following the movement of the coiling nebulæ also, but not yet fully investigated. stream to which it belongs. And when (as Now suppose two nebulous streams collide in the comparatively simple case of the while going in opposite directions, or that Solar System) the coiling nebular streams one overtakes the other owing to differences have finally evolved a single central nucleus in their velocities, when moving in the same that is in time to become the sun, the outer general direction. As the two masses ap- portions of the nebula will swarm with proach, their figures will be distorted and globules, globes, moons, and planetoids of curved, so that the streams will tend to varying size, moving in varying directions become entangled. A whirling movement of their own, yet also in the general direcwill follow, each stream wrapping and coil- tion of the original whirlpool; in other ing up on the other. Both streams will words, revolving about the central conremain more or less continuous, and the trolling mass in orbits of every conceivable brightest point will be the place of collision, eccentricity and inclination. where the two streams meet. From this But they will all be moving against the point the two streams will wind off and slight friction of the resisting medium furfinally have their tails projected in opposite nished by the nebulous matter still pervading directions, showing how they approached the entire system. before they coiled up about each other. This is, in reality, the vital point of the This explanation is simple and direct and author's argument. For if a smaller body, follows from well-known mechanical laws. like a planet, approaches a larger body, The winding about the origin usually would like the sun, so that it is caught and held not be perfectly symmetrical; but in gen- within that larger body's sphere of influence, eral, such spirals would be fundamentally its orbit round the larger body (which is double, made up of interwound streams automatically determined by its speed, issuing in opposite directions from the mass, etc., etc.) will never be changed unless nucleus, which is the principal point of con- affected by some outside interference. And, tact. If, instead of two streams meeting as it has always been assumed that the under differences of proper motion, we heavenly bodies moved in a practical vacimagine a single stream of nebulosity which uum, no such external influence sufficient is not perfectly straight left to its own gravi- to account for the gradual reduction of tation—this is about equivalent to separate parabolic and elliptical orbits to circular or streams already in collision-it is clear that near-circular ones has ever been found. in time it will coil up on itself, and grad Note that it was in reality the unquestionually develop into a spiral nebula. Thus it ing belief that the planets move and always makes little difference whether there be must have moved in

practical vacuum one or more streams, united or distinct, the that drove Laplace to seek for a theory of final result is the same, the development of planetary evolution that explained the cira whirlpool nebula.”

cularity of their orbits as an original feature

of their genesis. But it was not a doubt as Professor See contends that in these vast to the effect of such a medium, if one could be masses of nebulous matter, minute centers of postulated, that embarrassed investigators. condensation will sooner or later begin to "The effect of a resisting medium in reform through “the precipitation of ions ducing the major axis and eccentricity of under the influence of X-rays"; and that the orbit of the resisted body is fully recogthese minute centers will gradually increase nized and has been known for more than a in size by accretion-attracting to them- hundred years.

.... As the resisting medium is a vera “On the one hand, this builds up the causa, on the secular effects of which all Sun's mass, while on the other, it clears up mathematicians are agreed, we may hold the inner parts of the nebula. The result that it has as surely rounded up these orbits is that only planets with orbits of large as if we had witnessed the transformation original perihelion distance survive, and within the short period of human history even they have their mean distances and covered by exact observations."

eccentricities greatly reduced. Accord“It will doubtless appear very remark- ingly, we perceive that the surviving planable to future generations,” remarks Pro- ets were formed at a great distance from fessor See, “that we should not earlier have the Sun, or in the outer parts of the solar perceived that the roundness of the orbits nebula.” of the planets and satellites was to be explained by the secular action of a resisting The cosmic panorama of a systematized medium and by no other cause whatever. order evolving out of a nebular chaos that The force and accord of traditional opinion, this volume presents to our minds is so huge however, were so great that for a long time and so difficult to reduce to a summarized no one recognized that a false premise had statement without destroying its impressive entirely vitiated Laplace's original reason- implications of unthinkable time, unimaging. Babinet's criterion” (a mathematical inable space, and indescribable confusion, demonstration of the fact that the solar that we will perhaps do well to take a few nebula never has revolved with sufficient extracts from its author's chapters dealing rapidity to detach the supposed planetary with the presumable history of the Moon rings) “lay buried in the Contes-Rendus, as a guide to our imaginations. and remained unknown to Kelvin, New- “The true mode of origin of the so-called comb, Darwin, Tisserand, Poincarré, and craters on the Moon has long been a matter other modern investigators.'

of discussion. . Nevertheless, it has

been generally held that these craters are So much for the vital point in the author's of volcanic origin. . . . Humboldt remarks argument. We now come to the most strik- with surprise that the central mountains ing feature of the resultant theory, namely, have been found by Schmidt always to lie that instead of the planets being the chil- below the walls by which they are surdren of the Sun, and the satellites the chil- rounded. According to this astronomer's dren of the planets, they are all brothers, investigations, it appears that no single and children of the same nebula. They central-mountain

central-mountain attains the height of are one and all, from the Sun itself to the the wall of its crater, but that in all smallest meteor that is "captured” by the cases it probably lies considerably Earth, survivors of the original nebular below that surface of the Moon from concentrations and 'differ not so much, if which the crater is supposed to have been at all, in age as in the history of their im- erupted. . . . But while the volcanic theory memorial careers. As the author puts it of the Lunar craters is still very generally in one place:

taught in the universities and other schools “We have seen how a nebula grows by of Europe and America, a few sagacious the gathering together of cosmical dust. thinkers have always hesitated to accept Much of this is very fine, but some of it this orthodox interpretation of the most collects into larger nuclei, and thus arise remarkable phenomena presented by the bodies such as the satellites or planets. Moon's surface. In his Popular Astronomy, Now, in an immense nebula the condensa- edition of 1878, Newcomb hints at a new tion goes on at an infinitely great number of theory of the Lunar craters, as follows: centers, and the solid globes thus arising “The Mountains consist, for the most part, are analogous to our Moon. When the of round saucer-shaped elevations, the intelarger of these globes have gathered to- riors being flat, with small conical mounds gether a vast number of moons and united rising here and there. Sometimes there is them into one mass, the result is a planet. a single mound in the center. It is very But in the early history of a nebula, multi- curious that the figures of these inequalities tudes of these moons and planets go into in the Lunar surface can be closely imithe central body to form the governing tated by throwing pebbles upon the surface sun.

of some smooth, plastic mass, as mud or

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mortar." .. We now come to a statement by the wind from the desert, etc. On the of the general theory of the so-called Lunar Moon, however, there is no atmosphere craters, namely, that they are simple sat- sufficiently dense to carry dust, and it must ellitic indentations in a surface of loose and therefore be scattered by impacts and by largely uncemented cosmical dust and frag- direct descent from celestial space. The mentary rock, and not volcanic at all. It fact that the older craters are visibly covis to be remembered that the Moon's grav- ered up is a tangible proof of the important ity is only about one-sixth that of the Earth, part played by cosmical dust in the course and therefore any layer of dust or rock on of ages. . . . It might be asked why, if the Moon would be less settled than on the the Lunar craters are due to the impact of Earth in this proportion; so that the mate- satellites, the Earth does not exhibit batrial would be only very slightly compressed terings and indentations of the same kind. by gravity. Moreover, as there has never We answer that the geological changes on been any water or other fluid on the Moon, the Earth, due to the actions of the oceans except perhaps melted lava in places, there and the atmosphere, have entirely oblithas been no chemical agency which could erated the original indentations of our cement the dust or fragmentary rock into a globe; and since the continents were coherent mass, and it has therefore retained formed, the Earth has suffered no important the form of a loose mass of stony character, collisions with satellites, because the region somewhat analogous to the ashes blown in which it moves was long ago cleared of out of a terrestrial volcano. Falling satel- small bodies. This again indicates that the lites, whether large or small, could therefore conspicuous indentations still visible on our easily indent the surface by compression of Moon probably were made prior to its capthe uncemented material under the force of ture by the Earth; which affords us an imimpact.

pressive illustration of the enormous age * Accordingly, if a satellite fifty miles in of the Solar System. . . . As the Moon diameter collided with the Moon, it would could not at present retain air or water, it is sink down into the soft and uncompacted obvious that it has never had these elesurface, and at the same time be flattened ments. . . . And as our Moon is a captured and spread out at the base. This flattening planet on which surface changes are nearly and basal spreading of the satellite would insensible, owing to the absence of water and make a broad saucer-shaped crater, steepest atmosphere, the study of its well-preserved on the inside and surrounded by more or surface phenomena is of the highest imporless débris driven out and scattered by the tance for throwing light upon the terrific force of the impact, exactly as shown by process of planetary development by the the Lunar craters. In flattening and capture of satellites." spreading at the base, the satellite would force the walls of the crater outward, and According to the Capture Theory, then, itself be reduced to fragments, resting on a the Solar System as we see and know it fluid base, with the highest peak in the to-day is the central portion (Professor See center. This is exactly the aspect pre- estimates that the orbit of Neptune represented by the larger craters. . . . The con- sents perhaps one-thirty-third of the diamsiderable number of craters that are simple eter of the parent nebula) of the original depressions without sensible walls are to be whirlpool nebula, swept, garnished, and explained by the comparative looseness of reduced to order. Each of the planets and the material of the Moon's surface layers satellites has done its part of the sweeping —which allows the mass to yield downward and has had its orbit more or less comwithout throwing up much of a wall about pletely reduced to circularity in the process. the depression produced. . . . The clefts And the result has left the system so nearly are paths cut by glancing satellites, which free from nebulous matter and small partithus leave a straight or curved line, accord- cles that their action as a resisting medium ing to the nature of the surface and the re- has escaped observational recognition. But sistence and rebound. . . . The covering the asteroids survive to testify to the milup of ancient cities on the Earth is due to lions of small planets that formerly whirled deposits of waste, rubbish, and dust trace- about the central nebular mass and later able to meteorological causes connected filled the whole of the present planetary syswith the atmosphere, such as sand borne tem; and one has but to watch the sky for meteors on any summer night to see the it is entirely a matter of chance as to capture of still smaller surviving bodies whether it assumes a direct or a retrograde being consummated and the final sweeping motion about its chosen center. in process being carried on. And when we “But why," we are inclined to ask at this look at the pictures of the battered surface of point, “if this is the case, is it that there the Moon in Professor See's volume, it almost are not as many anti-clock-wise revolutions seems as if we could hear an echo of those in the solar system as clock-wise ones?” titanic impacts, see the turmoil of the re- The answer is absurdly simple. The sulting upheavals, and follow the long and retrograde revolution of a small planet perilous journey of our sidereal companion around the sun, or of a small satellite around from the outer regions of its origin, through a planet is always the result of a special planetoid-filled space and past threatening mix-up between the joint influences of the major planets, to its final surrender to the Sun and the planet as described above. All attraction of the Earth.

bodies captured directly by the Sun and all Of course, this is but the flimsiest and bodies captured directly by the planet are most inadequate outline of Professor See's revolving in the normal direction of the theory as developed in this stupendous original spiral nebula. The occasional volume of his; and it entirely ignores scores retrograde body therefore finds itself movof vital and frequently fascinating problems ing against the stream and is almost certhat he has tackled and disposed of by the tainly destroyed in collision. Only here way. Let us take a look at one of these and there, in the sheltered closed space the problem of the retrograde satellites of about a big planet does a retrograde satelJupiter, the discovery of which threw so lite survive. much doubt upon the validity of the La- And here, perhaps, we might be content placian hypothesis. The author points out to leave the matter; calling attention to that in a system made up of two equal the photographs of spiral nebulæ reprostars, or of two unequal bodies like the Sun duced from the fine plates in Professor and Jupiter, the space about them is divided See's volume, and to the startling eviinto three spheres of gravitational influence, dence they present to us of the actual -one near each body and completely domi- existence and that in every stage of denated by it, and one about both of them velopment-of the stupendous processes together and controlled by them con- here outlined. But to do so would be to jointly. This is graphically illustrated by glimpse but one side of the author's farthe diagram on page 1668. If, now, a reaching speculative grasp. For he has not small body from without enters the joint only reversed and reorganized the Lasphere of influence at a speed that does placean doctrine of the Solar System's mode not enable it to escape, it will begin to re- of development from a nebula, but has volve about both, in an orbit represented by promulgated a logically constructed and the outermost line of the diagram. Later ably defended theory that seems to bring on, under the influence of the resisting into one gigantic and unbroken sequence medium pervading the system, it will drop the most outwardly dissimilar systems of down to the second line of indicated orbit. the stellar universe and even to suggest the Later still, it will drop down to the third possible order of that universe itself. line, then to the fourth, and so on. And He not only traces the double star sysfinally, it will reach a point where, instead tems, disclosed by our telescopes and of traveling round, both it will begin to cut spectroscopes, to an analyzed nebular oria figure eight, circling first one and then the gin; but applies the same theory to the inother. And although, when it first entered finitely complex star clusters that are scatthe system, it was traveling in the same tered along the Milky Way, and argues direction around the Sun as all the other that these huge and powerful centers of bodies of the nebular family—that is to say, gravitational attraction must inevitably be in the direction assumed by the original applying the capture process to independent whirl of the nebular vortex-it only requires stars that approach them in the heaven. a moment's study of the diagram to see that He points to the visible breaking up of when it ultimately abandons its figure eight the Milky Way itself as the result of the orbit and drops down into the closed sphere capture process, carried to its highest power, of influence of either the Sun or of Jupiter, and shows that, if the stellar universe itself is a whirlpool of a higher order, and if our ural philosophers would have answered such sun with its satellites lies at the point indi- a question, had they known that cosmical cated by the bright dot, the exact configura- dust is constantly expelled from the stars tion of the heavens as we see it would be by electric forces and by the radiationexplained.

pressure of their light and driven away And finally, arguing from the demon- from the Milky Way, which they also knew strated repulsive power of light and electric to be composed of small stars too dense to energy upon matter, he concludes that just be seen individually? Can any one doubt as the star systems are developed from that the Athenian sages would have said nebulæ, so the nebulæ themselves are grad- that the nebulæ are formed of cosmical dust ual accumulations of the cosmic matter expelled from the stars, and are therefore expelled by these repulsive forces from the located as far away from the Milky Way stellar systems.

as possible, being collected principally at its “The past ten years have brought to poles? light the most conclusive evidence of the "It is clear that the Physical Universe is prominent part played by the repulsive governed by two antagonistic principles, forces in nature. The delicate laboratory both constantly at work: one being the experiments independently made by Lebe- secular condensation of matter under gravdow, Nichols, and Hull, have established ity to form stars and systems, to be followed the radiation pressure of light on an obser- eventually by another of the opposite charvational basis, and this result has been con- acter; namely, an expulsion of cosmical firmed by the further theoretical researches dust, under electric forces and the radiationof Arrhenius, Schwartzchild, and others. ... pressure of the light of the stars, to form Moreover, the observational researches now nebulæ. ... being made by various astronomers of the "It follows that there is a cyclic process visible repulsion from the Sun of the by which stars and systems arise from matter in the tails of comets, are contin- nebulæ, while nebulæ in turn are formed ually adding specific examples of cosmical from the stars.” repulsion based on the exact measurement and photography of celestial objects. ... It is evident that the Capture Theory If, then, very finely divided matter is con- comes very near to fulfilling the three conditinually being expelled from all well-devel- tions which we have seen that a new scientific oped stars, it manifestly suffices to hypothesis dealing with questions of general imagine these fine particles drifting hither concern must meet. It brings into apparent and thither throughout the universe, and harmony all the outwardly discordant dishere and there forming immense clouds of coveries that have been made since the old cosmical dust. Thus have the nebulæ theory was put forward. It pushes specuarisen."

lative constructiveness far enough ahead to

insure itself a lease of life while its myriad In the illustration on page 1667, we see a implications are being tested. And it gives map of one hemisphere of the heavens. The to the whole mass of these observations and small crosses indicate the position of cata- speculations a dramatic unity that at once logued star clusters. The small dots indicate fires the imagination and satisfies the reason. the position of catalogued nebula. The And meanwhile, that must indeed be an Quaker Meeting arrangement of this celes- earth-bound and unresponsive mind that tial congregation is patent to the most “takes no interest in astronomy” when casual eye. But it requires a See to make astronomy presents to it so vast, so ordered, the following deduction from it:

and so magnificently inspiring a panorama "That this extraordinary distribution of as the one Professor See here opens out for the nebulæ, as far as possible from the stars our contemplation; "enabling an ephemof the Milky Way, has some deep physical eral mortal, dwelling on a tiny planet atsignificance can scarcely be doubted. What tached to a sun of inferior magnitude, to then is the meaning of the observed dis- survey · the uncounted millions of similar tribution? To answer this question in the suns scattered throughout the immensity simplest and most unbiased manner, we of space, and trace the progress of an may ask ourselves how Democritus, Anaxag- orderly development extending over imoras, Aristotle, or any of the Greek nat- measurable eons of time.”

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