Read Ebook: The Destinies of the Stars by Arrhenius Svante Fries Joens Elias Translator

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Oh, Sin, thou who alone givest light, Thou, who bringest light to men, Thou, who showest favour to the dark-tressed ones, Thy light shines on the firmament, Thy torch illuminates like fire, Thy radiance fills the wide earth. Oh, heavenly Anu, whose insight and wisdom no one comprehends, Thy light is splendid as Shamash, thy firstborn, Before thee prostrate the great gods themselves in the dust For on thee rests the fate of the world.

Anu was god of the heaven and seems here to stand for god in general. Sin was father to the daughter Shamash, who in this hymn already is considered almost comparable to the father. Later on during the Hammurabi-dynasty the Sun, Shamash, was accepted as supreme god, but the Moon remained the regulator of time for religious purposes. For astrological forecasts the priests preferred to use the Moon, and the "signs" in the Moon were the most important. This is true of astrological prophecies also at the time of Tycho Brahe. "Oh, Sin, thou tellest the oracles to the gods who pray them of thee," reads an incantation. From Babylon, the heart of civilization, Moon-worship spread to Arabs and other Semites, and with the Hebrews, as Bergstr?m remarks, the Moon originally played a far greater part than the Sun, although at the time of Christ the condition was reversed. Nevertheless, the Moon has still retained its position as chronographer in the Church Calendar. In Psalms 104:19 we read: "He appointed the Moon for seasons."

On the other hand, no ground worth mentioning supports the theory that the scorching heat of the Sun diminished the peoples' inclination for its worship. On the contrary, homage was generally rendered to phenomena one feared. It is further not true that the Babylonians themselves considered the Sun, Shamash, hostile, the Moon, Sin, friendly. The Sun-god, Shamash, by virtue of his light, was believed to give life and health. The scorching quality of the Sun was attributed to another god, Nergal, prince of the underworld, demon of war and slaughter, source of fever, and, pre-eminently, of plague. No reason existed, therefore, why Shamash should take second rank after Sin, who is said "to carry water and fire," meaning, according to Schrader, that he brought fits of ague and fever. When the Sun after the oppressive day sinks behind the horizon, it is well known that a sharp fall of temperature occurs, particularly in arid zones, but also in humid regions within the tropics where this very phenomenon is utilized for the production of ice. He who exposes himself to the sudden cold of the night falls an easy prey to illness. Particularly is this true under a clear sky--primitive people say "when the Moon shines"--because of the strong radiation. Those who sleep in moonlight are struck by delirium and madness according to primitive thought, an opinion by no means dead among civilized nations--it is common with seafaring men--and is no doubt the origin of the expression: moonstruck . To this belief has probably contributed the fact that epileptic fits frequently possess a period nearly corresponding to the synodical month, which, as I have shown elsewhere, most likely depends on a periodic change in the atmospheric electricity.

In this connection it might also be stated that the third among the great star-deities, Ishtar, the queen of heaven , was the mild but potent, all-merciful sister in every affliction, who delivered from sorcery and illness and gave pardon for sin and guilt. This radiant goddess, who corresponds to the attractive figure of the Catholics' Virgin Mary, was, in spite of her solicitude for the afflictions of men, placed third in the illustrious triad, Sin, Shamash, and Ishtar.

The traveller in the desert is certainly often tortured by the severe drought and a consequent insufferable thirst. This, however, was justly ascribed to the scarcity of water and not to the Sun. The Egyptians, therefore, wished that their departed ones on the journey to their new dwelling-places would meet with refreshing springs where they might quench their thirst and northerly winds that might cool the air. It is well known that the Mohammedans have formed similar conceptions of a paradise in life to come.

In Babylon the local god Marduk, once representative of the planet Jupiter, and among the star-gods ranking next to the three Super-gods, became about 2000 B.C. elevated to the highest position among the gods and assumed at the same time the dignity of Sun-god. It may here be mentioned that Marduk also played a great part as healer of illness. The evolution in ancient Rome followed the same course although at a far later time. Emperor Aurelianus under the influence of oriental Mithras-cult elevated the Sun-god to supreme god of the whole Roman Empire, which then comprised almost the entire known world.

Star-cult was as strongly developed in Mexico as in Babylon. Its main doctrine is stated by Alfredo Chavero thus: "The Father-Creator was Heaven, Xiuhtecutli, or the Azure-blue master. The mother was Omecihuatl, the Milky Way, or the dual mistress." It is well known that a large part of the Milky Way, from the "Swan" to the neighbourhood of the Southern Cross, is divided in two parallel branches, which fact probably is responsible for the title, the "Dual Mistress." "Heaven influenced the Milky Way through fire; from its cosmic matter the stars were set free, the most prominent of which were Tonatiuh, the Sun; Tezcatlipoca, the Moon; and Quetzalcoatl, Venus. These were made the supreme gods. For the purpose of worship, they were symbolized in human shape. Myriads of images, representing these star-gods, were modelled in clay, wood, or stone."

According to this remarkable picture the Mexicans should have arrived at a far better solution of the world-riddle than even the Babylonians did. While most other peoples assumed heaven and earth as the original principles, they gave the high position of progenitress of all to the Milky Way. From her the innumerable stars, with the Sun in the lead, issued. This agrees to a considerable extent with the present conception which we have arrived at during this very last decade, principally thanks to the work of American astronomers. Their investigations have shown how the stars are segregated from the nebulous primeval matter of the Milky Way; how they add distance between themselves and their matrix with age, while simultaneously they develop an increasing individuality.

We have seen that Venus-Ishtar was honoured with membership in the august triad of star-gods, also among the Babylonians. Their successors, the Assyrians, retained the inherited traditions. Thus their kings in the ninth century before Christ symbolized their divine lineage by wearing a necklace with a moon-crescent in the middle, a cross in a ring, emblem of the Sun, on one side, and on the other a star, emblem of Venus . The Jewish synagogues are generally decorated with the star-emblem.

The Mohammedans, like the Jews, utilize the position of the Moon for determination of the Church calendar, and we employ the same means for fixing Easter time. The Mohammedans reckon with a year of 12 synodical months. Twelve such months contain only 354.4 days while a solar year comprises 365.24 days, and as a rule, therefore, the synodical month was rounded to 30 days instead of 29.53 and the solar year to 360 days. Such was the arrangement in Egypt and originally also in Babylon. Primitive men comprehend fractions only with extreme difficulty. In order to correct the discrepancies, odd months were introduced about every sixth year.

From this time we may trace the high reputation of the number twelve. The Zodiac was divided into twelve houses in each of which the Sun was to dwell a month at a time. Day and night were each divided into twelve hours. The circle was divided into 360 degrees corresponding to the number of days of the year, so that the position of the Sun at noon should proceed one degree of the heaven from day to day. As the Moon dominated chronometry, a complication which must have caused considerable confusion was in many places introduced. We have seen that the Australian negroes gave four different names to the Moon in its four different phases. The great change in appearance of the Moon from quarter to quarter makes such a division natural. The synodical month was therefore made to consist of four parts, called weeks. As the length of a month is 29.53 days, the nearest number evenly divisible by four, namely 28, was substituted, and so seven days were allotted to each week, thus introducing an error of not less than 5.5%.

To the establishment of this week the assumption of seven wandering stars has no doubt largely contributed. The priests had discovered that besides Sun, Moon, and Venus, four other stars shift their position on the firmament with reference to the fixed stars, which latter appear always to maintain their relative distances. These four wandering stars were Mercury, Mars, Jupiter, and Saturn. Each day in the week was dedicated to one of the seven wandering stars and received its name. These names have been maintained to the present day, for instance, Sunday, the Sun's day, Monday, the Moon's day, etc. The lunar calendar, established through religious considerations, supplanted the more rational one, which latter, however, survived in Egypt, and was reinstated in the Occident during the French revolution, although unfortunately only for a short time . As a result, the synodical month, in order to suit the calendar, has been changed not only with half a day to thirty days, but also with one and a half days to twenty-eight days. If decades had been adhered to we would have had months of even thirty days and either five leap months of thirty-one days each or half a decade interpolated at new year.

Besides the seven wandering stars known to antiquity , several other stars and constellations played an important part. The Magellanic clouds, considered of evil nature, and the Pleiades appealed already to the Australian negroes. In the northern hemisphere, where the opportunity of observing the Magellanic clouds is small, situated as they are near the South Pole, the Pleiades have attracted the greater attention and the Phoenicians especially appear to have taken interest in this constellation. From them, reverence for the Pleiades spread to a large part of Africa, where we now to our surprise find this star cluster reproduced along with symbols of Sun, Moon, and Venus. Homer also mentions the Pleiades and a few other constellations, namely, the Hyades, Orion, the Great Bear, and the stars Sirius and Arcturus. At all events, the Pleiades have frequently occupied a unique position in the old world. Sirius, the brightest star in the heavens, and Canopus, the second in brightness, also belonging to the southern hemisphere but only half as far removed from the South Pole as Sirius, have both evoked the attention and the worship of the primitive people, in this case the South Africans.

At length, the nations, particularly the Babylonians and the Mexicans, acquired a wider knowledge of the different stars. As the most important ones, Sun, Moon, and Venus, guided the seasons and hence all natural phenomena, a certain mundane significance was naturally ascribed also to the younger ones. Not only seasons, months, days, and hours were each ruled by its star, but so was everything in nature; different winds, provinces, trades, bodily organs, animals, persons, each possessed its star and celestial protector. Comprehensive studies of these correspondences and connections were made and the conclusions were drawn from immaterial semblances and often wholly arbitrarily,--as regards persons from the configuration of the stars at the time of birth. Thus grew an enormously extensive collection of correspondence- and sympathy-doctrines accompanied by a detailed symbolism, an entire quasi-science, which must never be questioned as it originated with the infallible priests. With the Babylonians, religion and science completely melted together and even art was entirely subservient to the same interests. Occasionally the loss of this blissful state draws forth a sigh. Fortunately it is gone never to return.

The oriental wisdom was brought over to Greece and was there amalgamated with the Platonic-Aristotelian philosophy. In this form the Babylonian heritage held sway over the thought of mankind up to less than 200 years ago. The most important branches of this fanciful, so-called science were astrology and alchemy. Tycho Brahe himself made it the object of his life to strengthen astrology by contributing new material to it. Kepler is said not to have believed in astrology but he nevertheless cast horoscopes not only for princes and persons of high position in order to improve his economy, but also for his own family. Probably traces of the old superstition clung to him, and presumably he thought: "If it does no good, neither does it do any harm."

In the same manner, alchemy was carried on by faithful adepts, but more often by impostors, seldom averse to "occult" sciences. Astrologers and alchemists exist even yet among the numerous devotees to occultism; at high price many of them make their predictions or sell their secrets. I have heard a Swedish engineer of very high standing state that their prognostications agreed with events. Among the few alchemists in Europe, most of whom seem to be religious visionaries, Strindberg is of a certain interest to us. Correspondence-theory has played a very large part in the speculations of the learned up to comparatively recent time. It is utilized extensively in the later fantastic writings of Swedenborg. Numerous traces are to be found also in the weakest works of Strindberg.

The renowned French chemist, Berthelot, has given a valuable analysis of the alchemist's method of treating chemical phenomena. His general conclusion is that the false principles which led the alchemists astray revert back to Plato's and Aristotle's philosophical theories regarding the composition of matter. Something similar can be said of astrology. It plays with ideas of its own fabrication with hardly any foundation in reality. The result is almost wholly without value.

The greatest astronomer in Babylon, Kidinnu , constructed tables of great accuracy giving the position of the stars. In this work he utilized observations gathered over thousands of years. These ephemerides were also intended as scripture source for reading the fate of men and for determination of the auspicious moment for the commencement of an undertaking. At all events, they placed great revenue and power over souls in the hands of the ruling priesthood. It does not appear that these priests were able to rise to an attempt of a physical explanation as to the nature of the stellar bodies. That was probably also considered dangerous. The stars were deities composed of purer and more refined matter than found on Earth. It were not improbable that the gods would inflict vengeance on the presumptuous one who dared to intrude upon their secrets and pass judgment on their peculiarities.

Fortunately, there existed in Greece another tendency in philosophy besides the scholastic and the Platonic-Aristotelian. But this was mainly represented in southern Italy, Sicily, and later in Alexandria. Already the followers of Pythagoras had made important progress toward a solution of the stellar problems. The crowning point was reached by Aristarchos from Samos, who lived in Alexandria about 2100 years ago. He established 1700 years before Copernicus the heliocentric system. It is often said that his work was of little value, as Copernicus nevertheless must do it over again. It is then forgotten that Copernicus himself cites the philosophers of antiquity who expressed theories in agreement with the heliocentric system and expressly states that he was bold enough to advance his hypotheses because so many prominent authorities could be mentioned who favoured them. Copernicus did not dare entirely to break away from the Ptolemaic system, and was inconsistent enough partly to use it in his calculations of the motions of the stars.

We have lately advanced farther along the road of Pythagoras and Aristarchos, of Copernicus and Galileo, and we have perfected their methods to a high degree. Progress in astronomy and kindred sciences is nowadays made at a dizzying speed if measured with the standard of antiquity. Occasionally we hear a warning voice asking us to show more deference to a philosophy directly descending from the Platonic-Aristotelian. He who is at all familiar with the history of natural science will understand us when we answer: "We have had more than enough thereof."

That non-naturalists sometimes have a peculiar conception of the present status of astronomy is well illustrated by the statement of one of our foremost theologians in a review of a popular astronomical work where he remarked that the astronomer of today had not advanced much beyond those of ancient time who also could forecast eclipses of the Sun. The predictions were then founded on the recurrences of eclipses after regular intervals much as the new Moons were foretold, with the difference only that the latter occur much more frequently.

Our knowledge of the stellar bodies at present and fifty or sixty years ago are a world apart and the same is true of the latter and that of antiquity. But we must not therefore forget that our brilliant star-science today is derived from men's desire to measure time, and particularly from their need to foresee the food supply in coming days.

THE RIDDLE OF THE MILKY WAY

During dark but starlit nights, the gorgeous firmament is decorated with an irregular band of light that describes a winding path across the heavens. It continues also in the quarters hidden from our sight so that it may be said to surround the firmament like a girdle. This band, which is most luminous in the Northern Hemisphere, is called "The Milky Way." It forms an angle with the equator of about 60? and divides the firmament in two nearly equal parts--the northern, however, is slightly larger.

The literal translation of the Swedish name is "The Wintry Way."

Nevertheless, the human race, until about two hundred years ago, had little conception of the extraordinary importance of the Milky Way. Anaxagoras and Democritos surmised, however, that it consists of a collection of exceedingly minute and densely clustered stars each of which has the nature of our Sun. Ptolemy described, nearly two thousand years ago, its position on the firmament and his observations are valid today as far as determinations with the naked eye suffice. When Galileo introduced the telescope, the conception of the Milky Way as made up of innumerable stars was verified. Not quite two hundred years ago Swedenborg, in his cosmological speculations, considered our solar system as a part of the Galaxy. Wright, Kant, and Lambert further amplified these theories.

The first important forward step was taken by the great William Herschel in his statistical researches. He demonstrated that the stars lie closer to each other the nearer the Milky Way they are located. This is mainly true about the small stars invisible to the naked eye while the more luminous ones are more evenly distributed over the heavens. In certain parts of the Milky Way the stars are over one hundred times more crowded than at its poles--that is, the points farthest removed from the Galaxy. Herschel's investigations were continued and elaborated by Struve, and later by numerous other scientists.

Through these researches, it has been determined that the Milky Way is, so to speak, the foundation upon which the star system, visible to us, is built. All kinds of stellar bodies have been studied and their distribution has proved to be symmetrical with reference to the plane of the Galaxy. The majority is greatly concentrated around the Milky Way. To these belong the new stars which occasionally blaze into existence, as the well-known new star in Perseus, 1901, and nearly all of which have appeared in the Milky Way or in its immediate vicinity. We also find there the irregular nebulae, enormous, vastly diffused volumes of gas, among which the best known is the Orion nebula, and which seem to constitute the primeval matter out of which the stars are born. We might further mention the star-clusters, dense, ball-shaped agglomerations of stars, and the so-called planetary nebulae, which--at least in their visible outer shell--also consist of gas accumulations with a spherical or ellipsoid conformation. The numerous spiral nebulae on the other hand, those strange stellar bodies to which we later shall have occasion to return, are beyond comparison more frequent in the regions surrounding the poles of the Galaxy than in the rest of the heavens.

Many astronomers have considered the Milky Way itself a nebula. The most common theory doubtless is that it closely conforms to a spiral nebula--an opinion that has found a particularly warm advocate in the Dutch astronomer, Easton . A few years ago Prof. Bohlin expressed the view that it is most akin to a planetary nebula, or more precisely to a ring nebula which is supposed to grow out of a planetary ellipsoid nebula by the gaseous matter being driven from its poles toward its equator. It is of a certain interest that this theory lends itself to the support of Swedenborg's--nevertheless improbable--hypothesis about the origin of the planets in the solar system. As we later shall see the Easton conception has the better reasons in its favour.

If classified according to age the stars are again distributed with the Milky Way as a reference point. Thus, let us consider their evolution, which for various reasons is assumed to take the following course. We may commence when the star-matter existed on the nebula stage. It then radiated the light characteristic of certain incandescent gases, principally the lightest two, hydrogen and helium, and further of an otherwise unknown gas called nebulium . These gases were later condensed and dark spectral lines commenced to appear beside the bright lines of the aforesaid gases. Stars on this stage, named after their discoverer Wolf-Rayet stars, occur only in the immediate vicinity of the Milky Way. A later stage in their evolution is represented by the so-called helium stars in whose spectrum the dark helium lines preponderate. They are considerably concentrated around our Galaxy. Somewhat more evenly distributed and yet of decidedly greater frequence in the neighbourhood of the Milky Way, the hydrogen stars appear, characterized by strongly developed hydrogen lines and somewhat retreating helium lines. These stars are more developed than the helium stars and form with them the group of white stars so named after the colour of their light. Next in evolution follow the yellow stars, to which our Sun belongs. Dark metal lines appear in their spectrum. They are more evenly distributed than the groups mentioned before. Still further is this true about the red stars whose spectra contain the characteristic bands of chemical compounds and therefore betray comparatively advanced cooling. They are fairly uniformly spread over the heavens but are still somewhat more numerous in the vicinity of the Milky Way than further therefrom.

These facts are demonstrated in the statistics by E. C. Pickering, Director of the Harvard Observatory, who divided the firmament in four equal zones, the first of which is nearest to the Milky Way and the last of which contains the Galactic poles. His table shows the percentages of different stars in each of the four zones.

The difference is most pronounced in the two first groups; in the three last it is small but unmistakable. An even distribution would correspond to 25 per cent. in all four divisions of the heavens.

These comprehensive statistics, embracing 6106 stars, seem to indicate that the stars in their first stage were within the Milky Way but subsequently drifted away with increasing age. This leads us to the thought that they originated from the irregular, nebulous accumulations which occur in the Milky Way and in its vicinity, or more correctly from similar formations which formerly existed in these regions but which now have clustered into stars. This agrees very well with another observation. With the help of the spectroscope the motion of different stars has been determined with reference to the point where the sun now is. The velocities have been found greater the older the stars are as shown in the table below taken mainly from the investigations of the renowned astronomer, Campbell.

Irregular nebulae 0 Km. per sec. Wolf-Rayet stars 4.5 " " " Helium stars 6.5 " " " Hydrogen stars 11 " " " Yellow stars 15 " " " Red stars 17 " " " Planetary nebulae 25 " " "

To these figures a few remarks founded on recent observations might be made. The average distance between us and the stars in each group is different and the yellow stars, to which indeed our Sun belongs, are those nearest to us in space. They are therefore easier to observe than stars in the other groups. Campbell's statistics include also for this reason a smaller number of stars in this class than in the others. It is conceivable and by the astronomer Halm held to be true that the mean velocity of the smaller stars is greater than that of the larger ones. This is the condition existing in a mixture of different gas molecules, with which the brilliant French scientist, Henri Poincar?, compared the throng of stars, inasmuch as the heavier molecules possess the slower motion. To confirm this W. S. Adams of the Carnegie Observatory on Mount Wilson compared stars of equal velocity in their own orbits. Such stars are considered to be on the average equally far removed from us. He found the theory of Halm confirmed. The mean velocity of the hydrogen stars was reduced from 11 km. to 7.5 km. , that of the yellow stars from 15 km. to 9.2 km. , and that of the red stars from 17 km. to 14 km. , while that of the helium stars remained unchanged. The sequence of the stars arranged according to velocity in the line of sight is evidently not modified by this new calculation.

In regard to the motion of the planetary nebulae it should be mentioned that Campbell in this connection has carried out a great number of new determinations according to which the mean observed velocity of these large bodies in the line of sight must be increased to not less than 42 km. per second.

Campbell and Moore contribute the following interesting data in regard to Nebula N. G. C. 7009 :

"Measures of the rotational velocity of the nebula enable us to draw some interesting conclusions concerning its mass. On the most plausible assumption as to the location of the axis of rotation the orbital speed of the nebular materials lying at a distance of 9 seconds of arc from the centre is about 6 km. per second. If we provisionally assume the mass of the central nucleus to equal that of the Sun, Kepler's law connecting the periodic time with the distance from the nucleus tells us definitely that the nebula is distant from us only 8.9 light years. This must be regarded as an improbably small value, in view of other evidence bearing on the question. For assumed distances of 100 and 1000 light years, which we have reason to believe are more probable orders of nebular distance, the masses of the nebula would be respectively 11.3 and 113 times that of the Sun, and the corresponding periods of rotation 1371 and 13,710 years. From these considerations it seems certain that the mass of the planetary nebula N. G. C. 7009 is several times that of the Sun. The nebula is therefore competent, from the point of view of its mass, to develop into a system more pretentious than is our solar system.

"A few speculations concerning this nebula may not be without interest and value.

"The faint extensions to the east and to the west of the elliptical figure suggest an encircling ring of materials whose principal plane, passing through the nucleus, passes also near our position in space. These extensions terminate in condensed nuclei at equal distances from the nucleus and on exactly opposite sides of the nucleus. The faint extensions and condensations may be and probably are largely the effect of the edgewise projection of such a ring, as in the case of Saturn's rings when the observer is in the plane of the rings. The forms of the two terminating condensations, and especially the wing extending up and out from the east condensation, suggest that we are not precisely in the plane of the assumed ring.

"The form of the main nebula appears to be ellipsoidal and not chiefly elliptical.

"The space immediately surrounding the central nucleus appears to be relatively vacuous. Aside from the nucleus, the principal mass of visible nebulosity exists in the brilliant ring, roughly elliptical as to its inner and outer boundaries, which occupies the region about midway between the nucleus and the outer edge of the nebular structure. The brilliant ring is probably in reality an ellipsoidal shell; the projection of such a shell upon a plane at right angles to the line of sight would naturally show a relatively dark central area, but the projection principle may not be the only one involved.

"If this nebula is in process of development into a solar system, the indications are for a system having certain resemblances to our solar system. Our four outer planets have a combined mass 225 times as great as that of the four inner planets. Similarly in N. G. C. 7009, there is apparently a paucity of material to form planets near the nucleus and an abundance of material for planets at greater distances from the nucleus."

Interesting observations have been presented recently also with reference to the largest among the irregular nebulae, namely the Orion nebula. Three astronomers in Marseilles, Bourget, Fabry, and Buisson, found that parts of this nebula, in the neighbourhood of the so-called trapeze and very close to each other, moved with different velocities and that this difference might amount to 10 km. per second. The south-easterly part approaches us while the north-easterly recedes from us. Consequently a violent whirl-motion undoubtedly takes place in this region. This observation has been verified by the well-known Chicago astronomer, Frost, who employed a different method of investigation than his predecessors. He noted differences in velocity amounting to 11 km. per second between points not over two seconds of arc distant from the trapeze.

If therefore we say that the irregular nebulae on the average possess no motion, this statement does not preclude important local deviations from the rule within the nebulae, intimating a transformation which probably leads to the concentration of the nebulous matter toward the centre of the whirl.

Leaving out, to begin with, the planetary nebulae, it appears that the original matter of the stars stands still in space, that their average velocity increases with increasing age and approaches a mean value of about 18 km. per second or roughly 1000 times the speed of the ordinary passenger train. Our Sun, in particular, moves with a velocity of 20 km. per second toward a point in the constellation Hercules 30 degrees north of the equator.

What force then shall we say it is that causes the motion of the stars? As far as we know none but gravitation. It appears therefore as if the gaseous primeval substance of the stars were not governed by this force. It might prove hazardous, however, to make this assumption as gases also possess weight and even the most rarefied strata of the Earth's atmosphere exert barometric pressure by virtue of their attraction to the mass of the earth. Rather the immobility of the nebulae is due to the frequent collisions between the molecules in any quantity of gas even if it be attenuated to such a high degree as in the nebulae. Thus, the molecules strike a balance, as it were, against each other so that the different parts of the gas accumulations shortly are brought to rest relative to each other. The irregular gas mists around the Milky Way form therefore a continuous whole. A different condition obtains in regard to condensed stellar bodies such as the stars. They may in the densest throng move during billions of years before they collide; but they might on the other hand enter nebulous masses and thereby suffer gradual retardation. We now refer to stars moving outside of the vapour clouds. They are therefore unrestricted and the longer they have obeyed gravitation without impeding encounters with nebulous matter, in other words the longer the time elapsed since they emerged from the gas accumulations which gave them birth, the swifter is their motion. Their velocity can of course not exceed a certain limit which in our parts of the universe appears to be about 18 km. per second. Campbell's measurements show that for the youngest stars the velocity is greatest in the plane of the Milky Way, a natural enough condition as the attracting matter here is most abundant.

The planetary nebulae possess a greater velocity although they, as consisting of mist vapours, are in the first stage of evolution. Faster yet do the spiral nebulae move according to measurements by Wolf of Heidelberg. This shows that they are of a different nature from the irregular nebulae, which form the matrix of the Milky Way. A closer examination of the few--thirteen in all--planetary nebulae, determined by the American astronomer Keeler, convinced me that they approach the Galaxy from its poles with a moderate speed, and subsequently under the influence of its attraction curve their orbit, rapidly gain in velocity, and finally rush into the nearest part of the Milky Way with a very high speed.

A great number of them are no doubt caught in the mists or star-throngs of the Milky Way after exposure to numerous collisions and sweeping away all matter in their course. Such clean-swept traces are very common in the area of the Milky Way. One of the most beautiful examples is the so-called Cocoon nebula in the constellation Cygnus . It has left in its wake a dark rift, in whose bottom, however, exceedingly small and evidently very remote stars are visible according to the German astronomer Wolf .

The great mean velocity of the planetary nebulae indicates that they originally did not belong to the Galactic system, a conclusion also reached by Bohlin, but for other reasons. They are nevertheless more abundant in the neighbourhood of the Milky Way than in other parts of the heavens. This fact, if viewed superficially, might lead to the belief that they are indigenous to the Galactic system, but is explained by their concentration in obedience to gravitation toward the Milky Way.

Quite recently Van Maanen determined the distance of one of these highly interesting celestial bodies, tabulated in the New General Catalogue as No. 7662. Its distance was found to be only about 140 light years. This is about sixteen times the distance of Sirius and the mean distance of a star of the fifth magnitude. This circumstance agrees very well with the idea that this nebula is captured by the Galactic system to which it has approached from very distant parts of the space outside of the Galactic system.

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