Cosmical Problems *

November 16, 1912 SCIENTIFIC AMERICAN SUPPLEMENT 319

Cosmical Problems *

Their Influence on the Development of Spectrum Analysis

By Prof. W olf-Konigstuhl

THE present development of spectrum analysis could general the spectrum depends upon the stability of bution of these absorbing clouds over the sun's disk can not have taken place without its application to cosmical the protuberance becoming more complex with increas be charted. By using different parts of a line, various problems, from which it originally sprung 'and upon ing motion of the latter. A bright line near the sodium levels can be mapped. By using lines peculiar to one which it has grown great. When Wollaston substituted lines especially interested Lockyer because it sometimes solar stratum, such as the chromosphere or the revers the narrow slit for the round hole he was interested in failed to share the displacement which the movement of ing layer, the distribution of this stratum can be the question whether any colors were lacking in the the protuberance impressed upon the hydrogen and studied In this way the four distinct strata have been solar spectrum. When Fraunhofer studied the lines calcium lines in accordance with Doppler's principle; mapped out, both in hydrogen and in calcium. The which bear his name he was thinking not of practical He ascribed this line to an unknown element which he brightest parts of the sun lie above the visible faculle. problems alone, but of the significance of these remark called helium and which remained an astronomical The darkest part are variously distributed over the sur able lines and why the moon gives the same lines as tradition from 1870 until 1895, when Ramsey extracted face and throngh the deepest layers. In the sun spots the sun, while the stars give different lines. The last it from the mineral cleveite. they lie very deep. named fact convinced him that the cause of most of Although direct visual measurement and spectro The discussion of this material has produced a fruit the solar lines lies in the sun and not in our atmos scopic observation gave, in general, according values ful theoretical controversy. According to Jewell, the phere. for the velocity of the eruptive protuberances, the dis principal lines of the solar spectrum resemble those of The discovery of the coincidence of the dark solar placement of the lines often indicated on Doppler's calcium and hydrogen in structure, and the problem lines with the bright lines of laboratory flames sug principle velocities so great that they appeared im ib to determine how far this structure is due to varia gested the researches of Swan, Miller, Stokes, William possible. Julius attempted to explain the displacement tions in pressure and temperature, according to Kirch Thomson, Foucault, Angstrom, and Baulfour Stewart, by anomalous dispersion. hoff's law, and whether it is to be explained by Dop which explained the reversal of the lines, and those of For many years attempts were made in vain to photo pler's principle, or by anomalous dispersion. When Bunsen and Kirchhoff by which the explanation was graph the protuberances, and the first photographs ob white light passes through masses of incandescent completed and the reversal effected in the laboratory. tained were very poor. The correct idea was expressed vapor of varying density, it is extended into a spec Bunsen's researches furnished the foundation of Kirch by Braun, but had been forgotten. Hale of Chicago trum which is irregular and discontinuous. The ab hoff's law, that each element absorbs the same waves and Deslandres of Paris attained the goal by slightly sorption lines are displaced and distorted because the that it emits, a law that enables us to recognize terres different paths. Hale's spectroheliograph is a remark dispersion for these wave lengths varies discontinu trial elements in the sun and stars. Then began the ably fruitful invention and apparently a very simple ously. If this spectrum is viewed through a spectro long laborious and still unfinished series of exact meas one, yet its development to practical utility involved scope whose dispersion is at right angles to its own, urements of the lines of the elements and those of the immense labor. it appears sharply broken at the wave lengths peculiar solar spectrum. The telescope produces a large image of the sun's . to the gas, and shows' narrow bright lines at the bends The question, which solar lines originate in the sun, disk in the plane of a spectroscope slit which admits and broad lines elsewhere. This suggests that the dark and which are added by our atmosphere, was studied a narrow strip of the image. The light of this strip lines may be broadened or reversed by refraction at by means of comparisons of spectra, accurate analyses is extended into a spectrum and falls upon a second points of the sun's disk by overlying masses of gas. of the air, diffe:.:ential measurements interpreted by narrow slit placed immediately over a photographic This possible effect of anomalous dispersion casts doubt Doppler's principle, and observations at high altitude!!. plate. The second slit is placed in the position of one upon the conclusions of Hale and Deslandres, and make Doppler's principle, which enables us to deduce the of the protuberance lines, so that only the light of the it questionable whether the spectroheliograph depicts movement of a source of light from the change in wave protuberances can fall upon the plate. Now the appa the real contour of glowing masses of gas, or repre length, owes its development to its application to the ratus'is set in motion. The first slit moves slowly over sents only the effect of varying density. sun and stars. This principle has revealed to us the the edge of the sun and the second slit moves with Anomalous dispersion varies greatly with wave constitution and extent of the milky way, and has corresponding velocity over the photographic plate. length and the images of the protuberances, if due to given us glimpses of the intimate structure of matter. The result is that the protuberance is photographed by this cause, should vary accordingly; but the protuber The periodic arrangement of lines in the spectral the light of one of its lines. ances at the sun's edge are shown in the same dimen elements has been studied mainly in connection with By this process it is possible to photograph mono sions by every line of hydrogen and calcium. The astronomical researches. IIi this connection the dis chromatically not only the protuberances and the edge anomalous dispersion in the sun may be much greater covery of the second series of hydrogen lines in stellar <6f the sun, but the entire solar disk. Theoretically any than in the laboratory, as Julius suggests. spectra should be mentioned. The determinations of line· of the spectrum, even a dark absorption line, can Another argument against the admission of anoma the temperatures of the sun and stars, formulre of bt, used. Indeed, any part of a line may be employed ous dispersion as a principal factor is the uniform radiation, the researches on the spectra of carbon and thus, according to the theory of the influence of system of distribution of gases at different levels, compounds suggested by the observation of comets, and pressure upon the form of the lines, it is possible to which is shown by all the lines of hydrogen and calcium the first successful quantitative analyses which owe explore the sun at various levels. Finally, Des1andres and many other lines. Additional evidence is furnished their origin to Lockyer's spectroscopic studies of sun has suc.ceeded in applying Doppler's principle to the by the perfect meteorological system of atmospheriC spots are a few of the striking results achieved in the study of the motion of every part of the sun. currents deduced from the Doppler principle. In gen study of cosmical problems. The lines most suitable for use are the lines Hand K, eral, the luminous gases rise in the equatorial zone and The mapping of the solar protuberances and other which are now ascribed to calcium. In the general tbe absorbing gases sink. The spectroheliographic pic features of the sun is a still more striking example. solar spectrum these lines are very broad, dark absorp tures given by every spectral line also show precisely These protuberances were first observed only in total tion bands, while they appear as bright lines in spec the perspective foreshortening of the clouds which their eclipses. The spectroscope was first applied to the trum of the protuberances. geometrical positions on the globe of the sun demand, protuberances in the eclipse of 1868. A spectrum of The bright calciUm lines are found almost every while they can be explained by anomalous dispersion very bright lines, coinciding with the hydrogen lines, where on the solar disk. In many places they yield only when they appear in the center of the disk. was observed. The protuberances, therefore, must be photographs of large cloud-like masses; they are espe The intense. circulation of gases shown by Deslan� masses of incandescent gas rising high above the solar cially strong near the sun spots and faculre. From dl'es' ingenious velocity. recorder is also unfavorable surface. This fact suggested to Janssen the possibility Kirchhoff's law and laboratory experiments it is as to the anomalous dispersion hypothesis.. This velocity of observing the spectrum of the protuberances with sumed that the width of a spectral line increases with recorder is a spectroheliograph in which the two slits out the aid of an eclipse. The protuberances are ordi the density of the incandescent gas which produces it. move not continuously but step by step, producing a narily made invisible by the intense illumination of the This applies also to absorption lines. Hence, it is series of instantaneous views of successive portions of terrestrial atmosphere around the sun's image. In a inferred that the very wide calcium bands H and K the disk, so that the local distortions of the lines can spectroscope of great dispersion this white light is are produced by masses of calcium vapor at great depth be studied. Such series made with the innermost part spread out and weakened without sensibly diminishing and high pressure. In the middle of the wide absorIJ-' of the K line indicate great and regular movements of tht:: monochromatic light of the protuberances. In 1868 tion band lies a relatively bright line which, however, the gaseous masses, and can hardly be explained by the Janssen succeeded in observing the protuberance spec is considerably fainter than the continuous spectrum of slight anomalous dispersion which can occur at this trum at the edge of the sun, and the same result was the sun, and in the middle of this bright line is a very point. obtained almost simultaneously by Lockyer. fine dark line. This fine dark line is attributed to the Especially interesting are the movements of the great By moving the slit of the spectroscope over the tele least dense, highest and coolest calcinm vapor; the dark bands, called filaments, which surround the pole scopic image of the sun's edge the height and extent broad dark band to the deepest, hottest and most dense; like circles of latitude. These bands are invisible to of the protuberances could be determined from the. and the intermediate line to vapor of intermediate posi the eye and are revealed only by the narrow, dark, variation in the length of the lines. Soon Huggins tion, temperature and density. The calcium clouds' of inner part of the spectral lines, as dark masses of gas succeeded, by the use of an absorbing medium,. in see these three levels can be photographed separately by at great altitude. They always exhibit the same move ing the entire protuberances through a widely opened setting the second slit of the spectroheliograph, suc ments and according to Doppler's principle represent slit, while Zoellner and Lockyer obtained the same re cessively, upon the three parts of the K line. This the zones in which the gases rise in all longitudes, in sult by increasing the dispersion, just as one can see result . was first obtained by Hale, Deslandres has re contrast to the equatorial zones of spots and faculre the' whole form of a sodium flame through a train of cently obtained analogous results with the hydrogeIj. where the general motion is downward. prisms without a slit. line. A great variability in the lines of the same element It was discovered that the protuberances sometimes The dark Fraunhofer lines, especially the iron lines, in sun spot spectra was first discovered by Lockyer, rt'sembled vast flames and sometimes clouds floating have also been employed. These lines appear dark by and the discovery has been confirmed by recent obser over the apparent edge ot" the sun. The spectrum varies contrast. Their intensity is weakened by absorption, vations at Mt. Wilson. The simplest explanation is greatly at different times and different parts. Now but they are really thousands of times brighter than given by anomalous dispersion, if we assume that this appear the bright hydrogen and calcium lines, some the light of the full moon and as bright as the glowing is effective near the particular lines of iron or titanium times -with the addition of the lines of helium and vapor which produces the absorption. Hence, any of· that are displaced, distorted, widened or reversed; again the lines of iron and other metals are seen. In these so-called dark lines will produce an image in but in order to make this explanation convincing the the heliospectrograph if the exposure is sufficiently anomalolls dispersion of the gases present must be • An abridgement of an ad dress made before the German long. The slightest variation in brightness, from point Bunsen Society, and published in the Zflit8chri/t lOr Elflktro tested for every wave length in question. Lockyer chflmie. to point of the line is represented, and thus the distri- explained the phenomenon by atomic decomposition.

Another plausible explanation is glven by Lenard's dis of the spectrum. Hence, this expla:!lation was soon It is merely necessary that the print be immersed in covery that the same element emits different lines In abandoned and help was sought In the laboratory. a solution formed of �{ounce of ordinary borax dissolved different parts of the. flaming arc. Among the researches thus suggested were Wilsing's in 6 ou nces of cold water. When the print has black The spectra of the sun spots are exceedingly complex application of Lommell's theory of the damping of ened , it should be removed and washed thoroughly and and puzzling. They show widening of most, but not vibrations by pressure; Humphrey's and Mohler's proof placed in a solution composed of � ounce of gallic all, absorption bands, distortion of many lines, the of the influence' of increased pressure on the displace acid, � ounce of tannic acid and 8 ounces of cold water. presence of lines peculiar to the sun spots, bright re ment of lines, and WilsIng's demonstration of the. In This will intensify the color a.nd make the print parma versals In the middle of absorption lines, the absence CIease of pressure by the generation of electric sparks nent.-The Concrete Age. of fam1l1ar lines, the presence of fluted bands, a depend beneath liquid surfaces. It has been established that ence of the phenomena upon the eleven-year period, increased pressure displaces emission lines toward the Symbiotic, of Yeast Rac - ymbi sis is a and many other peculiarities. Hence, they have sug red, and widens them, to an extent which varies for The LiCe es. S o phenomenon well known to the biologists, this term gested many researches conducted with a view of decid different elements and different wave lengths. Hence, being employed to denote the mode characteristic ing the controversy of anomalous dispersion, versus it seems probable that the birth of a new star is accom of life pairs of species, in which each member of density and the Doppler effect. Two of the most inter panied by immense and periodically fluctuating pres of certain the is more or less dependent upon the other for esting of these researches are due to the initiative of sures produced by tidal action, and that the radiation pm its existence. Numerous this kind are Hale. In one research the widening of the absorption from the external and internal parts alternately pre cases of known the higher animals and plants, but Prof. Van lines of the sun spot was shown, by experiments on ponderates. The nature and cause of the process, how among develde has recently shown that the same kind of the flaming arc and furnace fires, to be probably due ever, are not yet known. When a hydrogen line com effect can be observed in the case of such low organisms chiefly to lowering of temperature, In contradiction to prising a dozen oscillating maxima shall have been as the yeast fungus. He has demonstrated that the Lockyer's views and in accordance with those of Bun produced In the laboratory as it is produced in the joint cultivation tai different races of yeast yields sen and Kirchhoff. This research also proves that new stars, we shlill know more about these bodi!l.s, and of cer n better results than the use either of them separately. many of the puzzling bands are due to the formation also abOut the structure of atoms. of of titanium oxide. These bands, had previously been The other example is that of the very faint nebulro studied carefully by Vogel, In consequence of their which long constituted the most barren field of cos appearance in the spectra of some stars, and had been mical spectrum analysis. In order to obtain photo WE wish to call attention to the fact that we are In a identified in the laboratory by Fowler. The same graphs of their spectra, it is still necessary to employ position to render competent services In every branch rhysicist subsequently traced the sun spot bands in an exposure of 30 or 40 hours, which Involves weeks of ot patent or trade-mark work. Our staff is composed the green to magnesium hydride, and Olmsted proved arduous labor. ot mechanical, electrical and chemical experts, thor that some bands in the red were produced by calcium Soon after the application of spectrum analysis to oughly trained to prepare and prosecute all patent ap hydride. the nebulre, Huggins' succeeded in proving that these plications, irrespective of the complex nature of the The second research was concerned with the fact objects are of two distinct types, the one showing Bubject matter involved, or of the specialized, technical, that many of the greatly widened absorption lines bright line spectra, the other continuous spectra like or scientitlc knowledge required therefor. show bright lines at their centers. We have already the sun's. The nebulre of the first class, therefore, are We are prepared to render opinions as to validity or seen that Julius attempted to explain this phenomena gases and those of the second are star clusters. Little infringement of patents, or with regard to conflicts by anomalous dispersion. Hale's spectroheliographic further progress was made for· many years, but grad arising In trade-mark and unfair competition matters. research indicates a cyclonic motion in the sun spots ually the wave lengths of many bright lines of the We also have associates throughout the world, who and suggests a circulation of ionized gases, which pro- . g!lseous nebulre were determined. These spectra con assist in the prosecution of patent and trade-mark ap duce a magnetic field. t£.in the lines of hydrogen and helium, and also several plications filed in all countries foreign to the United Zeeman discovered in 1896 that the wave length of other lines which cannot be produced in the laboratory. States. light is Influenced by a magnetic field, owing, it is Those of the unknown lines which occur in all nebulre MUNN I; Co., conjectured, to a change in the vibrations of the elec were attributed to an unknown element, nebulium, as Patent Affometll, trons. It was shown that both bright and dark lines certain solar lines had been ascribed to the unknown 361 Broadway, traversing a magnetic field are separated into com helium and the still unknown coronium, both of which New York, N. Y. ponents polarized in different ways. The two limiting are represented also In the spectra of the nebulre. Branch O1Ilce: cases are of especial interest. When the direction of Many attempts have been made to find nebulium in 625 F Street, N. W., a ray is parallel to the magnetic lines of force, the the laboratory, and the hydrogen lines of the nebulre Washington, D.C. Hne is split into two widely separated components, have also been studied diligently. The relative in which are circularly polarized in opposite directions. tensity of these lines differs from that of the hydrogen This is called the longitudinal Zeeman effect. When lines produced in the laboratory. In the nebulre the the ray is perpendicular to the magnetic force, each brightest hydrogen line is the second, in the laboratory spectral line is separated into three lines, lying near it is the first. In seeking an explanation for this SC1ENTIFICAMERICAN together, and each of these lines is plane polarized; the anomaly, Lockyer has endeavored to restrict the hydro middle line in the plane at right angles to the common gen spectrum to the second line by diminishing the SUPPLEMENT plane of the others. The middle line is usually very thickness of the luminous stratum in accordance with Foaacled 1876 weak. This is the transversal Zeeman effect. The the Kirchhoff-Zoellner law. On the other hand Schein NEW YORK, SATURDAY, NOVEMBER 16, 1912 longitudinal effect is produced in a sun spot at the cen er's experiments appear to indicate a physiological ter of the sun's disk where the rays which reach the cause for the apparent difference in the two spectra. Published weeklybyMunn &:Co., Inc. Charles Allen MUDD, President FrederickConvene Beach, Secretaryand Treuurer; earth are parallel to the axis of the cyclone, while the It has also been found that in large nebulre the all at 181 Broadway, New York transverse effect is observed in spots at the edge of intensity of certain lines varies from place to place. the disk, where the rays are nearly perpendicular to ,From this fact conclusions have beeD drawn In regard Entered at the POOIt OIIlce of New York, N. Y., .. Second Cl... llatter Cop7rilrht 1011 by MUDD &:Co •• Inc. the axis. tc: the distribution of matter in the nebulre, and in a In both cases Hale has obtained spectroheliographic similar manner conceptions of the nature of the un Th. Scieati6c Americ:aD PabUcati_ pictures showing precisely the phenomena of separa known elements have been formed. individual lines ScientUlc American Supplement (eat&bliahed 1871). • per YAl' 15.00 tion and polarization that the Zeeman effect demands. which have been attributed to the same unknown ele ScientUlc American (eat&bliahed 1W) • • • • .. .. '.00 Hence, it cannot be doubted that the abnormal widen ment behave differently in the !;Jpectra of different American Homes and GardeIUI • • • • • • • • • '.00 ing of many lines in the sun spot spectra and the ap I'.ebulre. The form of the ring nebula in Lyra, when The combined .ubacription rates and rate. to foreicn countriea includinlr Canada, will befurniahed npon application. parent central reversals are due to the. Zeeman effect photographed through prisms without a slit, shows Remit by JIOIItal or expreumoney order, bankdraft or check of a circulation of electrified particles around the spot, that some of the lines Originate in its interior and and not to anomalous dispersion. MUDD &: Co., Inc.,361 Broadway, New York others in its exterior parts. The same result is shown , The application of the spectroscope to other heavenly by a spectrum photograph' taken with a slit. bodies than the sun has also contributed greatly to J. W. Nicholson first, attempted to compute the The purpose of the Supplement is to publish the development 'Of spectrum analysis. Two examples periods of vibration of the hypothetical element nebu the more important announcements of distin will be briefly mentioned. In the outburst of a new lium, which he pictured as the simplest conceivable star the gu ishe� te chnologists, to digest significant arti light emitted often increases 25,000 times in atom, composed of various numbers of negative elec a few hours. cles that appear in European publications , and In the case of Nova Persei (1001) the trons revolving about one positive electron. The radius light was so intense that the gradual illumination of of such an atom would be, according to Thomson's altogether to reflect the most advanced thought the cosmical dust in the neighboring part of the sky theory, about 3.5 X 1� centimeter. In this way all in science and industry throughout the world. could be observed. The spectral phenomena shown by except two of the lines which had been ascribed to these bodies are As very striking. a rule, a very bright nebulium were calculated. These two are precisely cont;i:nuous spectrum, with its absorption lines, espe those lines which are distinguished from the rest in the Table of Contents cialiy those of calcium, PAOli very sharply defined, is first sl'ectral photographs of the ring nebula. They belong, observed. Unscientill� Food Tests.-By W. T. Sedgwick ...... 306 Soon bright lines appear bordering the most therefore, to other elements. striking Inlluences (}f the Sun's Rays on the Propagation of of these absorption lines on the side toward Nicholson's calculations indicated the existence of a the red end Hertzian Waves ••••- . • . • . . • . • • . • . . • • • • • • • •• • • •• 306 of the spectrum. Every hydrogen line is faint nebulium line which had never been observed, thus bordered. Food Preser�atives and tile Sodium Benzoate Question. The bright lines rapidly widen and but which has subsequently been found in the spectra cever the dark -By J. H. Long ...... 307 lines, while the continuous spectrUm of the nebulre. This discovery of a theoretically com gradually grows Solar and Lunar Halos.-By C. Fitzhugh Talman.-2 fainter. Then periodical phenomena puted spectral line supplies a confirmation of the elec are observed. Ulustrations ...... 308 The lines regularly expand and contract tronic theory similar to that which the discovery of the in a period of a few Approaching the Limit of Increasing