Rensselaer Union, Volume 1, Number 47, Rensselaer, Jasper County, 19 August 1869 — THE TOTAL ECLIPSE. [ARTICLE+ILLUSTRATION]

THE TOTAL ECLIPSE.

The Sun—A Sight of lilt Glory during » the Ecliptic—The Cqrona and Protei- ■ berfnors; Their. Size and Character —Theory of the Solar Conatitution. P. Colbert, author of “ Astronomy without a Telescope” and Commercial Editor of the Chicago Tribune, was a mem Imt of the scientific party at D«s Moines, lowa, on the occasion of the recent solar eclipse, and the following descriptive article, taken from the columns of the Tribune «f the 12th insf.,isfrom his pen : The el lipse ot the sun on Saturday last wad visible over all the United States and Territories; but a view of the magnificent corona Which surrounded .the sun was visible only to those who were located on the narrow licit of 156.4 miles in breadth which was swept liy the moon’s shallow. The light of the ’ sun is so powerful and so overshadowing as to shut out the coronal display to those situated only a few yards outside the limits of totality, though they could discern but the merest thread of sunlight at the moment of greatest obscura■tiqn: For the information of those who wi re not privileged to witness the phenomenon by reason of location, as wellasof those who onlv saw it with the naked eve within the band of totality, We herewith present a

view of thecoroiia, as seen at Des Moines, lowa, by the writer, through a telescope, sketclied by him immediately after the total obscuration had passed, and then submitted to several of the scientific observers present, all of whom recognized it as an accurate portraiture. The cut also shows the rose-colored protuberances, the largest of winch were seen by him, but for the smaller ones, and the exact description of all, he is partially indebted to others, who made them the special subjects of observation, while he directed his attention to the corona, during the 17)4 seconds which intervened between the apparent contacts of the eastern and western edges of the luminaries. The circular figure on the accompanying diagram represents the moon, her dark side being turned toward the observer. Though her actual diameter is 394 times less than that of„the sun, yet she is so ’muclTnearer to us that, at the time of the eclipse, her apparent diameter was to that of the sun as 21 to 20, so that the sun was totally obscured durlnglhe 2 minutes seconds required for her to ]>ass over a space equal to one-twentieth part of the sun's diameter. The' apparent motion of her centre was along the line C to D, while the apparent path of the sun’s centre may be represented liy the line B to A, and the direction of the north and south poles of the heavens by the points marked N and S. The letter Z represents the direction of the ; the letters R and L, the direc4ion of right and left. It is evident from the diagram that R was nearly in the direction of northwest; C, nearly northeast, and L, nearly southeast.

That the light-colored rays and the dark rose-colored protuberances (the latter represented by black spots on the diagram) Jiidongedto-thc -sunr-imd-not-te the wni ; is evident from the fact that when the edges of the sun and moon coincided at D, at the first instant of total obscuration, the moon’s edge lapping some distance over the sun at C, the protuberances on the upper left side were visible, and the corona on that side was larger, while, when the moon had advanced so that the edges nearly connected at C, and the moon lapped over at D, the protuberances on the D side were* visible 1 , while those on theC side came into yiew A and the corona on tlie latter side was largest. Accepting this view we obtain a gauge of dimension which enables us to approximately measure the dimensions of the several parts of the corona and the protuberances. Thus.-the sun is known to subtend an actual diameter of 351,736 miles, while his apparent angular diameter at the time of eclipse, was 31 minutes, 37.6 seconds of? space, corresponding to. 442.76 miles to; each second, or very nearly 74,000 tnfiles ' (70,979.76) to each digit, or twelfth part of, the sun’s diameter. But in order to find ; the total amount of projection, it is evident I that we must take into account not only I the amount of protrusion beyond the edge . of the moon, but also the amount due to ' the overlapping of the moon’s edge at the I>oint and instant of observation.

■ - THE CORONA. The corona was Tl-markably different from all preconceived notions on the subject, and from all previous descriptions, both 'in size and shape. Il has always been represented as nearly annular (ring formed), of about equal breadth all the way round the edge of the moon, and not more thap qne-tenth of her apparent diameter. The corona of Saturday last was exceedingly irregular in its outline, and in some places projected to a distance fully ha f that of the apparent,diameter of the moon, or nearly 500,000 miles. Our diagram shows the relative lengths of the several portions, except that on the sides the length is slightly constricted. The greatest length was almost identical with the direction of the moon’s path across the face of the san, which very -nearly coincided with the plane of the ecliptie. From the east side (direction from D) a mass of light shot out to the distance of five or six digits; it was about thirtvdegrees wide at the- base,and aliapeij , nearly like’ the remote half of a SHver poplar leaf. Near the moon it shone with an almost uniform white light, but within a short space it broke up into brilliant I rays, almost parallel with each other, and all pointing nearly towards the centre of the diagram. Still farther pnt these rays assumed more of a streaky character, seeming to lie against a darker backgnind, and towards the summit they ed away into a more diffused and milder ..Jit, though• still distinct and bright.L Near the extremity it appealed nmry like a cumulus cloud, but the central direction of the rays was plainly visible It melted away into the aZure* background almost imperceptibly, but the outline was perfect, except at the “very extremity m the leafsliaped mass. -On the other side of. the disc (direct mp from A, C) was a cojfcs-

ponding tongue, but less regular, and ex tending only-about twju thirds as tar into ths void. This portion was more brilliant Bear the base t han its eounterpart, and was sharply defined at the verv extremity, the rays blending fKithlckly that|t' required a steady gaze to iffmiuta tHn4' The vxtent of this portion wm about mikn. Professor laine saw the light reflected from the moon’s edge nt the distance of 54,000 mites from the sun’s laxly,■'wiille the light was reflected from the Ollier edge at a distance of, 74,000 miles. We compute the total width of the corona in the direction through A D, including the sun’s body, at ■ 1,<100,f)00 miles. Tlie broadest ijMifi qf coronal light was i visible on t|>B left (in Ute wuth east qimr ter). This sprung from an tare oftidxmt Bo degieeson the moorVa circumlcrouce to a height of three digits, -or CB+.OtX) miles. This mass was more diffused than either of 'tffl s othefs, and separated near the extremity Into narrow leaflets of light, something like the (lame from a thinly spread lasl of coals, only there was no red, the light being pure white, with a Cdnt corruscation. < ipposite to this, on the right, wasanother leaf-spread mass of four digits in height, on a base of 20 to 25 degrees, and like a parabola in the general outline, which was, howl-ver, broken up on the outer side into |ets. Another broad sheet sprung up on the/mrth cast (toward the zenith) nearly 1 rectangular iu shtwettmtr ttuee to four

digits high, the upper third part being divided irregularly into tongues of light, formed by assemblages of rays. Between these larger masses the circumference of the lunar orb was filled up by radiate lines of brilliant light, extending on an average a digit and a half in height, of 125,000 miles from the sun’s surface. It was noticeable that this continuous band was the most narrow on the lower left hand side (southwest by south) averaging about two-thirds of the width elsewhere, and was badly broken on its entire outline, as if the regularity were interfered with by the action of the string of bead-like protuberances jutting up through the interior portion of its volume. The full amount of this irregularity was not perceptible with the naked eye, but the general distribution of long and short rays was the same. To the unaided vision the narrower portions of the corona were visible and bright; but the tongue-like extensions faded out into nothingness, whereas the telescope gave a definite out line all around, except at the'summit of the first named protrusion. We do not claim that the relative lengths of the different portions were exactly as laid down here ; they were estimated at the instant, and transferred to paper directly; but the time allowed for observation (less titan three minutes) was so short that it can scarcely, be considered possible to repnxluce every part of the outline with unfailing accuruex. , As stated in the letter from Des Moines, the images of the corona taken in the camera by Dr. Curtis, of the United States Navy, do not show so great a breadth of outline as is here represented, probably for the reason that the light of the outer ixirtions was too faint, by comparison, to fix an image on-t be plate, while the morrbritHan t portions were burning their impress on the apparatus. The photographs show the corona to be least broad in the region of the protuberances, and have preserved the impress of as much of its breadth as corresponds to a distance of 105,000 miles from the-suifs-body, whence we may conclude t lißt the photosphere extends to at least that distance, while the observations of Prof Lane show that at three-fourths of that distance it possesses enough of illuminating power to light up the moon’s surface to an extent-sufficient to cause a reflection of its rays through a distance of 238,000 miles.

A legitimate conclusion from this, and through spectroscopic observations detailed in our reports, is that the solid body of tho sun is surrounded by a self-lumi-nous atmosphere of at least one hundred t thousand tuHes ip thickness, or bne-fourth ■ iiart of his radius, this giving the image ! D.ied in the cambra, and that outside of , the light (photo) sphere is a non-luminous envelope or atmosphere, shining to us by ! means of the light received from the interior shell, which it reflects to our eyes. This non-luminous envelope or atmosphere must be at least 600,000 miles in thickness, and perhaps twice that amount, as its density must decrease with the distance till it joses its reflective power. It is not impossible that the prolongation in the direction CAB, gives rise to the phenomenon known as the Zodiacal light, and rises sufficiently near the orbit of Mercury to cause the disturbances in his movements which have been ascribed to a mythical belt of planetoids.

THE FBOTUBBRANCBA These ate repressnted on the diagram in black ; their ap ph'rent color was a pink red. The instant that the last film of light, with its middle at D, had vanished, leaving the sun in fitter darkness, and simdltaneously with the outflash of the corona, the line of protuberances extending from Pto B also burst updnthe view. The one al the lowest point was the largest. All saw the upper portion, which occupied about 16 degrees on the moon’s disc’, and projected 56,000 miles from the sun’s edge', or fully one-half the average height of the photosphere. Dr. Hilgard saw and described the lower, or pendant portion, 'tfiiifir’was estimated to be 100.000 miles long, by 20,000 miles wide, making a total protrusion of 156,000 miles. The protuberance at L, and the one immediately below it, were also visible to the naked eye; they were rectangular, and were estimated at 20,000 miles high, with bases of five and eight degrees on the circumference. The photograph showed the three more fanci-fully-shaped ones near the eastern quarter, which were also more faint in outline, seeming as if one part lay far behind the other, which crosses it in the diagram. Hence the cross-shaped figure at B was probably made tip of two independent protuberances, the horizontal portion lying several hundred miles farther .from the eye-of the spectator lhan the part which seemed to stand, nearly upright. In tire lower left quarter h* string of bead-like protuberances were also visible with the

aid of the tclescopo. Their comparative size is uect'sxarily exaggerated on our diagram ; they were, perhapa, not more than 5,000 miles high, and dropped out of sight in rapid succession In a few seconds, as tile moon advanced rapidly in the direction Oto I). And now the three larger oiuM at I), B grew smaller, fading from the view about the middle of totality, which fact showed them to have an altitude of about 25,000 miles. At this time the western edge of the moon laid advanced sufficiently in its coirt’se to uncover the protuberances on that side, and the three shown from A to li Hashed on the vision, only the exterior portions being visible at first, but soon growing out farther and farther till the three exhibited an altitude of at least 20, 000 miles, by an aggregate breadth of fully 20 degrees on the base. Meanwhile the protuberance at P grew larger, unsteadily, as the nitsin's edge at that point neared the edge of the sun, but it then seemed to decrease shortly before the total phase ended, showing an actual change in volume, though the character of the outlines did not perceptibly vary. These four were distinctly visible till the last instant, when they vanished with the corona, as a star disappears from view when a flash of lightning illumines the firmament. The spectroscope had already told us that these protuberances are masses of incan descent matter, and some of its constituent elements have been determined to be identical with substances familiar to us, as Iron, sodium, magnesium and hydrogen. But it was reserved to Professor Harkness todiscover that there is a constant decrease in the number of elements in proportion to the height above the sun’s surface. Thus the summit contains no element but hydrogen, and sodium appears a little lower, while iron is, possibly, the element to rise with the greatestdifllculty, and to fallback soonest into the bosom of the sun. We have also reason to believe that these protuberances are identical with the dark masses known as “spots.” when seen on that part of the sun's atmosphere which is between us and his laxly. CONSTITUTION OF THE SUN. So much, then, we know of the constitution of the sun that he is surrounded by a double atmosphere, and that the interior one is self-luminous and the scene of violent changes connected with the formation ami movement of immense bulks of incandescent matter. We know, further, that many of the substances which are found in large quantities on the earth exist also, in the sun, and we may reason from analogy that other yet undiscovered terrene elements join these to make up the grand total of solar matter. But beyond this lies a vast void belonging to the regions of the unknown; probably much that will forever remain “ unknowable ” by mortal. But where knowledge ends speculation begins.

It has been thought that the luminous and non-luminous atmospheres of the sun are like two air strata in our atmosphere; not absolutely separable, nor divided by a line the position of which can be indicated. This is, we believe, the general theory with those who entertain one, that it is but agenerahlistinction, like the discrimination between upper and lower portions of our atmosphere, the one merging into the other by imperceptible gradation, and the self-luminosity ceasing only when the density becomes too small to admit of that intensity of vibration which is supposed necessary to originate the sensation of light. This may- be so, but it seems quite as probable that the sun’s condition is similar, in respect to form, with that of the earth before the continents were upheaved by volcanic force. Then the ocean covered the land, and was itself surrounded by an outer atmosphere of air, the two oceans, then as now, not only balancing each other, but being mutually necessary to the integrity" of character pertaining to each. Of course it is not necessary' that the photosphere should be composed of anything like what we call water,, and indeed we have no particular reason to believe that oxygen, the chief constituent of water, is present at all. But it is necessarily a somewhat dense fluid, and is probably' in a state of more intense motion than any intermovement of particles of which we have any knowledge. There is no doubt thatthisfiuid is also intensely hot, but that is probably not a result of combustion,and is more a consequence of its rapid motion than a necessary condition of heat in the solar rays. So far as we know, light and heat are phenomenal only—mere conditions, not material entities—and these sensations are communicated only by the intermediate vibrations of material particles. It is always cold on the tops of high mountains, though-there be level enough to admit of a large amount of earth radiation, and we must conclude that the difference is principally due toa lessened density of the atmosphere, which presents fewer particles to be vibrated in the passage of the solar rays; hence less of motion; hence less of the sensation of heat. The sun’s rays are warm and light to us only’ because they vibrate through certain media. Take away those media, and the sensation is absent. We have every reason to believe thatthe earth and moon have existed under somewhat similar conditions to those now witnessed in the silt, with this probable difference that the eartji has a conqiarative excess of oxygen, and the sun of hydrogen, while the moon is deficient of both of those elements. To this difference we may perhaps look for consolation against the fear tHiat the sun will be burned out ultimately, and leave our posterity a thousand generations hence to die out of cold. The above view is perfectly consistent, too, with the idea that the sun may be a fit residence for animated beings, organized in adaptation to the situation, and enables us to drop the difficulty which meets us in the attempt to conceive of an eternally self-sustaining conflagration.