CHAPTER SIX
RETURN OF HALLEY’S COMET IN 1910
“It would have been a gratification to know that everyone who saw this wonderful object, did so with the same feeling of elation and wonder—one would almost say veneration—with which the average astronomer regarded this beautiful and mysterious object stretching its wonderful stream of light across the sky.”
—E. E. BARNARD.
While Halley’s comet, at its return in 1910, was undoubtedly a marvelous object as seen in the clear skies of America and in southern climes, yet it was more or less of a disappointment to watchers of the sky in England, because the view was impaired by twilight and low altitude. Nor did it come up to the expectations of those whose hopes had been aroused by the fine series of ever-varying appearances, recorded by the camera in connection with the Morehouse comet, referred to in the last chapter. Nevertheless, according to Professor Barnard, expert in photography of celestial objects, had it not been for the remarkable phenomena recorded by the camera in connection with the Brooks comet of 1893 (see photograph), and the Morehouse comet of 1908, the numerous photographs obtained of Halley’s comet would have placed it in the first rank among the records of these bodies. Yet while it lacked much of interest as seen with the eye of the sensitive plate, it left a lasting impression on the human eye, adding renewed interest to its long life history of more than two thousand years. The train of the comet reached the prodigious length of 140°, owing to its being so near the earth, and its great curvature was shown by the fact that it remained visible in the morning sky for two days after the head had become visible in the evening sky.
[Illustration:
HALLEY’S COMET
From photograph taken at Union Observatory, Johannesburg, May 5, 1910. Exposure 60 minutes. ]
Halley, by whose name the comet is known, was the first definitely to establish the fact, suspected before, that certain comets are regular visitors to the domain of the sun, returning at stated intervals. For this reason they are termed periodic comets. After Halley had calculated the paths of twenty-four comets, he found that three were moving in orbits almost identical. From this he assumed that the three comets must be one and the same, just as, when a train passes through a station at regular stated intervals, one is led to infer that it must be the same train. Naturally allowances must be made for delays due to fog or stormy weather, but these factors are taken into account should the train arrive after scheduled time. In the case of a comet it may be delayed by means of the disturbing effects of the giant planets Jupiter, Saturn, Uranus, and Neptune, but in Halley’s day the presence of the last two planets in the solar system was as yet unknown (Uranus was discovered in 1781, and Neptune in 1846). Therefore the following prediction made by Halley, when he was convinced that the paths of the comets which appeared in 1531, 1607, and 1682 were identical, is all the more wonderful, since only an approximate allowance had been made for these disturbing factors. Referring to the comet of 1682, he said: “If it should return according to our predictions about the year 1758, impartial posterity will not refuse to acknowledge that this was first discovered by an Englishman.”
This was certainly the most extraordinary prediction ever made, for cometary investigations were then in their infancy, and Halley was the only man living who could have computed the orbit of this comet. Newton had his doubts regarding the suggestion that a comet seen on one side of the sun might be identical with another seen on the other side some weeks later, but Robert Hooke, in a letter addressed to Newton in 1679, suspected that a comet could reappear after a definite period. He declared that, if gravity decreased according to the reciprocal of the square of the distance, the path of a projectile would be an ellipse.
As the year 1758 approached, one can imagine the interest aroused among astronomers, and the calculations which were made for determining as accurately as possible the disturbing effects of the larger planets within the sphere of whose influence the comet might pass. It is impossible to convey an idea of the labor involved in making the required computations of the perturbations of this comet throughout a period of two revolutions, or one hundred and fifty years. It is with a feeling of pride that the author notes the important part taken in this work by Madame Lepaute,[9] wife of one of the assistants of the great mathematician Lalande. Her work proved of inestimable value according to the following remarks made by her husband on the subject:
“During six months we calculated from morning till night, sometimes even at meals; the consequence of which was that I contracted an illness which changed my constitution during the remainder of my life. The assistance rendered by Madame Lepaute was such that without her we never should have dared to undertake the enormous labour with which it was necessary to calculate the distance of each of the two planets, Jupiter and Saturn, from the comet, separately for every degree, for one hundred and fifty years.”
Amid all these difficulties, the computers toiled on, and finally, as the time was drawing near for the return of the comet, Clairaut, who was working in conjunction with Lalande, announced that the expected comet would be delayed one hundred days by the influence of Saturn, and five hundred and eighteen days by the action of Jupiter, and therefore fixed its nearest approach to the sun for April 13th, 1759. These results were presented to the Academy of Sciences on November 14, 1758, and as we have already seen in an earlier chapter of this book, on December 25th of that year the first glimpse of the long-expected wanderer was obtained by George Palitzsch, a farmer of Saxony. His telescope was small, his vision keen, but the enthusiasm of a devoted amateur made up for his lack of suitable equipment. Observations were made of the comet, and astronomers were soon able to prove that the perihelion passage would take place on March 13, 1759, thirty-two days before the epoch calculated by Clairaut. Such a triumphant success of the theory produced a deep impression in the scientific world, and, as Lalande enthusiastically remarked:
“The universe beholds this year the most satisfactory phenomenon ever presented to us by astronomy; an event which, unique until this day, changes our doubts to certainty, and our hypotheses to demonstration.... M. Clairaut asked one month’s grace for the theory; the month’s grace was just sufficient, and the comet has appeared after a period of 586 days longer than the previous time of revolution, and thirty-two days before the time fixed; but what are thirty-two days to an interval of more than 150 years, during only one two-hundredth part of which observations were made, the comet being out of sight all the rest of the time! What are thirty-two days for all the other attractions of the solar system which have not been included; for all the comets, the situations and masses of which are unknown to us; for the resistance of the ethereal medium which we are unable even to estimate, and for all those quantities which of necessity have been neglected in the approximations of the calculation?”
Twenty-five years before the comet was again due, its expected return in 1835 began to arouse the interest of astronomers, and prizes were offered by two academies for the most accurate forecast of its nearest approach to the sun. The successful competitors were Baron Damoiseau and M. Pontecoulant, and several astronomers undertook and completed the task of computing the planetary perturbations. Although the computers, as might be expected, differed slightly as to the time when the comet would make its nearest approach to the sun, yet the difference was not due to any defects in the methods of computation, but to the imperfections of the data employed, especially with regard to the unknown disturbing factor, the planet Neptune.
Not only was the time for the nearest approach of the comet computed, but its exact path among the stars was worked out with such accuracy that directions could be given as to the precise point toward which the telescope must be directed when the comet came within range of observation. On August 5, 1835, when M. Dumouchel, director of the observatory of the Roman College, turned his telescope in the direction indicated and looked through the tube, to his great delight he saw the comet as a faint and almost invisible stain of light on the deep blue of the heavens. Thus did science triumph in a most remarkable manner, the comet making its nearest approach within nine days of the predicted time. It appeared as a nearly circular misty object near to the predicted place, and began to develop a tail about the middle of September, which attained a length of about twenty-four degrees, or nearly five times the distance between the pointers, Alpha and Beta, in the constellation of Ursa Major. To the naked eye the head of the comet resembled a reddish star rather brighter than Antares in the constellation of the Scorpion. Bessel compared it to a blazing coal, and called attention to the peculiar fan-like haze of luminous matter forming the train, which seemed to sway to and fro like a pendulum across the radius vector, an imaginary line joining the sun and the nucleus of the comet. This oscillation took place during a period of four and three-fifths days. He came to the conclusion that a repulsive force about twice as powerful as the attractive force of gravity was responsible for the production of these remarkable effects, thus anticipating the theory according to which the very fine particles forming the train of a comet may be driven away from the direction of the sun by radiation pressure.
Meanwhile Halley’s comet was passing through a remarkable series of transformations, first appearing as a nebula, then as a well-regulated comet with nucleus and train, next shining as a star, and finally dilating till it resembled a ball, then assuming paraboloidal form about May 5, 1836, after which it vanished as if melting into adjacent space through the excessive diffusion of its light. Moreover, it lost its tail previous to its arrival at perihelion on November 16, nor did it begin to recover its elongated shape until more than two months later.
At the return of Halley’s comet in 1910 it was conjectured that it would probably be greatly disturbed by the influence of the planet Jupiter, and that of Uranus and the newly discovered planet Neptune. It was therefore possible for Dr. P. H. Cowell and Dr. A. C. D. Crommelin (both of the Royal Observatory, Greenwich) to make a prediction so exact that the comet was found within six minutes of arc in R. A., and four minutes in declination of its predicted place, as shown on the first photograph obtained. This was equivalent to an angular distance in the sky less than one quarter of the diameter of the moon. (Incidentally, a prize of 1,000 marks, which had been offered by Mr. Lindemann for the most accurate prediction of the comet’s arrival at perihelion, was won and divided between the two mathematicians.) De Pontecoulant had made calculations regarding the return of the comet many years earlier which were fairly near the truth, but one month too late. It was action of Jupiter about the 1835 perihelion that had such an effect on the 1910 return. The action of Jupiter at any return does not produce a notable effect till the following return.
One of the first photographs obtained of Halley’s comet at this return was due to the foresight of Herr Max Wolf of the Heidelberg Observatory, in exposing a photographic plate for several weeks beforehand, so as to entrap the wanderer at the first opportunity. It was caught at 2 A.M. in the morning of September 12, 1909, engraving its image on the photographic plate, a welcome message announcing its advent to the astronomical world. (The first photograph obtained of Halley’s comet was taken at Helwan on August 24, but Herr Wolf was the first to identify the comet’s image on the plate. There were also many early photographs taken at Greenwich.) For thirty-two years it had remained beyond the orbit of the outermost planet Neptune, then, obedient to the attractive power of its lord and master the sun, it had started on the return trip. Despite its enormous distance from our planet, and the fact that it was beyond reach of telescope or camera, it was possible for mathematicians to trace its path with unerring accuracy. It had approached the orbit of Neptune after the year 1888, the orbit of Uranus about ten years later, crossing that of Saturn in 1908. The following year it arrived at the orbit of Jupiter, thus bringing it within the range of both the photographic plate and giant telescopes. Its actual return to perihelion in 1910 differed by two and seven-tenths days from the prediction which can be explained only by the existence of forces which are not pure gravitation, or the possibility of another planet beyond Neptune, as yet undiscovered, acting as a disturbing factor.
When the news of Herr Wolf’s success in obtaining a photograph of the comet had been announced on September 12, it was followed on September 15 by a message from the Lick Observatory to the effect that a photograph of the comet had been obtained by Dr. Heber D. Curtis with the aid of the Crossley reflector. On Wednesday morning, September 15, Professor S. W. Burnham of the Yerkes Observatory at Williams Bay, Wisconsin, sighted Halley’s comet by means of the great refractor with its forty-inch lens, while at the same time it was photographed with the two-foot reflector in an adjacent dome, by Dr. Oliver J. Lee. The comet was again detected by Professor Burnham the following morning, September 16, and it was also registered on the photographic plate by Dr. Lee.
Then came the morning of September 17, one of the most eventful in the life of the writer, who had arrived the previous day as the guest of the Barnards. That night the great refractor with its forty-inch lens was in the care of Professor Barnard, who courteously invited the writer to come to the observatory the next morning at 3 A.M., escorted by his niece, Miss Calvert, for the purpose of looking through the telescope and obtaining a view of Halley’s comet. Making a first visit to the observatory in the darkness preceding dawn was an experience in itself, but the glimpse of the comet after its absence of seventy-five years is one never to be forgotten, nor is it easy to describe. For the first second or so, all seemed darkness as I gazed down the length of that great tube (63½ feet) into the opening beyond. I saw nothing, and an intense feeling of disappointment overwhelmed me as I realized and stated this fact, but Professor Barnard remarked in his whimsical way: “Surely you did not expect to see the comet with a tail?” Then he advised me to keep on looking, and even while he spoke I saw a faint, very misty outline. “Is it exactly in the center of the field of view?” queried Professor Barnard when I told him that I had seen a nebulous-looking object, and when I replied in the negative, he informed me that that faint object I was looking at _was the comet_, which eight months later I saw in all its splendor from the tower at the top of the _Times_ Building in New York City.
Meanwhile, the comet had been slowly increasing in size, and by March 4, 1910, it presented the appearance shown in a remarkable photograph obtained at the Helwan Observatory. It was then suggestive of the nebulous-looking objects which had been catalogued as such by Herschel and Messier, but the latter, being more interested in comets, would soon have recognized, by means of the method already referred to, the difference as the comet slowly moved against the background of the stars. This is no reflection on the marvelous sight of Herschel, but when one reflects on the enthusiasm with which Messier hunted for comets, we may be sure any suspicious-looking object he came across was subjected to keen scrutiny before it was catalogued finally as one of those “embarrassing objects” he named “nebulæ.” During the autumn of 1909 and the early part of the year 1910 the comet was photographed and observed visually at all the great observatories. At the Royal Observatory, Greenwich, a fine series of photographs were obtained despite the trying climate of our country. Up on the heights, at the Government Observatory at Kodaikanal in southern India, the progress of the comet was recorded by telescope and camera, so that our planet might be said on this occasion to have kept its Argus eye constantly directed toward the celestial visitant.
According to Professor Barnard, who made a special study of the comet, its first appearance resembled that of a small and rather faint speck of light, very much like a faint stellar nebula. The increase in brightness was not very rapid, and as late as the final observations in February, 1910, before the comet passed behind the sun, it gave very little promise of the splendid display it was destined to make later on in the month of May. However, its reappearance from behind the sun in the morning skies of April and May could not have been under more unfortunate circumstances for observation at the Yerkes Observatory. According to Professor Barnard:
“that part of the year is always unpropitious here, and it seemed as if everything combined, on this particular occasion, to hide from us the growth of the comet and its approach to the earth. Forest fires in the northern part of the State (Wisconsin) produced a densely smoky sky, which, even when the clouds were merciful to us and would have let us see the comet, cut off with a thick yellow veil all but a glimpse of the bright head.”
The comet was seen for the first time with the naked eye at the Yerkes Observatory on April 29, the nucleus being bright and of the second magnitude. The tail was visible for a couple of degrees, but with field-glasses it could be traced for four or five degrees. On May 3, at 3 h. 40 m. (civil time), the comet was seen for about one minute in a thin streak of clearer sky, but the next morning at about the same hour it was a beautiful object with a long tail streaming upward toward the right, as shown on the magnificent photograph obtained by Professor Barnard. The photograph facing Chapter VI, taken at the Union Observatory, Johannesburg, on May 5, 1910, may give some idea of what was expected but not realized by watchers of the sky in England.
When it was announced on April 29 that the comet had come within range of naked-eye observations, it occurred to the writer, who was in New York City at the time, that a desperate attempt must be made to see the comet, despite the smoke, and electric lights turning night into day. “When there’s a will there’s a way,” and while walking along Broadway on the afternoon of April 30, wondering how these difficulties might be overcome, a glance in the direction of the _Times_ Building solved the problem. On explaining to Mr. Van Anda, the assistant editor of the _Times_, what a very desirable spot the summit of the _Times_ Building would be for observing the comet, a permit was obtained to be handed to the janitor the next morning at 3 A.M. on May day. It was indeed a case of “Call me early, mother dear,” but an alarm clock served the purpose equally well on this momentous occasion.
Promptly at three o’clock the permit was presented to the janitor, and the writer, ascending in the lift, was transported to the twenty-third story, and escorted up a spiral staircase leading to the tower. The door was unlocked by the janitor, and the writer, stepping out on to the parapet surrounding the tower, gazed eastward for the comet, which failed to materialize, owing to a dense haze. Awaiting until dawn, the idea of seeing the comet was given up, but, nothing daunted, the same program was carried out at the same hour on May 2, and May 3, but without avail.
[Illustration:
HALLEY’S COMET
Photograph taken on May 4, 1910, by Professor E. E. Barnard at the Yerkes Observatory, Williams Bay, Wisconsin ]
Then came May 4, a bitterly cold morning; but the stars shone brightly and there was every hope of the comet being visible from the tower heights. These hopes were confirmed, for on stepping out on to the parapet the writer saw the comet in all its splendor. The hazy-looking object seen on September 17, 1909, had developed into a full-grown comet with a head shining as a star of about the second magnitude, and surrounded by a nucleus. Extending outward like the beam of a searchlight gleamed the tail nearly fifteen degrees in length. Calling down to the janitor to make known the good news, the balcony was soon filled with eager members of the _Times_ staff, who were thus enabled to obtain a view of the comet. By means of a field-glass thoughtfully provided by Mr. Van Anda, it was possible to see a further extension of the train, making it in all thirty degrees in length. Spurts of light like tiny waves seemed to flow out from the nucleus to a distance of two or three degrees. At twenty minutes to four, the writer, on looking downward at the horizon, was startled by what appeared to be a streak of flame, but as it rose higher it proved to be the crescent moon, which with the comet and the planet Venus, completed a wonderful trio. The comet remained visible, resembling a bright star with a slender stream of silvery mist trailing a few degrees after. By four o’clock it had faded in the light of approaching dawn. A glance at the photograph of Halley’s comet obtained by Professor Barnard at the Yerkes Observatory on May 4 will give an idea of its splendor.
For the next few mornings observations of the comet were disappointing, owing to heavy mists in the eastern skies. The comet was almost completely hidden from view, except on the morning of May 8, when occasional glimpses were obtained of it through rifts in the clouds. On May 10, the nucleus of the comet, from which extended a diminutive train eight degrees in length and fan-like in appearance, could be seen for a few brief moments, after which it remained hidden behind clouds until dawn, making further observations impossible.
It was not until the morning of Friday, May 13, that the comet once more deigned to reveal itself to the straining eyes of the lonely watcher on the tower. The first glimpse was obtained at ten minutes past three. The comet then resembled a faint white streak drifting in the sky. A minute or so later the planet Venus came into view, gaining in brilliancy as it rose above the mists near the horizon. At twenty-five minutes past three the train of the comet was twenty degrees in length, and by half past three it extended to a distance of thirty-five degrees, or seven times the distance between the pointers (Alpha and Beta in Ursa Major). It spread out like a partly opened fan, its greatest width at the extreme end being about five degrees or more. The nucleus shone brightly as a star of the second magnitude, but by half past three it began to grow less distinct, and at twenty minutes past four the comet had faded from view on the arrival of the first few streaks of dawn.
The comet was barely visible the next few mornings, though watched for anxiously, since there was always the possibility that it might reveal itself, but these hopes were not realized. A glance at the cloudy skies on the morning of May 18 suggested the impossibility of seeing the comet, and for the first time since the morning of May 1, the writer missed her vigil at the tower.
Interest was revived, however, on learning that Professor Barnard had seen that morning
“a narrow twilight (which later proved to be the tail of the comet) which seemed to extend along the eastern horizon.... The head of the comet could not be seen when it rose, with either the five-inch or the forty-inch telescope, because of the thick sky near the horizon.... The observations show that the tail was at least 109° long on that date. (_Astrophysical Journal_, vol. XXXIX, no 5, pp. 387–388, June, 1914.)
Now despite the fact that an astronomer at Columbia University had declared the comet would be in the evening sky, and it was useless looking for it in the morning sky of May 19, the writer decided, nevertheless, to watch for the comet at about the usual hour, and with the most gratifying results.
The parapet surrounding the tower was crowded to its utmost capacity by a favored few on the eventful evening of May 18, awaiting they knew not what, for a report had gone forth that we were scheduled to pass through the train of the comet. Below us we could see comet parties in progress on the roof gardens of some of the leading hotels. Sounds of merriment occasionally reached us, but by half past ten we—that is, Miss L., who had offered to share the lonely vigil with the writer until dawn—were the only watchers on the tower. The hush of a great silence had gradually fallen over the city, and in silence, too, we watched the eastern sky for any further trace of the comet.
Notes made by the writer on this occasion record 11.10, red flash (auroral); 11.22, flash resembling an arch of glowing white surmounted by a crest of crimson. The display occurred above a low-lying bank of mist and rose to about five degrees above the horizon. It was not of any considerable breadth, and resembled rather a glow of color against the dark background of the sky than a wide band of light. The moon, which was shining brightly, interfered seriously with the observations of auroral displays which appeared faint in its light. About 12.15 a mist appeared to spread over the city, and the air had become damp and chilly. By 1.30 the mist had cleared away. At 2 o’clock a meteor flashed across the eastern sky, downward in the direction of the star Gamma in the constellation Pegasus. It was bluish-green in color, pear-shaped in appearance, leaving a streak five degrees in length behind it as it flashed to within ten degrees above the horizon. It remained visible for about five seconds, and the display was vivid while it lasted. At 2.30 the moon, low down in the western sky, appeared of a ruddy hue as it “sank in a sea of gloom.”
Turning eastward, we saw a soft glow in the sky spreading from below Pegasus and upward as far as the stars of Cassiopeia. At 2.34 a glow of grayish hue extended over the northeastern sky. At 2.43 a bright meteor was seen by Miss L., but she made no note of its direction, except that it was eastward, and a brief glimpse obtained by the writer showed its color as bluish.
At 2.45 streamers, which later proved to be the comet, were observed reaching from the eastern horizon, below Gamma Pegasi, and curving upward through Aquarius as far as Altair, and brighter in appearance than the Milky Way. At its widest part, just beneath the first-magnitude star Altair, the width of the band was about ten degrees, and throughout its length it had a brilliancy equal to that of the Milky Way, near which it terminated. The path of this band of light was very nearly that along which the comet was last seen, and the writer was convinced that it was the outer boundary of the tail through which the earth was passing. Beneath this streamer, and apparently resting along the southeastern horizon, was a secondary band resembling a haze-like misty streamer. This was not as clearly defined as was the upper band, and, moreover, it merged into the mists of the horizon.
In connection with a sketch made by the writer on this occasion, and shown to Professor Barnard, he referred to it as follows in his account of “Visual Observations of Halley’s Comet in 1910,” published in the _Astrophysical Journal_ for June, 1914:
“With the exception of a sketch by Miss Mary Proctor in New York City, and a newspaper account by Professor D. P. Todd of Amherst (whose observation seemed to refer to May 16th), I have seen no reference from northern observers to the second, fainter and broader tail shown in my drawings of May 17 and 18, south of the bright beam and separated from it by a distinct dark space, perhaps ten degrees wide. The head of the comet was of course invisible, being below the horizon.”
This was all the more pleasing to the writer, as doubts had been expressed in no uncertain terms by a well-known authority, according to the following statement published in an afternoon paper. “Some one thinks she saw the comet in the eastern sky, when it is really in the west.” One can imagine the anxious time experienced while awaiting confirmation of the observation, but it came in due course from Yerkes, Lick, Argentine Republic, South Africa, and the writer felt rewarded for the many dreary waits in the tower during the “wee sma’ hours” since May 1.
On the morning of May 20, the writer again watched from the _Times_ tower, in the hope of seeing some straggling streamers trailing along the sky, denoting the presence of the comet. Between half past two and a quarter past three a ghostly apparition resembling a slender band of light was seen extending upward, though almost parallel with the northeastern horizon. It seemed to rest on a darker band of luminous haze beneath. Surely this was the last fragment of the train of the comet, outlined faintly against the dark void of space.
That same morning Professor Barnard at Yerkes detected a hazy luminous streak about five degrees broad extending from Aquilæ to the east and onward toward Alpha Pegasi. “This resembled the comet’s tail,” recorded Professor Barnard,
“but was doubtless a strip of haze. I looked at it several times, taking it for a strip of haze, but it did not seem to move. There were masses of moving haze overhead toward the north. To all appearance it looked like the comet’s tail of the mornings of May 18 and 19. I cannot be certain that it was not haze, but it was a singular coincidence of position, appearance, etc., if it was. It remained visible for fully fifteen or twenty minutes.”
[Illustration:
COMET 1861, JULY 2, AS SEEN AND DRAWN BY R. A. PROCTOR
The tail of the comet was near the earth, which passed through it on this occasion ]
The train may have been fan-like, as in the case of the comet of 1861, discovered on May 13, by Mr. John Tebbutt of Windsor, New South Wales, already referred to in the chapter on “Comet-hunting as a Hobby.” In my father’s book, _Mysteries of Time and Space_, he records as follows his view of that comet in connection with the drawing here given:
“The first recorded observations (of the comet of 1861, in Europe) were made on the evening of June 30, nineteen days after it had passed its point of nearest approach to the sun. I remember well observing it on the morning of July 2, 1861. For some reason I found it impossible to sleep that morning, and getting up about three (the exact hour I do not remember, but it must have been very early), I saw in the east what looked at first like the rays of an aurora borealis. But presently I noticed that these rays proceeded (unlike those of the aurora) from a bright center, which had been hidden by clouds when my observations began. I used at that time to keep a four-inch telescope, mounted on a three-legged stand, in my bedroom. This I had quickly ready for action (noting that the object, owing to the approach of sunrise, was getting fainter every minute), and turning it on the comet, I drew a picture of the nucleus and coma, so closely resembling that which appeared a week or two later in the _Illustrated London News_, that I might have supposed my picture had been surreptitiously sent to the office of the _Illustrated_, had I not found it resting just where I had put it in my scientific portfolio.”
Returning to the discussion of Halley’s comet, it was seen on May 21, at 4.30 A.M., by Professor Evershed, (then director of the Kodaikanal Observatory, Southern India), appearing no broader than on May 18, but fainter. He described it as passing centrally through the square of Pegasus, which was nearly filled with the faint light. The tail could be traced, as before, right up to the Milky Way. The star ε Pegasi was nearly in the center of the band of light, and the star α Aquilæ near its southern edge. This was the last observation Professor Evershed made before dawn. He considered it remarkable that the tail of the comet should have remained visible in the morning sky as a narrow band of light, nearly two days after the head of the comet had passed to the other side of the sun. He suggested that this might be due to the fact that the tail may have been strongly curved and very broad in the direction of the comet’s motion, although narrow and straight in the direction at right angles thereto. If so, the passage of the earth through the tail, if it occurred at all, must have been delayed one or two days and probably occupied more time than a single day. There is some doubt whether the tail did actually touch the earth, for observations of its position in the sky on May 11 and 15 show that its axis was inclined very considerably northward from the direction of the radius vector, a straight line drawn from the nucleus of the comet to the sun of the comet.
In the forenoon of May 19 certain peculiarities observed suggested that our planet may have been actually immersed in the cometary débris of the train of Halley’s comet. These consisted of a peculiar iridescence and unnatural appearance of the clouds near the sun, and a bar of prismatic colors on the clouds in the south. This, combined with the general effect of the sky and clouds—for the entire sky had a most unnatural and wild look—would have attracted marked attention at any other time than when one was looking, as on this occasion, for something out of the ordinary. According to the observations made by Professor Barnard at the Yerkes Observatory, the sky had been watched carefully during the forenoon of this date, but nothing unusual had appeared until close to noon, when the conditions became abnormal. Later on in June, and for at least a year afterward, slowly moving strips and masses of luminous haze were observed in the sky, which were not confined to any one part. Reports of like unusual phenomena were received from the Transvaal, and from elsewhere in southern climes.
On the evening of May 21 the comet made its first appearance in the west, as seen by watchers on the _Times_ tower, but it failed to be very impressive. It was to the left and a few degrees north of the star Betelgeuse in the constellation of Orion, and it resembled a star of the third magnitude. It was surrounded by a hazy cloud-like mist that made it appear nearly as large as the space covered by the moon. To the left of it, and extending outward about three or four degrees, were three or four fan-like streamers. At 8.25 the nucleus seemed brighter and more star-like in the center, but the streamers had faded from view and the mist surrounding the nucleus had become hazy and ill-defined. Five minutes later only the star-like nucleus could be seen, doubtless owing to the combination of the glare of moonlight and the haze that reflected the city lights below.
On May 24 the comet appeared hovering for a brief interval over the western horizon, resembling a faint star enveloped in mist, and adorned with a short fan-like tail. On May 25 the comet could not be seen, owing to the mist and a drizzling rain, but on May 26 it was visible on two occasions for intervals of about five minutes. It then resembled a fairly bright star of the third magnitude, surrounded by a misty halo, but was devoid of a tail. It seemed that our chances of seeing the comet again under favorable conditions were slight, but on the evening of May 27 we were once more regaled with a fine view, which proved to be final as far as the writer was concerned.
At a few minutes past eight the nucleus of the comet appeared, as usual, hazy and ill-defined, but gradually it brightened until it equaled the glow of the first-magnitude star Regulus, in the constellation of Leo near by. Only a few degrees of tail were visible at first, but as the twilight deepened into night more and more came into view. By 8.40 P.M. it stretched outward about twenty degrees in the direction of the planet Jupiter. The train was long and slender, and not more than five degrees at its greatest width. By 9 o’clock it was clearly visible, a dark streak apparently dividing it just beyond the nucleus; the edges were more or less sharply defined for a distance of about three or four degrees. By 10.30 the train of the comet had almost faded from view; at 10.40 it had become invisible and the nucleus was barely perceptible. Within three minutes the nucleus was almost lost to sight in the haze and mist near the horizon.
Meanwhile, the moon had risen in the eastern sky, and by eleven o’clock it was several degrees above the horizon. Its arrival on the scene was the climax of an evening rich in glory, as far as the celestial display was concerned. The view of the comet on this occasion was the best that had been obtained since May 20, and settled beyond doubt the vexed question that had arisen as to whether the comet had lost its tail or had divided in two. Nevertheless, a glance at a photograph taken by Professor Barnard on June 6, shows an apparently smaller comet nestling to the left of the larger, keeping it company, as it were, in its celestial voyage outward from the neighborhood of the sun. By this time the comet had faded sadly, as Professor Barnard expressed it, and, though a noticeable object, was only the ghost of its former self.
[Illustration:
HALLEY’S COMET
From photograph taken by Professor E. E. Barnard, June 6, 1910, at the Yerkes Observatory, Williams Bay, Wisconsin ]
Where is it now in its outward journey, at the present time of writing (1925)? Science can answer the question as definitely as though it were actually possessed of magic glasses, enabling it to follow the path of the retreating comet, although it has long since passed beyond our range of view. It is now approaching the orbit of the planet Neptune, crossing it in 1933, and reaches its greatest distance outward from the sun in 1943, or 3,200 million miles. In 1964 it draws near to Neptune again, and will be halfway between Neptune and Uranus in 1974, arriving at the orbit of Saturn in 1984. Once more it will gladden the eyes of mortals as it approaches the planet Jupiter, and draws near to pay its respects to its mighty ruler, the sun.
At its return in 1758 the prediction erred on the side of thirty-two days; at the return in 1835, by a margin of only two days; and in 1910, by the amount of two and one-half days. Perchance, ere it makes its next appearance in 1985,[10] the presence of another planet beyond Neptune may have been detected, explaining the disturbing factor resulting in that small discrepancy. The astronomers at that remote date (1984) may succeed, therefore, in making a prediction so exact that the comet may “swim into their ken” promptly to scheduled time. Few, if any, of the present-time readers of this book (unless it falls into the hands of a very youthful enthusiast) will be here to welcome the comet at its next return, and even the youthful enthusiast may have the distressing experience of the American astronomer Dr. Lewis Swift, who saw Halley’s comet in 1835, and was able to welcome it at its return in 1910, but, owing to failing eyesight, was unable to see it, much to his regret.
[Illustration:
The orbit of Halley’s Comet, which it passes over in 75 to 77 years, showing where the comet is to be found now, and during its course until its next return in 1985. ]
With regard to my first visit to the Yerkes Observatory, the following facts regarding the great refractor may be of interest, as well as the incident narrated to me by Miss Calvert while we were awaiting Professor Barnard’s invitation to look for Halley’s comet, on that momentous occasion. The story was deferred, in my account, to the final part of this chapter, so as not to break the thread of the actual account of my first view of the comet. Following the description of the telescope, the story of a catastrophe which nearly ended its career is best told in Professor Barnard’s own words, as quoted from the after-dinner speech, in January, 1907, at Nashville, already referred to in this book.
“The tube of this instrument is about sixty-four feet long. In the farther end of this tube is placed the great object glass, forty inches clear in aperture. When one is looking overhead with this giant telescope, he must be at a point some thirty feet or more lower than when the tube is pointed toward the horizon. To avoid the use of a high ladder to reach the observing end of the telescope in its various positions, the floor of the dome itself is made into a giant elevator, sixty-five feet in diameter. The rising and lowering of this floor—which is done by electric motors—always keeps the observer in a convenient and safe position with reference to the eye-end. This floor is suspended by heavy steel cables which go over wheels at the tops of four towers attached to the inside walls of the dome. The floor is counterpoised by heavy iron weights at the other ends of the cables.
“Within a little over a week after the completion of the instrument and when we had seen through it only once or twice, the two south cables pulled out of their sockets and the floor fell through fifty feet to the ground and was destroyed. It was a terrible wreck. This was on the morning of May 29, 1897, at 6.30 o’clock. Mr. Ellerman and I had been working all night observing with the telescope. When we quit at daylight we left the floor at its highest point for the convenience of some workmen who were to be at work on the tube in the morning. When the floor fell there was not a soul in the building, and no one was injured. A couple of hours either way, and death in all probability would have come to one or the other of us. Only a few nights before this accident the president of the University of Chicago and thirty or more trustees and prominent men of the university had seen through the telescope, and the floor had been up and down with them on it. If it had fallen then a heavy loss of life would have been almost certain. A few days before that, Mr. Clark, who made the great glass, had unpacked the forty-inch disks on the floor at its highest point, and had put them in the cell which he finally bolted to the end of the telescope. If the floor had fallen then, the great lens would have been destroyed, with the probability that no one would be able to make another, for Mr. Clark died within a few days after he returned to Cambridge. It was providential, then, that the floor fell when it did; for the fault in the attachment of the cables made it certain that it must soon have fallen.
“But this is not the end of the story. When the floor fell, it lurched against the great iron pier of the telescope and must have given it a violent blow. There was some fear that the great glass might have been injured by the shock. It was nearly a hundred feet up in the air and could not be reached to see if it was unharmed. By climbing up on the dome (which is one hundred and ten feet high) and looking down at the glass, it was seen to be apparently uninjured. Still, the test could only be made by examining the stars through it, which was not possible until the floor was replaced by a new one. Four months were occupied in taking out the wreck and putting in the new floor.
“There was great anxiety to see the sky through the glass, and the first night available it was turned to the stars. To our consternation, there was a great, long flare of light running through every bright star we examined. This was so strong and conspicuous that it would make the instrument utterly useless. It looked as if the lens had been injured by the shock of the floor against the pier. We examined it in all positions of the instrument, but we could not get rid of the glaring defect. As I had used the glass more than anyone else before the accident, my statement that the defect did not then exist made the matter all the more serious. It was with heavy hearts that we waited for day to again critically examine the lens. The next day we all examined the great glass very carefully, but could see nothing wrong with it. Then Professor Hale noticed that just back of the glass in the tube was a thick mass of spider webs stretched across the tube, all running in the same direction. Upon comparing notes we found that the direction of the spider webs coincided with that of the flare of light seen the night before. It seemed that a spider had evidently got in the tube before the object glass was put on by Clark, and had been unable to get out; for there was no opening in the tube. During the time the tube remained at rest, while the new floor was being put in, he had climbed up to the great glass in the direction of the light; and when he found his egress barred by the great window, he spun his web, perhaps as a signal of distress, or maybe in the hope that some unlucky fly might get in through the glass that he could not get out of—anyway, with the result that he caused several astronomers the most uneasy time of their lives. When these webs were swept out by one of the astronomers climbing up in the tube with a feather duster, it was found that night, when the stars were examined, that the flare had vanished and the mighty glass was uninjured.”