CHAPTER FIVE

PHOTOGRAPHY AS APPLIED TO COMETS

“With its three eyes—the eye of keenness, the eye of patient watchfulness, and the eye of artistic truth, photography promises to be a Cerberus to the science of the future, whose watchfulness will prevent the admission of error and detect truths which would otherwise escape us.”

—R. A. PROCTOR.

These words written by my father, in his book entitled _The Universe of Suns_, shortly after the appearance of the comet of 1882, have since been amply confirmed, not only in connection with the sun, moon, and stars, but still more so regarding the hitherto unknown peculiarities of comets. So far we have gained some idea of the appearance of a comet as seen with the naked eye, or with the aid of a telescope, but it now remains to be shown what can be accomplished by means of photography.

Pictures of the ever-varying transformations, for instance, which took place in the appearance of the celebrated Morehouse comet of 1908, opened out new vistas in cometary wonders, hitherto beyond our ken. Successive photographs taken during the course of a night, pictured for us the unfolding of the comet’s train, its spreading outward like a gigantic fan of gauze-like texture, and eventual closing up till it resembled a sheaf. By means of the revelations thus made by the camera, we became aware of the marvelous quick-change effects produced in the appearance of this comet not only from night to night, but sometimes during the brief interval of less than an hour. Nevertheless, as seen with a telescope, the Morehouse comet appeared inconspicuous and was invisible to the naked eye.

The first attempt at taking a photograph of a comet was made by Bond at Harvard College Observatory in 1858, in connection with the magnificent comet of that year, but his efforts only met with partial success. The next venture was made in 1881, by Sir William Huggins, in our country, and Dr. Henry Draper, of New York, but entirely satisfactory photographs of a comet were not obtained until 1882, when the great Daylight comet became a conspicuous object in southern skies.

This comet was first seen on September 3, by some employees of the railroad in Auckland, New Zealand, and by other persons whose duties required them to rise before daylight. The names of these fortunate observers are unknown, but what a privilege to obtain the first glimpse of the comet.

[Illustration:

PHOTOGRAPH OF MOREHOUSE COMET, 1908 C

Taken on November 19, 6 h. 4 m., at the Royal Observatory, Greenwich ]

Anyone acquainted with the clear, limpid blue of the skies at dawn in New Zealand, and the brilliancy of the stars despite the near approach of sunrise, may gain some idea of the vivid appearance of the little comet in their midst as seen on this occasion. The writer, who spent a year in New Zealand (1913–14), has vivid recollections of the beauty of the dawn ushering in daylight during the course of her travels to and fro, and has almost an envious feeling with regard to those fortunate people “whose duties required them to rise before daylight,” thus enabling them to obtain the first view of the comet. As in the case of the brilliant star in the East, which guided the three wise men of old to Bethlehem, doubtless they likewise “rejoiced and were exceeding glad.”

The news of the discovery of a comet was soon made known, for on September 6 Dr. Gould, director of the Cordoba Observatory in South America,[7] received information that a bright comet was visible in the east before sunrise. His informant had seen it on the morning of September 5, when it was described as being as bright as the planet Venus. At Reus, near Tarragona, it was bright enough to be seen at one time through a passing cloud when at a distance of only three times the diameter of the sun from its edge, or “limb,” as it is technically termed. According to the report of Dr. Gould regarding the weather conditions prevailing at Cordoba, the morning of September 7 was cloudy and the eastern sky overcast on every morning during a whole week. Nevertheless, on one occasion it was thought that a part of the comet’s tail could be seen. It was not until September 14 that conditions were again favorable for observing the comet.

Fortunately the link in the chain of observations was supplied by an enthusiastic amateur astronomer, Mr. John Tebbutt, who watched the comet from his observatory at Windsor, New South Wales. On September 8, he received a telegram from the Government Astronomer at Melbourne, to the effect that a large comet was reported due east at four o’clock in the morning. Other messages were received during the day from different parts of the colony, and from the information thus supplied Mr. Tebbutt was enabled to observe the comet on the mornings of September 9 and 10. By this time the nucleus of the comet was large and remarkably brilliant, and the tail about 3° or 4° in length, not quite the distance separating the pointers in Ursa Major.

[Illustration:

JOHN TEBBUTT, NOTED COMET-HUNTER OF WINDSOR, N. S. W. ]

Mr. Tebbutt had already distinguished himself as a successful comet-hunter, and in addition had vainly endeavored to form a society such as existed for comet-hunting in the northern hemisphere, but his efforts only ended in disappointment. As he wrote in his _Memoirs_, “although several astronomers owned telescopes suitable for the work, there was obviously a distaste for systematic observation.” He took great pride in his miniature observatory at Windsor, actually his own handiwork, for he was his own bricklayer, carpenter, and slater combined. During a visit to the observatory in 1912 the writer was shown numberless books containing the records of fifty-five observations of the comet of 1882, extending from September 8 of that year to March 2, 1883. These observations were made by Mr. Tebbutt with his four and a half inch equatorial, with the exception of four made with the transit instrument in full sunlight. Moreover, Mr. Tebbutt was the first to see the comet in full daylight with the unaided eye.

The second series of observations of the comet in full daylight were made at the Government Observatory, Melbourne, but it was not seen in Europe, owing to cloudy weather, until September 17, one Sunday morning. It happened that Dr. A. A. Common, the well-known amateur astronomer at Ealing, had directed his telescope to the sun for the purpose of observing sun-spots, when he had a glimpse of the comet. This was at a quarter to eleven, at which time the comet was rapidly approaching the sun. Unfortunately, clouds intervened, rendering further observations for the time being impossible.

Dr. Common sent a telegram to Dunecht (Lord Crawford’s observatory near Aberdeen) so that the astronomers there might be on the lookout for the comet, with the result that it was observed by them on the following day. In England bad weather, as usual, had baffled all attempts at seeing the comet, and the clouds seemed to be in league with the powers of darkness in keeping it hidden from view. Those who can recall watching in vain in England, for Halley’s comet at its return in 1910, can fully sympathize with the disappointed watchers of the sky in 1882. (In those days the writer was not nearly so enthusiastic as she should have been at the brief view of the comet obtained early one chilly morning. Admiration was slightly tinged with wonder at all the excitement over “a small white star with a train a yard long” which scarcely seemed worth the trouble of getting up for during the wee sma’ hours. Nevertheless, there is comfort now in the thought, that this—her first comet—was one long afterward to be remembered.)

Day after day the comet grew in splendor, until by September 12 it was almost the cause of a momentary panic on the occasion of the attack at Tel-el-Kebir. The story is told by Colonel E. Major, somewhat as follows, in his book entitled _Lord Wolseley_: It seems that each morning Sir Garnet in the early dawn had reconnoitered the enemy’s position from the high ground above their lines, and he had noticed that their pickets only came out beyond the defenses at daybreak. He therefore decided upon a night attack, which must be sudden and decisive, so that the enemy might be crushed and scattered early in the day. This would enable the cavalry to make an immediate dash for Cairo, while the infantry occupied Zagazig. After making all arrangements, we are told:

“The troops set off in silence, no smoking or giving of orders aloud being permitted. The engineers had set up directing posts as guides in the earlier part of the march, but in the deep darkness of a moonless night these were not easy to find. Only the North Star and the Little Bear, shining through the drifting clouds, gave the leaders some fixed point by which to find the way. Sir Garnet sent his own naval aide-de-camp, Lieutenant Rawson, R. N., who was accustomed to steer by the stars, to act as a guide with Sir Edward Hamley’s division. Even with this help the flanks of the Highland Brigade in the course of the night march lost their direction after a short halt, and circled round until a crescent-like formation was the result.

“A second halt was necessary to remedy the confusion. Soon after, a strange light appeared upon the horizon, and Sir Garnet feared it was the first sign of the coming dawn. If so, the night attack had failed. But no rising sun followed that long streak of light, and later on they learned that a comet had been observed in the heavens for the first time on that eve of Tel-el-Kebir.”

On September 27, the comet was seen at Vienna, according to a telegram received by the Astronomer Royal at Greenwich, but meanwhile it had been observed continuously at the Cape of Good Hope Observatory since September 8. It was seen on this date by Mr. Finlay, a member of the observatory staff, while he was going homeward after working all night at the dome. Happening to glance eastward, his attention was at once attracted by the comet. Returning hastily to the observatory, he proceeded to make the necessary measurements for recording its position with regard to a small star in its neighborhood. One can imagine the anxiety with which its reappearance was awaited next morning by Sir David Gill, the director of the observatory, and by those who may have heard the good news of a comet in the offing.

The following morning the comet was again observed, and Sir David Gill sent a telegram to Sir James Anderson, chairman of the Eastern Telegraph Company:

Kindly tell Astronomer Royal, Greenwich, that bright comet was observed here yesterday morning by Finlay. Right ascension this morning, nine hours, forty minutes, increasing hourly, nine minutes. Declination one degree south, increasing half degree south daily.

Unfortunately, the telegram failed to reach its destination, and was doubtless delayed or mislaid in the confusion of numberless war messages. The first news that reached Europe about the comet was obtained by means of a telegram on September 12, from Dr. Cruls, director of the observatory of the Emperor of Brazil. Sir David Gill was anxious to prove Mr. Finlay’s claim to priority in discovering the comet, but, as we have already seen, he had been forestalled by astronomers in Australia, and some claim should be allowed for the “early railroad workers” in Auckland, New Zealand, who were actually the first to see the comet, though their observation thereof had no practical value. For a while the comet was known as the Cruls comet, but now it is generally referred to as the great comet of 1882, or the Daylight comet. However, later on, as we have already noted, it had a rival as a Daylight comet in 1910, when a fine comet resembling the plume-like appearance of the comet of Donati was seen to advantage in England.

The great comet had another rival in popularity in the year 1882, for on May 17, when Dr. Schuster was developing photographic plates taken during a total eclipse of the sun which occurred on that date, he found a miniature comet seemingly entangled in the outer rays of the corona. This is the sun’s crown of glory which can be seen only during the time the glare of sunlight is hidden from view by the moon coming directly between the sun and the earth. The consequent darkness, or totality, as it is called, can never exceed a duration of eight minutes, and on this occasion during a still briefer interval of time the little comet was captured by means of the camera. Thus, a permanent record was secured of its presence near the sun, but as it had not been seen before nor was it seen afterward, its motion must have been extremely rapid, and it may possibly have been drawn inward and consumed by the intense solar heat. Despite its small size and brief career, it is distinguished by the name of Tewfik, after the then Khedive of Egypt. It has been suggested that the comet may be kin to, or one and the same with, a comet which had its photograph taken during the total eclipse of the sun, April 16, 1893, having a period like that of the sun-spots, of about eleven years.

Possibly Sir David Gill may have had the photograph of Comet Tewfik in mind when he heard of attempts which had been made by Mr. Shoyer of Cape Town, and Mr. Simpson of Aberdeen, to photograph the comet of 1882. The results had been so far successful as to prove that the comet was capable of giving a distinct impression after sufficiently long exposure. But it was owing to the cordial and enthusiastic assistance of Mr. Allis, photographer of Mowbray, that the first pictures of the comet were obtained. When Mr. Allis, under the direction of Sir David Gill, fastened a simple portrait camera upon the tube of one of the Cape telescopes, and pointed it at the great comet, little did he dream that the experiment would eventually lead to such great results in the future. One can imagine the thrill of triumph as the experimenter watched the gradual process of development on the photographic plate, until, as if by magic, a fine comet was revealed outlined against a starry background. Thus, three or four photographs were obtained, which excited the greatest interest among astronomers in the northern hemisphere. Possibilities were suggested with regard to the construction of a self-recording photographic star chart, thus replacing the painstaking hand-drawn star charts of the Herschels, Argelander, my father, and other astronomers at various times engaged in such work.

The gigantic undertaking was ultimately divided among nineteen observatories situated in northern and southern climes, which will eventually result in a marvelous collection of star charts. These will include millions of stars, forming a celestial library which may be consulted at leisure either now or a century hence when the makers thereof may have become a mere memory. If a supplementary set is made in the future, comparisons between the two series may result in important information with regard to star drift. (It was by comparing star charts thus made a century apart, that my father originated the star-drift theory, by his observations in connection with the five stars of Ursa Major in 1868, a theory confirmed by the spectroscopic investigations of Dr. Huggins.) Celestial photography, owing to Dr. Gill’s suggestion with regard to the star-gemmed photographs of the comet of 1882, may add greatly to our knowledge in connection with such problems, the records of the past thus becoming the star-lettered volumes for the students of the future. Undoubtedly this achievement, the result of the photographs taken of the great comet of 1882, ranks high among those which make astronomy appeal so vividly to the imagination.

Now let us see how Mr. Allis went to work in obtaining the portrait of this memorable comet. To secure a perfect picture of its delicate detail, an exposure of not less than half an hour was required. To obviate the difficulty caused by the rotation of the earth, Mr. Allis attached his camera with a rapid portrait lens and sensitive dry plate to the declination axis of a large equatorial, and then turned both the telescope of the equatorial and the camera in the direction of the comet. Matters were so arranged that in whatever direction the telescope was turned, the small camera would turn exactly with it, and thus by means of clockwork and proper small motions for delicate adjustment, the comet was kept accurately in the field of view during the whole time of exposure. The camera was therefore also pointed during the whole exposure to precisely the same point of the comet, and in this way, after one preliminary failure, three very beautiful and quite invaluable negatives of the comet were obtained. These three negatives will remain of permanent value as a scientific record of one of the most glorious comets ever seen.

To follow the progress of the comet as it increased in splendor day by day, let us return to the record of Dr. Gould, director of the Cordoba Observatory. On September 16, we are told that the brightness of the comet was such that it was visible with the finding telescope throughout the day. The next day it was so bright that it could be easily observed in full sunlight, and at eleven o’clock that morning the sun and the comet were in the same field of view. Then the comet was hidden for a while, as it passed between us and the disk of the sun.

[Illustration:

THE GREAT DAYLIGHT COMET, SEPTEMBER, 1882

Photograph taken at the Royal Observatory, Cape of Good Hope ]

On Monday, September 18, the brilliancy of the comet attracted popular attention throughout the country, and the “blazing star” near the sun was the one topic of conversation. In the small telescope it presented the aspect of a brilliant nebulous mass, having on each side curved appendages like horns or wings, nearly as large as the central body, and at their base quite as brilliant, the general form of the whole reminding one of the winged globes carved on ancient monuments. This appearance, doubtless due to the outbreak of glowing vapors from the nucleus, was also exhibited, although to less extent, on the following two days, during both of which the comet remained visible to the naked eye.

Observations made of the comet with large telescopes showed that the nucleus had separated into six or eight star-like knots strung like pearls along a luminous streak some fifty thousand miles in length. The largest of these knots was some five thousand miles in diameter, an interesting fact as compared with the size of the earth, which is 7,925 miles, according to the British Astronomical Association Handbook for 1925.

A faint straight-edged beam of light, or “sheath,” accompanied the comet, enveloping the head and projecting like a hood three or four degrees in front. Besides this, three or four irregular shreds of cometary matter were detected, escorting the comet, as it were, like airplanes, at a distance of three or four degrees when first seen, but gradually receding from it, and at the same time growing fainter. The actual length of the comet’s train at one time exceeded one hundred million miles, more than the distance of the sun from the earth. (If the head of the comet had rested on the earth, and its train stretched outward toward the sun, it would have extended seven million miles beyond that luminary.)

The trains of comets have been grouped under three types, _viz._, the long straight rays as shown in the photograph of Halley’s comet, though this was only one of the many outlines assumed; the second is the curved, plume-like train resembling that of the comet of Donati; and thirdly the short stubby brushes violently curved. The great Daylight comet had a greatly curved train belonging to the second type, and it was mainly composed of carbon compounds. The curvature of the train was due to matter for which the repulsive force is only a fraction of the gravitational force. The pressure of light from the sun was a most important factor in the formation of its train.

When the fierce pressure of the sun’s light strikes upon the particles forming the train, it drives the particles which are of the same relative size as the particles of light along with them, just as when the waves of the sea break against a beach they tend to drive small pebbles and sand upward along the beach.

HINTS FOR AMATEUR PHOTOGRAPHERS

To an amateur photographer who desires to obtain the picture of a comet which may appear perchance in the near future, their capricious appearance at unexpected periods being one of their charms, the following hints may be most acceptable. For work of this kind an equatorial telescope is used with a photographic lens and camera strapped thereon. The telescope is mounted on an axis that is parallel to the earth’s axis, and is made to rotate westward by what is called a driving-clock just as fast as the earth turns to the east. It will follow the motion of the sky (which apparently drifts westward), and keep every star approximately fixed in the field of view, or on the photographic plate in the attached camera.

Otherwise, the stars will appear as trails of light, caused by the rotation of the earth as it moves onward at the rate of nineteen miles a second, which is rather disturbing to an astronomer who may be desirous of obtaining a photograph of the stars overhead. What is he to do? Here is our planet turning eastward and the stars apparently drifting westward, and unless the telescope is made to keep up with the stars by means of clockwork the results are disastrous. Consequently, the telescope is made to follow the star, comet, or whatever the desired celestial trophy may be, and it is kept in such a position that the object in view is centrally placed at the intersection of two threads obtained from a spider’s web. For this reason, spiders are treated with due respect in observatories, and may explain the expression of dismay the writer saw on the face of an Indian assistant at the Kodaikanal observatory in southern India, when she nearly dispatched one of these noxious insects, which succeeded, however, in deftly eluding destruction.

[Illustration:

PHOTOGRAPH OF A BRIGHT METEOR BY DR. W. J. S. LOCKYER ]

The star trails shown in the photograph taken by Dr. W. J. S. Lockyer give an excellent idea of what happens to a photograph of the stars when the clockwork is allowed to run down. In this instance the telescope, with the accompanying camera, was stationary during the exposure of a little over two hours, with the result that the stars photographed are not points of light, but bright and faint lines in sections of circles, since the telescope was pointed to the pole of the heavens. The interest in this photograph is increased by the fact that a meteor dashed across that part of the sky during the course of the exposure, thus resulting in one of the finest photographs of a meteor ever obtained.[8] Had the exposure lasted during twenty-four hours, and the photograph been taken in Norway some time during the course of their long winter night, the trails would have been complete circles. By this means we do not get a picture of the stars, but simply a photograph illustrating the rotation of the earth. To obtain a picture of the stars, therefore, an equatorial attachment, as above described, is an absolute necessity.

Some people have an idea that all an astronomer has to do in making photographs of a comet, or other celestial object, is to turn the telescope in the direction wanted, strap on the camera, wind up the clock, and then go homeward for a good night’s rest. Unfortunately, no driving-clock has yet been devised so perfect as to move the telescope exactly with the stars. According to Professor E. E. Barnard, who was an expert on such matters—

“There is always more or less irregularity of motion, all of which would be recorded on the plate, and the stars, instead of showing as merely points of light, would be elongated and blurred. The fainter ones would not show at all, because they could not be still long enough to have their pictures taken. That is why you see in the photograph the observer with his eye ‘glued to the telescope,’ watching a star, a guiding star which he constantly keeps behind the intersection of two illuminated spider threads in the eyepiece, by the slow-motion rods which are controlled by his hands.”

Thus, every star or comet is kept immovable on the sensitive plate, and it paints its own portrait as long as the telescope is made to turn westward as fast as the earth rotates eastward. That is why a driving clock is absolutely necessary for the amateur comet photographer who is desirous of obtaining accurate results. Many hours are required in obtaining a successful photograph of such comets as the Morehouse comet, the sensitive plate requiring sometimes an exposure of many hours before it reveals satisfactory results. The observer must sit patiently hour after hour, guiding the instrument, and the writer has some idea of what this must mean, from a brief five minutes’ experience at Mount Wilson in connection with the sixty-inch reflector. As a great favor she was allowed to hold the bulb in her hand which by the slightest pressure brought back an erring star which had attempted to stray momentarily from the center of the field of view of the telescope.

When one considers the hours spent by the late Professor Barnard in this nerve-racking work, the patient endurance of the astronomers who specialize in celestial photography becomes evident. It is an arduous task, and one doubtless subject to many disappointments, to avoid which Professor Barnard tried to formulate some set of rules that would be dependent on the local time and position of the comet, but these were finally rejected.

“So much would depend on the purity of the atmosphere at the time, the size and light ratio of the lens, the kind of plate used, etc., that they would probably lead to the very errors against which we wish to guide.”

The position of the comet with respect to the point of sunrise or sunset, and freedom from any form of haze in the sky, are important factors in the exposure of comet plates. Moreover, it is necessary that they should not be exposed too early in the evening or too late in the morning, in either case resulting in unsatisfactory negatives. The best of all rules is the judgment of the observer at the moment, but only long experience will warn one by a glance at the sky when there is danger of failure in this class of work. It is the few moments at the beginning or end of the exposure that will injure or ruin the plate.

With a small portrait lens (the most useful size is about six inches) essentially everything about a comet will be shown as quickly as with a larger one. The main advantage of the large lens would lie in its greater scale—which of itself is of great importance. Another source of danger is moonlight, especially in the case of a long exposure. Nevertheless, according to Professor Barnard, important results may be obtained in full moonlight, if the comet is not too near the moon. Much, however, will depend upon the clearness of the atmosphere; the purer it is the less will the moonlight affect the plate. In this case a dew-cap helps much. On an ordinary moonlit sky an exposure of half an hour with a quick portrait lens will not ruin a fast plate if the comet is not too near the moon. In full moonlight, however, a longer exposure, unless under exceptional conditions, will seriously injure or ruin the plate. With the half-hour exposure the plate will be fogged, and of course the best quality of negatives cannot be obtained therefrom. All plates should be backed to prevent halation. A backing made of sugar and burnt sienna is recommended as entirely satisfactory, and can be kept in stock.

The formula as supplied by the Cramer Dry Plate Company is as follows: Cook two pounds of granulated sugar in a saucepan, without the addition of any water, until it is nearly in the caramel or fudge stage. Then stir in one pound of burnt sienna and cook a little longer, stirring well. Do not let the backing get sticky, or it will be difficult to handle and will not soften so readily when removed from the plate. Finally add about half an ounce of alcohol to each pint as a drier. Put away in a wide-mouthed stoppered bottle or jar. When needed for use, dilute a little of this with water to the consistency of a thick but not too wet paste. Apply (not wet enough to run) to the back of the plate with a wide camel’s hair brush. It is not necessary to back heavily. A sheet of soft paper (an old newspaper) pressed on the backed surface will prevent injury to the plate, which should be freshly backed when ready for use. If kept in stock a long time after being backed, an unequal fogging is likely to occur.

Before developing, remove the backing while it is still damp, with a moist piece of absorbent cotton. Should a small amount remain it will not affect the developer seriously. The plates should be carefully dusted with a broad soft camel’s hair brush, after being put in the plate-holder. The camera tube should be wiped out frequently with a damp cloth to free it from dust. It should also have a tight-fitting cover at the plate end to keep it closed when the plate-holder is not in position. There should be four springs, one at each corner, on the back of the plate-holders, to press the plate forward in a constant position.

On account of its greater sensitiveness the Lumière Sigma plate is recommended by Professor Barnard, although he draws attention to the fact that this plate has frequently been found defective in having small, round, transparent and opaque spots. It is also more subject to “chemical fog” than the Cramer or Seed. Otherwise, it is a beautiful and very rapid plate.

When the comet is at its brightest, the Seed 27 Gilt Edge plates are recommended on account of their general freedom from defects and finer grain. With these few suggestions in respect to photographing comets, made by Professor Barnard in _Popular Astronomy_, No. 170, the amateur comet-hunter is enabled to make an attempt, at any rate, at photographing those wonders of the heavens which have proved so attractive on account of their varying appearance from night to night. For those who may not have a ready access to astronomical libraries, the above condensed account from Professor Barnard’s article on the subject should prove invaluable.

In an account of his life-work given by Professor Barnard during the course of an after-dinner speech in January, 1907, at Nashville, and entitled by him, “Some Unastronomical Experiences of a Lecturer,” he referred to his interest in comets as follows:

“I have always been interested in comets. These remarkable objects, which sometimes sweep across the heavens with their wonderful trains of light, and which in all ages have been objects of superstition and terror, are among the most interesting in the heavens. Little by little the mystery attached to them is being solved. This has been done mainly through the aid of photography. Many of the physical phenomena of the tails of comets are too faint to be seen with the eye, although it may be aided by a powerful telescope; but the photographic plate secures a permanent record of these in all their complexity and beauty. These photographs show that the form and other peculiarities of a comet’s tail are often utterly transformed from night to night. It is therefore highly important that a continuous series of photographs should be obtained of every active comet that can be observed, for their phenomena are as evanescent as smoke itself.

“In 1892, at the Lick Observatory, I was engaged in photographing a comet (Swift’s) then visible in the morning sky just before daylight. Every morning’s picture increased the interest and importance of the work. Unfortunately, I had arranged for a lecture in the Normal School at San José for the night of May 6. I did not want to disappoint the people, and I certainly could not let the comet go by unphotographed. San José was nearly a mile below us in vertical height and twenty-seven miles distant by stage road. The only possible way for me to secure my photograph and not disappoint my audience was to return to Mt. Hamilton that night after the lecture. At ten o’clock I hired a horse and buggy in San José and drove up that lonely mountain road, the journey taking five hours, and arrived at the summit at three o’clock in the morning, in time to make a photograph of the comet.

[Illustration:

COMET 1893 IV BROOKS

Exposures of October 21, 22, and 23, showing probable encounter with some medium which shattered the tail. Taken at Lick Observatory by Professor E. E. Barnard ]

“The picture that I got proved to be a very important one, as the comet was then undergoing the most remarkable changes. I must say that a good many thrills passed over me during that lonely mountain ride in the dead of night—some for the chance that I might drive over into a cañon to death, and others for the possible interruption of my terrestrial existence through an encounter with some hungry, roaming mountain lion. In the main, the journey was a most impressive one. Alone in the mountains, with only the horse in front and my friends the stars above me, I doubt if my courage had not failed me entirely if the friendly stars had not encouraged me with their presence.”