If stars of magnitude 10 are observed correctly,
then""9"0.10 secs. too early
""8"0.16"
""7"0.19"
""6"0.21"
""5"0.23"

This may serve as an illustration of various incidental results which are already flowing from the enormous and laborious piece of work which, as far as the University Observatory at Oxford is concerned, we have just completed, though some of the other colleagues are not so far advanced. Main object of the work.But the main results will not appear just yet. The work must be repeated, and the positions of the stars just obtained must be compared with those which they will be found to occupy at some future date, in order to see what kind of changes are going on in the heavens. Whether this future date shall be one hundred years hence, or fifty, or ten, or whether we should begin immediately to repeat what has been done, is a matter not yet decided, and one which requires some little consideration.

I have said perhaps enough to give you a general idea of the work on which we have been engaged at Oxford for the last ten years. Ten years ago it seemed to stretch out in front of us rather hopelessly; the pace we were able to make seemed so slow in view of the distance to be covered. We felt rather like the schoolboy who has just returned to school and sees the next holidays as a very remote prospect, and we solaced ourselves much in the same way as he does, by making a diagram representing the total number of plates to be dealt with and crossing off each one as it was finished, just as he sometimes crosses off the days still remaining between him and the prospective holidays. It was pleasant to watch the growth of the number of crosses on this diagram, and by the end of the year 1902 we had the satisfaction of seeing very little blank space remaining.The concluding year. Now, up to this point it had not much mattered whether any particular plate was secured in any particular year, or in a subsequent year, so long as there were always sufficient plates to keep us occupied in measuring them. But it then became a matter of importance to secure each plate at the proper time of year; for the sun, as we know, travels round the Zodiac among the stars, obliterating by his radiance a large section of the sky for a period of some months, and in this way a particular region of the heavens is apt to “run into daylight,” as the observatory phrase goes, and ceases to be available for photography during several months, until the sun is again far enough away to allow of the particular region being seen at night.

Roughly speaking then, if a plate which should be taken in February is not secured in this month owing to bad weather, the proper time for taking it will not occur again until the following February; and when there was a fair prospect of finishing our work in 1903, it became important to secure each plate at the proper time in that year. Hence we were making special efforts to utilise to the full any fine night that Providence sent in our way, and on such occasions it is clearly an economy, if not exactly to “make hay while the sun shines,” at any rate to take plates vigorously while the sun is not shining and the night is fine; leaving the development of them until the daytime. There is, of course, the risk that the whole night’s work may in this way be lost owing to some fault in the plates, which might have been detected if some of them were immediately developed. Perhaps in the early days of our work it would have been reckless or foolish to neglect this little precaution; but we had for years been accustomed to rely upon the excellence of the plates without finding our trust betrayed; and the sensitiveness of the plates had increased rather than diminished as time went on.A disappointment. Hence it will be readily understood that when one fatal morning we developed a series of some thirty plates, and found that owing to some unexplained lack of sensitiveness they were all unsuitable for our purpose, it came as a most unwelcome and startling surprise. It was, of course, necessary to make certain that there was no oversight, that the developer was not at fault, and that the weather had not been treacherous. All such possibilities were carefully considered before communication with the makers of the plates, but it ultimately became clear that there had been some unfortunate failure in sensitiveness, and that it would be necessary to repeat the work with opportunities restricted by the intervening lapse of time. However, disappointments from this or similar causes are not unknown in astronomical work; and we set about this repetition with as little loss of time and cheerfulness as was possible. Under the circumstances, however, it seemed desirable to examine carefully whether anything could be saved from the wreck—whether any of the plates could be admitted as just coming up to the minimum requirements. And I devoted a morning to this inquiry.A curious plate. In the course of it I came across one plate which certainly seemed worth an inclusion among our series from the point of view of the number of stars shown upon it. It seemed quite rich in stars, perhaps even a little richer than might have been expected. On inquiry I was told that this was not one of the originally condemned plates, but one which had been taken since the failure in sensitiveness of the plates had been detected; was from a new and specially sensitive batch with which the courteous makers had supplied us; but though there were certainly a sufficient number of stars upon the plate, owing to some unexplained cause the telescope had been erroneously pointed, and the region taken did not correspond to the region required. To investigate the cause of the discrepancy I thereupon took down from our store of plates the other one of the same region which had been rejected for insufficiency of stars,A strange object. and on comparing the two it was at once evident that there was a strange object on the plate taken later of the two, a bright star or other heavenly body, which was not on the former plate. I have explained that by repeating the exposure more than once, it is easily possible to recognise whether a mark upon the plate is really a celestial body or is an accidental blot or dust speck, and there was no doubt that this was the image of some strange celestial body. It might, of course, be a new planet, or even an old one which had wandered into the region; but a few measures soon showed that it was not in movement. The measures consisted in comparing the separation of the three exposures with the separation of the corresponding exposures of obvious stars, for the exposures were not, of course, simultaneous, and if the body were a planet and had moved in the interval between them, this would be made manifest on measuring the separations. No such movements could be detected; and the possibilities were thus restricted to two. So far as we knew the object was a star, but might be either a star of the class known as variable or of that known as new. In the former case it would become bright and faint at more or less regular intervals, and might possibly have been already catalogued; for the number of these bodies already known amounts to some hundreds. Search being made in the catalogues, no entry of it was found, though it still might be one of this class which had hitherto escaped detection.A new star? Or it might be a “new star,” one of those curious bodies which blaze up quite suddenly to brightness and then die away gradually until they become practically invisible. The most famous perhaps of these is the star which appeared in 1572, and was so carefully observed by Tycho Brahé; but such apparitions are rare, and altogether we have not records as yet of a score altogether; so that in this latter case the discovery would be of much greater interest than in the former. In either event it was desirable to inform other observers as soon as possible of the existence of a strange body; already some time had elapsed since the plate had been taken, March 16th, for the examination of which I have spoken was not made until March 24th. Accordingly, a telegram was at once despatched to the Central Office at Kiel, which undertakes to distribute such information all over the world, and a few post-cards were sent to observers close at hand who might be able to observe the star the same night. Certain observations with the spectroscope soon made it clear that the object was really a “new star.”

This, therefore, is the discovery which we made at Oxford: as you will see, in an entirely accidental manner, during the course of a piece of work in which it was certainly never contemplated.The discovery accidental. Its purely accidental nature is sufficiently illustrated by the fact that if the plates originally supplied by the makers had been of the proper quality, the plate which led to the discovery would never have been taken. If the plates exposed in February had been satisfactory, we should have been content, and should not have repeated the exposure on March 16th. Again I can testify personally how purely accidental it was that the examination was made on March 24th to see whether anything could be saved, as I have said, from the wreck. The idea came casually into my mind as I was walking through the room and saw the neat pile of rejected plates; and one may fairly call it an accidental impulse. This new star is not, however, the first of such objects to have been discovered “accidentally”; many of the others were found just as much by chance, though a notable exception must be made of those discovered at the Harvard Observatory, which are the result of a deliberate search for such bodies by the careful examination of photographic plates.Mrs. Fleming’s discoveries. Mrs. Fleming, who spends her life in such work, has had the good fortune to detect no less than six of these wonderful objects as the reward of her laborious scrutiny; and she is the only person who has thus found new stars by photography until this accidental discovery at Oxford. The following is a complete list of new stars discovered to date:—

List of New Stars.

Ref. No.Constellation.Year.Discoverer.
1Cassiopeia1572Tycho Brahé.
2Cygnus1600Janson.
3Ophiuchus1604Kepler.
4Vulpecula1670Anthelm.
5Ophiuchus1848Hind.
6Scorpio1860Auwers.
7Corona Borealis1866Birmingham.
8Cygnus1876Schmidt.
9Andromeda1885Hartwig.
10Perseus1887Fleming.
11Auriga1891Anderson.
12Norma1893Fleming.
13Carina1895Fleming.
14Centaurus1895Fleming.
15Sagittarius1898Fleming.
16Aquila1899Fleming.
17Perseus1901Anderson.
18Gemini1903At Oxford.

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MARCH 1, 1903 MARCH 14, 1903