3. Dreyer and his Work

J.L.E. Dreyer

On Robinson's death, the immediate need was to appoint a new Director. All the previous astronomers at Armagh - Hamilton, Davenport and Robinson - had been Irish and in Holy Orders, but their successor was neither. He was a Dane, John Louis Emil Dreyer, and he came of a long line of distinguished soldiers. His grandfather had been a staff officer in Napoleon's army, under Marshal Davout; his father had served with great distinction in the Danish-Prussian war of 1864, and had afterwards become Minister of War and Marine in the Danish Government. Yet Dreyer had strong connections with Ireland. His wife, nee Tuthill, came from Kilmore in County Limerick, and Dreyer himself had worked first at Birr Castle and then at Dunsink. He proved to be an excellent director at Armagh, and remained there for over thirty years.

He was born at Copenhagen on 13 February 1852 52 53. At the age of five he started school, and showed immediate ability not only at scientific subjects but also in history - later, of course, he became one of the foremost authorities on historical astronomy. When aged fourteen, he came across a book dealing with the great Danish astronomer Tycho Brahe, and it was this book which made him decide to be "an astronomer and nothing else". Probably Tycho was never far from his mind, and he spent many years in collecting and editing the many observations and papers that Tycho had left. Actually, Tycho, who had died as long ago as 1601, was one of the most picturesque characters in the whole history of science. He was the last and probably the ablest of the pre-telescopic observers, and his star catalogue was amazingly good in view of the fact that it was made with no optical equipment whatsoever. He built an observatory on the island of Hven, between Denmark and Sweden, and laboured there for several decades; Hven became a sort of astronomical Mecca, and among the many visitors was the man who later became King James I of England. It is true that Tycho was no theorist, and he was much too narrow-minded to believe the "heretical" view that the Earth is a planet moving round the Sun; instead, he developed a weird system of his own in which nobody else had much faith. Ironically, it was Tycho's superbly accurate observations of the movements of. the planets, particularly Mars, which led his assistant Kepler to demonstrate the truth of the heliocentric theory. It was therefore fortunate that Kepler came into possession of all Tycho's observations after the death of the great Danish astronomer in 1601.

Tycho's character was frankly curious. He was, above all, an aristocrat, and very conscious of it; in his youth he had part of his nose sliced off in a duel, and made himself a new one out of gold, silver and wax; his observatory at Hven contained unusual features, such as a prison; and his retinue included a pet dwarf. He was cordially hated by the islanders, and eventually he was forced to leave Denmark to end his days in what is now Czechoslovakia. But his skill was never in doubt, and John Louis Emil Dreyer had a tremendous and justified admiration for him.

More will be said about Dreyer's historical researches later. Meanwhile, it is worth noting that in his early days he received great encouragement from the astronomers at Copenhagen Observatory, H. d'Arrest and (particularly) Schjellerup; when he was eighteen he was even given his own key to the Observatory so that he could use the instruments there at any time. He entered the University, and gaineded his Doctorate of Philosophy. His first astronomical paper, "On the Orbit of the First Comet of 1870", was published in the Astronomische Nachrichten for 1872. It was the forerunner of many.

In 1874 he received an intriguing offer. Dr. Copeland, Lord Rosse's assistant at Birr Castle, resigned to become Astronomer Royal of Scotland, and Dreyer was invited to take his place. The chance was too good to turn down, and Dreyer left Denmark; in fact, he never again lived in his native country. He arrived at Birr, and until 1878 he used the 72-inch Rosse reflector, then the most powerful telescope in the world. In the main, he concentrated upon studies of clusters and nebulae, and some of his drawings were of the highest quality. (Of course, this was before the days of detailed astronomical photography, though the photographic era was just beginning.) During his period at Birr, Dreyer published his first major contribution to astronomical science - a supplement to Sir John Herschel's catalogue of nebulae and clusters54, which proved to be the forerunner of his own classic New General Catalogue. It must have been with inward regrets that he moved, in 1878, to succeed Burton as assistant at the Dunsink Observatory. Here he was in charge of the meridian circle, and made many observations before he made his next and, as it proved, final move to a new appointment. His ability and personal merits made him an obvious choice for the directorship at Armagh, and a few months after Robinson's death he accepted the position, though because of necessary repairs to the dwelling-house he did not actually move in until 31 August 1882.

It is an old cliche that "new brooms sweep clean". In this case there was a good deal of sweeping to do. It was not Robinson's fault in any way; he had, after all, been almost ninety when he died, and he had had to battle against tremendous difficulties, the worst of which were financial. Even though he had been a relatively well-off man, it had been impossible for him to pay for the cost of publishing the observations which had been made with the mural circle since its reconstruction in 1862. Worst of all was the inadequacy of the equipment at Armagh, of which Robinson had been so painfully aware. The only instruments of real use were the mural circle itself, and the 15in. reflector, whose mirror had been re-figured in 1871 by Grubb. Even the mural circle was out of date. In Dreyer's own words55; "It is true that in careful bands it produces star-places not much inferior to those found by more modern instruments . . . but it seems of little use to continue beyond the present series to observe with this instrument." The 15in. reflector was tolerable, but needed modification. A refractor of fair size was urgently needed for micrometrical work, since the largest then at Armagh had an aperture of only 3.75 inches. The 9in. Herschel reflector had been officially listed by Robinson as "useless".

However, Dreyer felt that the observations made with the mural circle since 1862 would be well worth publishing, and he had no intention of allowing them to go to waste. He managed to obtain an £80 grant from the fund administered by the Government Grant Committee of the Royal Society, and at last, in 1886, the Second Armagh Catalogue appeared56; Dreyer also produced a list of the proper motions of 29 stars detected while the Catalogue was being prepared57. These may be said to mark the last astronomical contributions of that great observer, Romney Robinson.

Dreyer himself was a skilled writer, and for a time he had even edited an international astronomical journal, Copernicus, which lasted from 1881 to 1884. But on his arrival at Armagh, he set himself two immediate tasks. One was to obtain a really powerful telescope The second was to draw up a reliable list of the positions of star-clusters and nebulae. He was not satisfied with the 15in. reflector, even though he used it to obtain a good observation of the 1882 transit of Venus58. Neither was he satisfied with existing catalogues of nebulous objects.

First things first - and Dreyer took the obvious course; he opened a subscription list with the object of erecting a large equatorial refractor as a memorial to Romney Robinson. This should have provided sufficient funds, but in the event it did not. Only about £85 was collected, and this certainly would not pay for a telescope of the kind that Dreyer wanted. The only solution was to make a new appeal to the Government, and this was done. Happily, it produced results. In a letter to the Archbishop of Armagh (who had signed the appeal), dated 21 December 1883, Leonard Courtnay of the Treasury wrote that under the circumstances it had been decided to grant the Observatory £2000, adding prudently that "it must be clearly understood that the Observatory must look for no further assistance from the Government". The grant was a tremendous relief. It was paid over in August 1884, and at last it became practicable to place an order for a large refractor. Dreyer was fully occupied with this and with the preparation of the Second Armagh Catalogue; he was much too busy to lead the Pacific expedition to observe the total eclipse of the Sun, as he had been invited to do.

The next step was to decide on the form of the instrument. Two eminent astronomers, R. S. (later Sir Robert) Ball and Dr. Johnstone Sooney, recommended the type known as the dialyte. Grubb, who was to make the telescope, seems to have approved of this idea, but Dreyer did not, The dialyte was, in some respects, experimental, and it was necessary to be very sure of success; after all, it would be out of the question to obtain a second telescope if the first one proved to be unsatisfactory. So Dreyer wrote that after the most careful consideration, and much as he admired the ingenuity of the dialyte, he recommended a conventional 10-inch equatorial. The Governors accepted this decision, and the order was duly placed. In retrospect it seems clear that Dreyer's decision was the right one.

Grubb 10 inch Refractor

So far as the refractor was concerned, there were no difficulties whatsoever. The optics were well up to Grubb's usual high standard, and the instrument was finally set up on 28 July 1885;4 on the same evening, Dreyer had his first look through it. To-day, it is still much as it used to be when first built - and there is, indeed, no need for any modification. A great deal of work has been done with the telescope, and there will be more in the future. The mounting is quite conventional, and perfectly rigid; the clock drive, which is weight-driven, does all that is required of it. The dome has been slightly less satisfactory, but the worst of its troubles have long since been overcome.

In point of fact, the dome was paid for out of the Robinson Memorial Fund, which had crept up to almost £100. It has an ironwork framework, and was covered with papier-mache, which did not prove to be as effective as Grubb had expected; later, Ellison, who succeeded Dreyer as Director, had some hard things to say about it. But this was a comparative detail, and Dreyer lost no time in putting the instrument to work. Regular observing with it began in September 1885, and the first programme involved re-examining some nebulae which had been suspected of change. It was found that although some nebulae apparently varied in brightness, there was no well-established case of a change in form or position, as Dreyer stressed in his paper on the subject published in 1886.59 The next step was to study a number of doubtful objects which had been recorded during the preparation of a new catalogue of nebular objects. And since this catalogue represented such an important landmark both in Dreyer's career and that of the Observatory, it must be dealt with in slightly more detail.

Some star-clusters are visible with the naked eye. The most famous of them is, of course, the Pleiades or Seven Sisters, known since antiquity; there are legends about the cluster told in almost every country. Equally conspicuous, though much looser, is the cluster known as the Hyades, round the brilliant orange star Aldebaran in Taurus. (To be accurate, Aldebaran is not a member of the cluster; it simply happens to lie more or less between the Hyades and ourselves, though this interesting point was established only when it became possible to measure proper motions, during the nineteenth century.) Another naked-eye cluster is Praesepe or the Beehive, in Cancer, while in the southern hemisphere there are two prominent globular clusters, Omega Centauri and 47 Tucanae, which are of quite different type. Of gaseous nebulae, only a few may be seen without optical aid, the best-known being that in the Sword of Orion; external galaxies are in general fainter, because of their immense distances, and there are only three within naked-eye range. One is the Great Spiral in Andromeda. The other two, the Magellanic Clouds or Nubeculae, lie in the far south, and are never visible from Ireland; nevertheless, much will be said about them later, because at present they are being intensively studied from the Boyden Observatory in Africa, with which Armagh has the closest links.

Several catalogues of clusters and nebulae had been published before Dreyer took the matter up. The first was due to a French astronomer, Charles Messier, in the latter part of the eighteenth century. Messier was a comet-hunter, and a very successful one; he had an inexhaustible store of patience, and every clear night was spent in searching for new comets and re-observing known ones. For some time he experienced trouble from faint clusters and nebulae, some of which look remarkably like comets-particularly in low-magnification telescopes of the kind used by Messier. Each time an object of this sort came into view, it was necessary to go through a checking process to make sure that it was not a nebula or anything so permanent. No reliable catalogue was available, so Messier decided to make one. He produced a list of about one hundred nebulous objects, and numbered them, giving their positions with fair accuracy. Thus the Andromeda Spiral became Messier 31, or M.31; the Orion Nebula was M.42, and so on. Messier's catalogue is still used, and the M-numbers are known to astronomers everywhere, while his 16 comets, though not forgotten, are known but to a limited group of specialists.

This was a start, but nothing more, and it was left to the great Sir William Herschel to put nebular studies on a firm footing. Using his reflectors, which were the most powerful in the world and remained so until the building of Lord Rosse's 72in. in Ireland, Herschel made detailed "surveys of the sky" (during one of which he discovered the planet Uranus, in 1781), and published numerous papers, largely in the Philosophical Transactions and a few in the Monthly Notices of the Royal Astronomical Society, giving accounts of his discoveries and observations*. His son John also became an observer of the highest skill, and it was he who, in the 1830's, took a large telescope to the Cape of Good Hope and made the first systematic survey of the southern skies - unless one includes the understandably less detailed survey made long before by Edmond Halley from St. Helena.

In 1864 Sir John Herschel published his General Catalogue of Nebulae. The observations had been made mainly by his father and himself, and the catalogue represented an important advance in this particular field of astronomy. However, it was not complete - no such claim was ever made for it, least of all by John Herschel himself - and in the years following 1864 many extra nebulous objects were discovered with the more powerful telescopes becoming available. And it was at Birr Castle, of course, that Lord Rosse's reflector

The Royal Astronomical Society was founded only at the end of Herschel's career. Herschel himself became the first President. first showed that some of the "starry nebulae" are spiral in form, like vast Catherine-wheels.

At the time when Dreyer began his work at Armagh, ideas about the universe were decidedly primitive judged by modern standards. In all catalogues, clusters, gaseous nebulae and galaxies had been lumped indiscriminately together; Messier's list even includes the Crab Nebula in Taurus (M.1), which is, of course, an exceptional object, inasmuch as it is the remnant of a supernova observed by Chinese and Japanese astronomers in the year 1.054.* And M.27, in Vulpecula (the Fox) is the Dumb-bell Nebula, a planetary.

Sir William Herschel, following ideas by earlier theorists, wondered whether the resolvable or starry nebulae might be external systems similar to our own Milky Way system. He never came to any definite conclusion about this, and seems to have changed his mind several times, but at least he had sown the seeds of a great idea. Later it was more or less discounted, and it was only the work of Hubble with the 100 in. Mount Wilson reflector in the 1920's which first proved that the starry nebulae are in fact separate galaxies. Henceforth, the term "spiral nebula" fell into discredit, to be replaced by the much more appropriate "galaxy". Incidentally, it should be noted that by no means all the galaxies are spiral in form.

Meanwhile, Dreyer's self-imposed task was to produce a new and more accurate list of nebulous objects, including clusters, gaseous nebulae, planetaries, and the "resolvable nebulae " which we now know to be galaxies. Having found discrepancies in Herschel's General Catalogue, he drew up a Supplement for his own use, and this was published while he was still at Birr Castle.54 It included all known corrections to the General Catalogue, and added 1172 objects to the 5079 which had been listed by Herschel. Most of these new discoveries had been made by D'Arrest, Marth, Stephan and Tempel, but some of them were due to Dreyer himself, who seems to have done most of the observing carried out with the Birr Castle telescopes during his period with Lord Rosse. The epoch for the Supplement was 1860.

The catalogue was a major work, but Dreyer was typically modest about it, and merely wrote later that the list "has, I believe, been found useful".60 Yet it did not satisfy him. A year after its publication, Lord Rosse published61 observations made at Birr between 1848 and 1878, none of which had been used by Herschel in the original list. Dreyer thereupon began preparing a second Supplement. At this point the Royal Astronomical Society stepped in.

The Royal Astronomical Society is the oldest astronomical body in the British Isles. It came into being in 1820 as the Astronomical Society of London, and, as has been noted, Sir William Herschel was its first President. (His papers published in the Monthly Notices are, of course, posthumous.) Since

* The modern literature about the Crab Nebula is voluminous. Recently it has been very much under study, since it is one of the most powerful radio sources in the sky and is also an X-ray emitter; but radio astronomy was utterly unknown in Dreyer's time. then the Society has maintained an unbroken active existence, and its publications are representative of British professional astronomy. In Dreyer's time, as now, it wielded immense authority, and it used this power wisely. The R.A.S. Council approached Dreyer, and asked whether he would combine all three catalogues - Sir John Herschel's original, Dreyer's 1877 supplement, and the new proposed supplement - into one, which would be issued as an R.A.S. Memoir.

Dreyer's Copy of the NGC

Dreyer agreed, and took the opportunity to make further revisions and checks. The work took a long time indeed, and required the greatest care, but at last all was ready, and in 1888 the "New General Catalogue of Nebulae and Clusters of Stars" appeared. The N.G.C. numbers were at once adopted, officially superseding the earlier Messier numbers. True, the Messier numbers are still popular - but they amount to only just over one hundred, while Dreyer's N.G.C. contained a grand total of 7840 objects; no nebulae or clusters known up to the end of the year 1887 were left out. Two extra sections followed later. In 1895 there appeared the first Index Catalogue or I.C.63, containing 1529 new nebulae and clusters found since 1887, and finally, in 1910, came the second Index Catalogue64, with 3857 objects discovered after 1895. In this last Index Catalogue, the epoch was given for 1900 as well as 1860, "by special desire" of the R.A.S. Council.

Drawing up lists of this kind is not merely a matter of noting down observations and putting them in order. Dreyer's contribution lay in "rigorous comparing, checking, weighing, re-measuring where necessary and possible, the results of the various observers so as to produce from all available data the most accurate catalogue possible"52. He succeeded well, and it is true to say that the N.G.C. represents his most important contribution to science, though he did much in other fields as well-particularly with regard to historical astronomy. And naturally enough, some of the personal credit earned by Dreyer was reflected by the domes of Armagh Observatory, where valuable observations, mainly with the new Grubb lOin. refractor, were going on all the time. Not only nebulous objects came under Dreyer's scrutiny; he records that after 1893 the refractor was also used for micrometrical measures of double stars, together with more occasional work on phenomena such as the 1895 transit of Mercury across the face of the Sun. 65

The production of the Second Armagh Catalogue of stars, and the classic N.G.C., meant that the Observatory had been firmly established as one of the leading astronomical centres in the British Isles. Yet in other respects all was not well. It is rather damping to turn back from the important work to the persistent money difficulties which had to be faced, but the ugly fact remained that the disestablishment of the Irish Church had left matters in a precarious state. There were also minor annoyances. For instance, in 1887 the income tax authorities suddenly informed the long-suffering Director that the twenty acres of land attached to Armagh Observatory were not, as had always been assumed, exempt from taxation. Dreyer had his own methods of dealing with the situation. He wrote in the Observatory Minute-book that when ordered to pay tax, "of course I declined . . . and as after further threats I still refused, I have been summoned to appear before the Commissioners of Income Tax on Friday next, when they will be in Armagh".4 He duly went, taking with him a letter to Dr. Robinson from the Board of Inland Revenue, dated from Somerset House on '13 December 1866, declaring quite categorically that the land really was exempt. He was bothered no more. Later, in 1905, he entered into battle against the local Water Board, who wanted to increase their rate from £2 to £4. In the 1906 entry in the Minute-Book he adds, triumphantly, that the Board had "apparently abandoned their claim". Truly Dreyer was cast in the mould of Romney Robinson, who had personally stopped three different railways!

Unfortunately, other difficulties could not be dealt with so firmly. An observatory needs money for its general upkeep, and Dreyer himself was not able to draw upon a large private income as earlier Directors had done. It is worth quoting the entry in the Minute Book for 1896,4 in which Dreyer wrote that although the instruments were in good repair, "the walls of the staircase of the East Tower are in a very dilapidated state, the plaster dropping off everywhere. This has been the case as long as I have been here, but the walls ought to be repaired and painted. I have got an estimate for this amounting to £3. 17. 2. If the floor-margin of the hall of the dwelling house could be repainted on the same occasion, it would greatly improve the appearance of the hall . . . this would cost 16s. 9d." It may seem strange that a world-famous institution such as Armagh Observatory could not afford an outlay of less than £5 for essential repairs, even bearing in mind that the pound was worth much more than it is now; but such was the position, and there was nothing that Dreyer could do about it.

Needless to say, there was no money to spare for an assistant astronomer, and after January 1885 Dreyer carried on alone - though in the meteorological work he had the part-time assistance of Faris, who was still keeping the weather records and apparently giving whatever other help he could. In late 1896 there came a new threat. Judicial rents were about to be fixed by the Land Court for another period of fifteen years, and, as expected, there were considerable reductions, amounting to some 30 per cent.

Something had to be done, and in 1897 Dreyer, via the Archbishop of Armagh, appealed to the Treasury for official help. In an eloquent Memorandum, it was pointed out that after the new rent decreases, the yearly income of the Observatory would again be drastically reduced, which would cut the Director's salary from £270 to well below the £200 mark and would leave nothing for the provision of an assistant, the purchase of new equipment, or even the maintenance of the existing buildings. The grant applied for was a modest £300, but even so it met with a chilly response. In July 1897, the Lords Commissioners of the Treasury wrote that they "were not prepared, either. upon grounds of equity or upon the merits of the case, to apply to Parliament for a grant in aid of the Observatory". Dreyer then asked for support from the Royal Society, and met with another blank refusal. In all fairness, however, it must be added that in 1899 the Royal Society did provide £70 towards the cost of a micrometer-microscope for measuring photographic plates, and the instrument, of Troughton & Simms make, proved to be most useful. Working from some of the fine photographs taken in England by Dr. Isaac Roberts, Dreyer put the micrometer-microscope to use, and in 1904 published a complete survey of the positions of all stars and other objects within 25 minutes of arc of the centre of the spiral galaxy in Triangulum66. But this £70 was a mere drop in the financial ocean, and the general situation continued to be very difficult indeed.

So far as the rents were concerned, it seemed that still further reductions would be inevitable in the future; the era of soaring prices and wages had not then begun. In 1906 the tenants of Derrynaught agreed to purchase their holdings at a reduction of 4s. in the pound, and to add one year's rent to the purchase money. At last, in February 1914, the estate of Derrynaught finally passed out of the Governors' hands, exactly 120 years after it had been purchased by Primate Robinson as an endowment for the resident astronomer at the Observatory. Similar action was taken with the Carlingford estate, though the two tenants of Tullynure in County Tyrone proved less amenable. At least this action put an end to the steady shrinkage of the total income of the Observatory, though it was a far from satisfactory solution.

There were some repercussions - for instance, it is on record4 that the Rev. J. Kingsborough of Kildarton wrote to the Governors protesting at the withdrawal of his yearly £3, and his letter was couched in no uncertain terms, since he said that "the loss has fallen upon us with a heavy and depressing weight, as you are all supposed to be friends and not enemies". The Governors, having discussed the matter, gave Mr. Kingsborough his £3 for the year 1914, but regretted 1hat they could not continue the annual payment, as they had no money to do so.

All in all, Armagh Observatory had to be run upon a shoestring, and it is greatly to Dreyer's credit that papers and contributions kept on appearing in the scientific literature of the time. For instance, there were notes on nebular positions67, reduction problems, and some extra stars in the Armagh Catalogue68, and the 1900 partial eclipse of the Sun69. Another partial eclipse was timed in 191470. In the same year, the transit of Mercury was watched with the lOin. refractor.71 Dreyer records that at 12h 10m G.M.T., while the transit was in progress, a white point was seen north of Mercury's centre; but as it had reached the middle of Mercury's disk by 01h 52m G.M.T., it was clearly nothing more than an optical effect.

Another striking object was the great comet of 1910, which was observed from Armagh as often as possible. Halley's Comet, on the other hand, "turned out to be a disappointment . . . no details whatsoever could be seen, and only the beginning of the tail close to the bright nucleus"4.

Despite the financial difficulties, Dreyer managed to keep the actual observing instruments in good order, because he did most of the repair work himself. For instance, he renovated the old transit instrument, and found that it was in excellent condition even though it had been left unused for two decades prior to 1890. The papier-mache covering of the Robinson Dome over the lOin. refractor was renewed in 1900 with much better material, and so far as this part of the Observatory's situation was concerned the outlook was fairly promising - apart from the fact that there was no money to buy the new equipment needed for more modern branches of research. Dreyer regretted this profoundly. But as well as looking into the future, he also examined the past, and he will always be remembered for his work on historical astronomy as well as for his numerous other contributions.

Dreyer, remember, was a Dane; and he had always been fascinated by that earlier Danish astronomer, Tycho Brahe. Tycho's theory of the universe, according to which the planets moved round the Sun while the Sun itself travelled round the Earth, was untenable, and Dreyer's comprehensive historical book72 had dealt with it as well as with all the other hypotheses that had been put forward before scientists in general were forced to admit that our world is a totally unimportant planet. But Tycho was also one of the best astronomical observers of all time; had he had the advantage of telescopes, there is no knowing what he might have accomplished.

As early as 1890 Dreyer had published a book about Tycho,73 but this, valuable though it was, fell short of the ideal of collecting and printing all the observations of planets and fixed stars made by Tycho between 1563 and his death in 1601. As Dreyer himself said74, the observations had been formerly published only in an edition which was both incomplete and full of errors. The manuscripts were kept in the Royal Library at Copenhagen, and from 1908 the volumes were sent to Armagh one at a time so that they could be copied, while the French Government loaned an old manuscript copy from the Paris Observatory - where, two centuries earlier, full publication of the observations had been planned but never carried through.

The labour involved was immense. On this occasion there were no financial troubles, since the Carlsberg Fund, administered by the Royal Danish Academy of Sciences, defrayed the whole cost, but, inevitably, the work took up much of Dreyer's time; it led, in the long run, to his resignation from Armagh. Three of the fifteen volumes of the whole series were published while he was still Director, but the rest came during the last period of his life, spent at Oxford. All sorts of important facts emerged. For instance, one paper by Dreyer showed clearly that Tycho was only too well aware of the uncertainty of the value of the solar parallax (that is to say, the distance between the Earth and the Sun) even though he had never been able to follow it up.75

Another historical venture was undertaken in 1910, when the Royal Society and the Royal Astronomical Society appointed a committee to prepare an edition of the collected works of Sir William Herschel. Dreyer was a member of the Committee, and eventually became Editor. All the available Herschel material was re-examined, and the observations checked; Dreyer personally made many measures with the lOin. at Armagh in order to clear up doubtful points. He also wrote a long biographical introduction, and the finished book, published in 191276, was due largely to his labours.

As we have noted, Sir William Herschel had been the first President of the Royal Astronomical Society. It was therefore fitting that in 1916 the Society should award Herschel's biographer and editor its highest honour, the Gold Medal. The award was made for Dreyer's historical work - and only one other Medallist, Robert Grant in 1866, had ever been given the Gold Medal for this type of research. The President in 1916 was Professor R. A. Sampson, and one paragraph of his presentation address is worth remembering: "Dr. Dreyer, we would not rob Denmark of you, but you have so long been one of us that we have absorbed you, speech and person. We have watched with admiration your labours . . . we trust that, with good health, they may be long continued."

In point of fact Dreyer had another ten years of active life ahead of him, but not, regrettably for Ireland, at Armagh. He had made up his mind to devote his main time to the Tycho research, and it was absolutely essential for him to have access to major libraries, chiefly the Bodleian at Oxford. He had a great decision to make, and, with typical firmness, he made it. In 1916 he informed the Governors that he must resign his Directorship, so that he could go to live in England to complete his historical work. Obviously his resignation had to be accepted, albeit with the greatest regret - and after a fruitful regime of 34 years, Dreyer's official association with Armagh came to an end. He went to Oxford, and remained there until his death on 14 September 1926. Honours were showered upon him; until the last year of his life he remained in excellent health, and as well as the Tycho work he also published numerous other papers. He collaborated with H. H. Turner in the official History of the Royal Astronomical Society77, and it was appropriate, too, that he should be made President for the 1923-5 period; he was a worthy successor to Herschel and other great astronomers who had occupied the Presidential chair.

Dreyer died forty years ago, and had been away from Armagh for ten years before that, but there are still many people in the cathedral city who remember him. With his striking white beard, he looked very much like the conventional (even if often false) picture of an astronomer. All who knew him speak of his courteous, kindly and dignified nature, and there are many who received active help from him. One small instance may be cited here, because it can be given personally by the writer of this history. A little while ago, in late 1965, I was at a Boy Scout meeting in Armagh, in my capacity of local badge-secretary, and there I was talking to a man who had been the first Assistant Scoutmaster at Armagh in the very early days of the movement. He told me how he had been to see Dreyer - it must have been around 1910 - and had asked him to come and talk to the boys. Dreyer was delighted to accept, and spent a great deal of time and patience explaining to the Scouts what astronomy was all about.

A Director such as Dreyer would clearly be hard to replace with any degree of adequacy, and the Primate - Archbishop Crozier - and the Governors gave long and careful thought to the question of a successor. For a few months Faris, who had been associated with the Observatory for so long, was in nominal charge, and was even paid an extra £50 in addition to his annual £50 as meteorological assistant. Then the decision was made. The choice fell upon Joseph Alfred Hardcastle.

     

Last Revised: 2013 July 18th