So strong and gifted a man as Airy was bound to make enemies, and at different times of his life bitter attacks were made on him from one quarter or another. One of these, curiously enough, was from Sir James South, the man who, as he said, first introduced him to practical astronomy. Later came the discovery of Neptune, and Airy was subjected to much bitter criticism, since, as it appeared on the surface, it was owing to his supineness that Adams missed being held the sole discoverer of the new planet, and narrowly missed all credit for it altogether. Last of all was the vehement attack made upon him by Richard Anthony Proctor, in connection with his preparations for the transit of Venus. All such attacks, however, simply realized the old fable of the viper and the file. Attacks which would have agonized Flamsteed's every nerve, and have called forth full and dignified rejoinders from Maskelyne, were absolutely and entirely disregarded by Airy. He had done his duty, and in his own estimation—and, it should be added, in the estimation of those best qualified to judge—had done it well. He was perfectly satisfied with himself, and what other people thought or said about him influenced him no more than the opinions of the inhabitants of Saturn.

But great as Airy was, he had the defects of his qualities, and some of these were serious. His love of method and order was often carried to an absurd extreme, and much of the time of one of the greatest intellects of the century was often devoted to doing what a boy at fifteen shillings a week could have done as well, or better. The story has often been told, and it is exactly typical of him, that on one occasion he devoted an entire afternoon to himself labelling a number of wooden cases 'empty,' it so happening that the routine of the establishment kept every one else engaged at the time. His friend Dr. Morgan jocularly said that if Airy wiped his pen on a piece of blotting-paper he would duly endorse the blotting-paper with the date and particulars of its use, and file it away amongst his papers. His mind had that consummate grasp of detail which is characteristic of great organizers, but the details acquired for him an importance almost equal to the great principles, and the statement that he had put a new pane of glass into a window would figure as prominently in his annual report to the Board of Visitors as the construction of the new transit circle. His son remarks of him that 'in his last days he seemed to be more anxious to put letters which he received into their proper place for reference than even to master their contents,' his system having grown with him from being a means to an end, to becoming the end itself.

So, too, his regulation of his subordinates was, especially in his earlier days, despotic in the extreme—despotic to an extent which would scarcely be tolerated in the present day, and which was the cause of not a little serious suffering to some of his staff, whom, at that time, he looked upon in the true spirit of Pond, as mere mechanical 'drudges.' For thirty-five years of his administration the salaries of his assistants remained discreditably low, and his treatment of the supernumerary members of his staff would now probably be characterized as 'remorseless sweating.' The unfortunate boys who carried out the computations of the great lunar reductions were kept at their desks from eight in the morning till eight at night, without the slightest intermission, except an hour at midday. As an example of the extreme detail of the oversight which he exercised over his assistants, it may be mentioned that he drew up for each one of those who took part in the Harton Colliery experiment, instructions, telling them by what trains to travel, where to change, and so forth, with the same minuteness that one might for a child who was taking his first journey alone; and he himself packed up soap and towels with the instruments, lest his astronomers should find themselves, in Co. Durham, out of reach of these necessaries of civilization.

A regime so essentially personal may indeed have been necessary after Pond's administration, and to give the Observatory a fresh start. But it would not have been to the advantage of the Observatory, had it become a permanent feature of its administration, as it militated—was almost avowedly intended to militate—against the growth of real zeal and intelligence in the staff, and necessarily occasioned labour and discomfort out of proportion to the results obtained. Fortunately, in Airy's later years, the extension of the work of the Observatory, a slight failing in his own powers, and the efforts he was devoting to the working out of the lunar theory, compelled him to relax something of that microscopic imperiousness which had been the chief characteristic of his rule for so long.

Airy had, in the fullest degree, the true spirit of the public servant; his sense of duty to the State was very high. He was always ready to undertake any duty which he felt to be of public usefulness, and many of these he discharged without fee or reward.

So great an astronomer was necessarily most highly esteemed by astronomers. He was President of the Royal Society for two years; he was five times President of the Royal Astronomical Society, and twice received its gold medal, beside a special testimonial for his reduction of the Greenwich lunar observations. From the Royal Society he received the Copley medal and the Royal medal, beside honorary titles from the Universities of Oxford, Cambridge, and Edinburgh. So invaluable a public servant, he received the distinction of a Knight Commandership of the Bath in 1872. He had been repeatedly offered knighthood before, but had not thought it well to receive it. He was in the receipt of decorations also from a great number of foreign countries; for, for many years, he was looked up to, not only by English astronomers, but by scientific men in all countries, as the very head and representative of his science.

And he also received a more popular appreciation—and most justly so. For whilst no one could have less of the arts of the ordinary popularizer about him, no one has ever given popular lectures on astronomy which more fully corresponded to the ideal of what such should be than Airy's six lectures to working men, delivered at Ipswich. And we may count the bestowal upon him of the honorary freedom of the City of London, in 1875, as one of the tokens that his services in this direction had not been unappreciated.

During the last seven years of his official career he undertook the working out of a lunar theory, and, to allow himself more leisure for its completion, he resigned his position August 15, 1881, after forty-six years of office. He was now eighty years of age, and he took up his residence at the White House, just outside Greenwich Park. He resided there till his death, more than ten years later—January 2, 1892.

Airy was succeeded in the Astronomer Royalship by the present and eighth holder of the office, W. H. M. Christie. He was born at Woolwich, in 1845, his father having been Professor Samuel Hunter Christie, F.R.S. He was educated at King's College, London, and Trinity College, Cambridge, graduating as fourth Wrangler in 1868. In 1870 he was appointed chief assistant at Greenwich, in succession to Mr. Stone, who had become her Majesty's astronomer at the Cape, and in 1881 he succeeded Airy as Astronomer Royal.

During Mr. Christie's office, the two new departments of the Astrographic Chart and Double-star observations have come into being. The following buildings have been erected under his administration: the great New Observatory in the south ground, the New Altazimuth, the New Library, nearly opposite to it, the Transit Pavilion, the porter's lodge, and the Magnetic Pavilion out in the Park. Whilst in the old buildings the Astrographic dome has been added, and the Upper and Lower Computing rooms have been rebuilt and enlarged. As to the instruments, the 28-inch refractor, the astrographic twin telescope, the new altazimuth, the 26-inch and 9-inch Thompson photographic refractors, and the 30-inch reflector are all additions during the present reign. Roughly speaking, therefore, we may say that three-fourths of the present Observatory has been added during the nineteen years of the present Astronomer Royal. One exceedingly important improvement should not be overlooked. Airy observed little himself whilst at Greenwich, and had an inadequate idea of the necessity for room in a dome and breadth in a shutter-opening. With the sole exception, perhaps, of the transit circle, every instrument set up by Airy was crammed into too small a dome or looked out through too narrow an opening. The increase of shutter-opening of the newer domes may be well seen by contrasting, say, the old altazimuth or the Sheepshanks dome with that of the astrographic. This reform has had much to do with the success of later work.

CHAPTER V

THE OBSERVATORY BUILDINGS

Like a living organism, Greenwich Observatory bears the record of its life-history in its structure. It was not one of those favoured institutions that have sprung complete and fully equipped from the liberality of some great king or private millionaire. As we have seen, it was originally established on the most modest—not to say meagre—scale, and has been enlarged just as it has been absolutely necessary. To quote again from Professor Newcomb—

'Whenever any part of it was found insufficient for its purpose, new rooms were built for the special object in view, and thus it has been growing from the beginning by a process as natural and simple as that of the growth of a tree. Even now the very value of its structure is less than that of several other public observatories, though it eclipses them all in the results of its work.'

Entering the courtyard—an enclosure some eighty feet deep by ninety feet in extreme breadth—by the great gate, we see before us Flamsteed House, the original building of the Observatory. Flamsteed's little domain was only some twenty-seven yards wide by fifty deep, and for buildings comprised little beyond a small dwelling-house on the ground floor, and one fine room above it. This room—the original Greenwich Observatory—still remains, and is used as a council room by the official Board of Visitors, who come down to the Observatory on the first Saturday in June, to examine into its condition and to receive the Astronomer Royal's report. The room is called, from its shape, the Octagon Room, and is well known to Londoners from the great north window which looks out straight over the river between the twin domes of the Hospital.

In Bradley's time, about 1749, the first extension of the domains of the Observatory took place to the south and east of the original building, the direction in which, on the whole, all subsequent extensions have taken place, owing to the fact that the original building was constructed at the extremity of what Sir George Airy was accustomed to call a 'peninsula'—a projecting spur of the Blackheath plateau, from which the ground falls away very sharply on three sides and on part of the fourth.

The Observatory domain at present is fully two hundred yards in greatest length, with an average breadth of about sixty. Nearly the whole of this accession took place under the directorates of Pond and Airy. The present instruments are, therefore, as a rule, the more modern in direct proportion to their distance from the Octagon Room—the old original Observatory. There is one notable exception. The very first extension of the Observatory buildings, made in the time of Halley, the second Astronomer Royal, consisted in the setting up of a strong pier, to carry two quadrant telescopes. The pier still remains, but now forms the base of the support of the twin telescopes devoted to the photographic survey of the heavens for the International Chart.

Standing just within the gate of the courtyard, and looking westward, that is toward Flamsteed House, we have immediately on our right hand the porter's lodge; a little farther forward, also on the right, the Transit Pavilion, a small building sheltering a portable transit instrument; and farther forward, still on the right, the entrance to the Chronograph Room. Above the Chronograph Room is a little, inconveniently-placed dome, containing a small equatorially-mounted telescope, known as the Shuckburgh. Beyond the Chronograph Room a door opens on to the North Terrace, over which is seen the great north window of the Octagon Room. Close by the door of the Chronograph Room a great wooden staircase rises to the roof of the main building. It is not an attractive-looking ascent, as the steps overlap inconveniently. Still, there is no record of an accident upon them, and those who venture on the climb to the roof, where are placed the anemometers and the turret carrying the time-ball, which is dropped daily at 1 p.m., will be well repaid by the splendid view of the river which is there afforded to them.

Passing under this staircase, on the wall by its side is seen the following inscription:—

Carolus II^s Rex Optimus
Astronomiæ et Nauticæ artis
Patronus Maximus
Speculam hanc in utriusque commodum
fecit
Anno D^NI MDCLXXVI. Regni sui XXVIII.

Curante Iona Moore milite
R. T. S. G.

Coming back into the courtyard, and crossing the face of the Astronomer Royal's private house, the range of buildings is reached which form the left hand or south side of the enclosure. Entering the first of these, we find ourselves in the Lower Computing Room, which is devoted to the 'Time Department.' The next room which opens out of it, as we turn eastwards, was Bradley's Transit Room, but is now used for the storage of chronometers. Passing through Bradley's Transit Room, we come to the present Transit Room, which brings us close to the great gate. The range of buildings is, however, continued somewhat farther, containing on the ground floor some small sitting-rooms and a fire-proof room for records.

Turning back to the Lower Computing Room, we notice in it the stone pier, already alluded to, which was set up by Halley, and formed the first addition to the original Observatory of Flamsteed. The Lower Computing Room itself and Bradley's Transit Room were due to the Astronomer after which the latter is named. An iron spiral staircase in the middle of the Lower Computing Room leads up to the Upper Computing Room, and above that to the Astrographic dome, so called because the twin telescope housed therein is devoted to the work of the Astrographic Chart—a chart of the entire sky to be made by eighteen co-operating observatories by means of photography. In this way it is intended to secure a record of the places of far more stars than could be done by the ordinary methods, and in this project Greenwich has necessarily taken a premier place. This is a work which, whilst it is the legitimate and natural outcome of the original purpose of the Observatory, is yet pushed beyond what is necessary for any mere utilitarian assistance to navigation. For the sailor it will always be sufficient to know the places of a mere handful of the brightest stars, and the vast majority of those in the great photographic map will never be visible in the little portable telescope of the sailor's sextant. But it will be freely admitted that in the case of an enterprise of this nature, in which the observatories of so many different nations were uniting, and which was so precisely on the lines of its original charter, though an extension of it, it was impossible for Greenwich to hold back on the plea that the work was not entirely utilitarian.

Descending again to the Lower Computing Room, and passing through it, not to the east, into Bradley's Transit Room, but through a little lobby to the south, we come upon an inconvenient wooden staircase winding round a great stone pillar with three rays. This pillar is the support of Airy's altazimuth, and very nearly marks the place where Flamsteed set up his original sextant.

Returning again to the Lower Computing Room, and passing out to the east, just in front of the Time Superintendent's desk, we enter a small passage running along the back of Bradley's Transit Room, and from this passage enter the present Transit Room near its south end. Just before reaching the Transit Room, however, we pass the Reflex Zenith Tube, a telescope of a very special kind.

Immediately outside the Transit Room is a staircase leading on the first floor to two rooms long used as libraries, and to the leads above them, on which is a small dome containing the Sheepshanks equatorial. These libraries are over the small sitting-rooms already referred to. The fire-proof Record Rooms, two stories in height, terminate this range of buildings.

Beyond the Record Rooms the boundary turns sharply south, where stands a large octagonal building surmounted by a dome of oriental appearance, a 'circular versatile roof,' as the Visitors would have called it a hundred years ago. This dome—which has been likened, according to the school of æsthetics in which its critics have been severally trained, to the Taj at Agra, a collapsed balloon, or a mammoth Spanish onion—houses the largest refractor in England, the 'South-east Equatorial' of twenty-eight inches aperture. But, though the largest that England possesses, it would appear but as a pigmy beside some of the great telescopes for which America is famous.

Beyond this dome the hollow devoted to the Astronomer Royal's private garden reduces the Observatory ground to a mere 'wasp's waist,' a narrow, inconvenient passage from the old and north observatory to the younger southern one.

The first building, as the grounds begin to widen out to the south, contains the New Altazimuth, a transit instrument which can be turned into any meridian. A library of white brick and a low wooden cruciform building—the Magnetic Observatory—follow it closely.

This latter building houses the Magnetic Department, a department which, though it lies aside from the original purposes of the Observatory, as defined in the warrant given to Flamsteed, is yet intimately connected with navigation, and was founded by Airy very early in his period of office. This deals with the observation of the changes in the force and direction of the earth's magnetism, an inquiry which the greater delicacy of modern compasses, and, in more recent times, the use of iron instead of wood in the construction of ships, has rendered imperative.

Closely associated with the Magnetic Department is the Meteorological. Weather forecasts, so necessary for the safety of shipping round our coasts, are not issued from Greenwich Observatory, any more than the Nautical Almanac is now issued from it. But just as the Observatory furnishes the astronomical data upon which the almanac is based, so also a considerable department is set apart for furnishing observations to be used by the Meteorological Office at Westminster for their daily predictions.

So far, the development of the Observatory had been along the central line of assistance to navigation. But the 'Magnetic Department' led on to a new one, which had but a secondary connection with it. It had been discovered that the extent of the daily range of the magnetic needle, and the amount of the disturbances to which it was subjected, were in close connection with the numbers and size of the spots on the sun's surface. This led to the institution of a daily photographic record of the state of the sun's surface, a record of which Greenwich has now the complete monopoly.

This 'New Observatory,' like the old, and like the great South-eastern tower, is an octagon in its central portion. But whilst the two other great buildings are simply octagonal, here the octagon serves only as the centre from which radiate four great wings to the four points of the compass. The building is by far the largest on the ground, but in little accord with the popular idea of an astronomer as perpetually looking through a telescope, carries but a single dome; its best rooms being set apart as 'computing rooms,' for the use of those members of the staff who are employed in the calculations and other clerical work, which form, after all, much the greater portion of the Observatory routine.

An observer with the transit instrument, for instance, will take only three or four minutes to make a complete determination of the place of a single star. But that observation will furnish work to the computers for many hours afterwards. Or, to take a photograph of the sun will occupy about five minutes in setting the instrument, whilst the actual exposure will take but the one-thousandth part of a second. But the plate, once exposed, will have to be developed, fixed, and washed; then measured, and the measures reduced, and, on the average, will provide one person with work for four days before the final results have been printed and published.

It is easy to see, then, that observing, though the first duty of the Observatory, makes the smallest demand on its time. The visitor who comes to the Observatory by day (and none are permitted to do so by night) finds the official rooms not unlike those of Somerset House or Whitehall, and its occupants for the most part similarly engaged in what is, apparently, merely clerical work. An examination of the big folios would of course show that instead of being ledgers of sales of stamps, or income-tax schedules, they referred to stars, planets, and sun-spots; but for one person actively engaged at a telescope, the visitor would see a dozen writing or computing at a desk.

The staff, like the building, is the result of a gradual development, and bears traces of its life history in its composition. First comes the Astronomer Royal, the representative and successor of the original 'King's Astronomer,' the Rev. John Flamsteed. But the 'single surly and clumsy labourer,' which was all that the 'Merry Monarch' could grant for his assistance, is now represented by a large and complex body of workers; each varied class and rank of which is a relic of some stage in the progress of the Observatory to its present condition.

The following extract from the Annual Report of the Astronomer Royal to the Board of Visitors, June, 1900, describes the present personnel of the establishment:—

'The staff at the present time is thus constituted, the names in each class being arranged in alphabetical order:—

'Chief assistants—Mr. Cowell, Mr. Dyson.

'Assistants—Mr. Hollis, Mr. Lewis, Mr. Maunder, Mr. Nash, Mr. Thackeray.

'Second-class assistants—Mr. Bryant, Mr. Crommelin.

'Clerical assistant—Mr. Outhwaite.

'Established computers—Mr. Bowyer, Mr. Davidson, Mr. Edney, Mr. Furner, Mr. Rendell, and one vacancy.

'The two second-class assistants will be replaced by higher grade established computers as vacancies occur.

'Mr. Dyson and Mr. Cowell have the general superintendence of all the work of the Observatory. Mr. Maunder is charged with the heliographic photography and reductions, and with the preparation of the Library Catalogue. Mr. Lewis has charge of the time-signals and chronometers, and of the 28-inch equatorial. Mr. Thackeray superintends the miscellaneous astronomical computations, including the preparation of the new Ten-Year Catalogue. Mr. Hollis has charge of the photographic mapping of the heavens, the measurement of the plates, and the computations for the Astrographic Catalogue. Mr. Crommelin undertakes the altazimuth and Sheepshanks equatorial reductions, and Mr. Bryant the transit and meridian zenith distance reductions and time-determinations. In the magnetic and meteorological branch, Mr. Nash has charge of the whole of the work. Mr. Outhwaite acts as responsible accountant officer; has charge of the library, records, manuscripts, and stores, and conducts the official correspondence. As regards the established computers, Mr. Bowyer, Mr. Furner, Mr. Davidson, and Mr. Rendell assist Mr. Lewis, Mr. Thackeray, Mr. Hollis, and Mr. Bryant respectively, and Mr. Edney assists Mr. Nash.

'There are at the present time twenty-four supernumerary computers employed at the Observatory, ten being attached to the astronomical branch, two the chronometer branch, six to the astrographic, one to the heliographic, four to the magnetic and meteorological, and one to the clerical.

'A foreman of works, with two carpenters, and two labourers; a skilled mechanic with an assistant; a gate porter, two messengers, a watchman, a gardener, and a charwoman, are also attached to the Observatory.

'The whole number of persons regularly employed at the Observatory is fifty-three.'

The day work, as said before, is by far the greatest in amount, the 'office hours' being from nine till half-past four, with an hour's interval. The arrangements for the night watches present some complications.

For many years the instruments in regular use were two only, the transit circle and the altazimuth. The arrangements for observing were simple. Four assistants divided the work between them thus: an assistant was on duty with the transit circle one day, his watch beginning about six a.m. or a little later, and ending about three the following morning; a watch of twenty-one hours in maximum length. The second day his duties were entirely computational, and were only two or three hours in length. The third day he had a full day's work on the calculations, followed by a night duty with the altazimuth. The latter instrument might give him a very easy watch or a terribly severe one. If the moon were a young one it was easy, especially if the night was clear, as in that case an hour was enough to secure the observations required.

Very different was the case with a full moon, especially in the long, often cloudy, nights of winter. Then a vigilant watch had to be kept from sunset to sunrise, so that in case of a short break in the clouds the moon might yet be observed. Such a watch was the severest (with one exception) that an assistant had to undergo.

His fourth day would then resemble his second, and with the fifth day a second cycle of his quartan fever would commence, the symptoms following each other in the same sequence as before.

Such a routine carried on with iron inflexibility was exceedingly trying, as it was absolutely impossible for an observer to keep any regularity in his hours of rest or times for meals.

This routine has been considerably modified by the present Astronomer Royal, partly because the instruments now in regular daily use are five instead of two, and partly because a less stringent system has proved not merely far less wearing to the observers, but also much more prolific of results. It was impossible for a man to be at his best for long under the old régime, and from forty-six to forty-seven has been an ordinary age for an assistant to break down under the strain.

One point in which the observing work has been lightened has been in the discontinuance of the altazimuth observations at the full of the moon, another in the shortening of the hours of the transit circle watch; and a further and most important one in the arrangement that the observers with the larger instruments should have help at their work. The net result of these changes has been a most striking increase in the amount of work achieved. Thus, whilst in the year ending May 20, 1875, 3780 transits were taken with the transit circle, and 3636 determinations of north polar distance; in that ending May 10, 1895, the numbers had risen to 11,240 and 11,006 respectively, the telescope remaining precisely the same.

One principle of Airy's rule still remains. So far as possible no observer is on duty for two consecutive days, but a long day of desk work and observing is followed by a short day of desk work without observing.

It will be readily understood that with five principal telescopes in constant work and one or two minor ones, some demanding two observers, others only one, each telescope having its special programme and its special hours of work, whilst by no means every member of the staff is authorized to observe with all instruments indifferently, it becomes a somewhat intricate matter to arrange the weekly rota in strict accordance with the foregoing principle, and with the further one, that whilst a considerable amount of Sunday observing is inevitable, the average duty of an observer should be three days a week, not seven days a fortnight. There is a story, received with much reserve at Cambridge, that there was once a man at that university who had mastered all the colours and combinations of shades and colours of the various colleges and clubs. If so gifted a being ever existed, he may be paralleled by the Greenwich assistant who can predict for any future epoch the sequence of duties throughout the entire establishment. At any rate, one of the first items in the week's programme is the preparation of the rota for the week, or rather, to use an ecclesiastical term, for the 'octave,' i.e. from the Monday to the Monday following.

The special work to be carried out on any telescope is likewise a matter of programme. For the transit circle a list of the most important objects to be observed is supplied for the observer's use, and the general lines upon which the other stars are to be selected from a huge 'Working Catalogue' are well understood. With some of the other telescopes the principles upon which the objects are to be selected are laid down, but the actual choice is left to the discretion of the observer at the time. There is no time for the watcher to spend in what the outsider would regard as 'discovery'; such as sweeping for comets or asteroids, hunting for variable stars, sketching planets, and so forth. Indeed, there is a story current in the Observatory that some fifty years ago, when the tide of asteroid discovery first set in, Airy found an assistant, since famous, working with a telescope on his 'off-duty' night. That stern disciplinarian asked what business the assistant had to be there on his free night, and on being told he was 'searching for new planets,' he was severely reprimanded and ordered to discontinue at once. A similar energy would not meet so gruff a discouragement to-day; but the routine work so fully occupies both staff and telescopes that an assistant may be most thoroughly devoted to his science, and yet pass a decade at the Observatory without ever seeing those 'show places' of the sky which an amateur would have run over in the first week after receiving his telescope. For example, there is no refractor in the British Isles so competent to bring out the vivid green light of the great Orion nebula—that marvellous mass of glowing, curdling, emerald cloud—or the indescribable magnificence of the myriad suns that cluster like swarming bees or the grapes of Eshcol in the constellation of Hercules; yet probably most of the staff have never seen either spectacle through it. The professional astronomer who is worth his salt will find abundance of charm and interest in his work, but he will not,

consider the charm to lie mainly in the occasional sight of wonderful beauty which his work may bring to him, nor the interest in some chance phenomenon which may make his name known.

It is not every field of astronomy that is cultivated at Greenwich. The search for comets and for 'pocket planets' forms no part of its programme; and the occupation so fascinating to those who take it up, of drawing the details on the surfaces of the moon, Mars, Jupiter, or Saturn, has been but little followed. Such work is here incidental, not fundamental, and the same may be said of certain spectroscopic observations of new or variable stars, and of many similar subjects. Work such as this is most interesting to the general public, and is followed with much devotion by many amateur astronomers. For that very reason it does not form an integral part of the programme of our State observatory. But work which is necessary for the general good, or for the advancement of the science, and which demands observations carried on continuously for many years, and strict unity of instruments and methods, cannot possibly be left to chance individual zeal, and is therefore rightly made the first object at Greenwich.

Those striking discoveries which from time to time appeal strongly to the popular imagination, and which have rendered so justly famous some of the great observatories of the sister continent, have not often been made here.

Its work has, none the less, been not only useful but essential. A century ago, when we were engaged in the hand-to-hand struggle with Napoleon, by far the most brilliant part of that naval war which we waged against the French, and the most productive of prize-money, was carried on by our cruisers, who captured valuable prizes in every sea. But a much greater service, indeed an absolutely vital one, was rendered to the State by those line-of-battle ships which were told off to watch the harbours wherein the French fleet was taking refuge. This was a work void of the excitement, interest, and profit of cruising. It was monotonous, wearing, and almost inglorious, but absolutely necessary to the very existence of England. So the continuance for more than two centuries of daily observations of places of moon, stars, and planets is likewise 'monotonous, wearing, and almost inglorious;' the one compensation is that it is essential to the life of astronomy.

The eight Astronomers Royal have, as already said, kept the Observatory strictly on the lines originally laid down for it, subject, of course, to that enlargement which the growth of the science has inevitably brought. But had they been inclined to change its course, the Board of Visitors has been specially appointed to bring them back to the right way. As already mentioned in the account of Flamsteed, the Board dates from 1710, when it practically consisted of the President and Council of the Royal Society. Its Royal warrant lapsed on the death of Queen Anne, and was not renewed at the accession of the two following sovereigns; but in the reign of George III. a new warrant was issued under date February 22, 1765; and this was renewed at the accession of George IV. When William IV. came to the throne, the constitution of the Board was extended, so as to give a representation to the new Royal Astronomical Society, founded in 1820. The President of the Royal Society is still chairman of the Board, but the Admiralty, of which the Observatory is a department, the two Universities of Oxford and Cambridge, and the Royal Astronomical Society are all represented on it by ex officio members, and twelve other members are contributed by the Royal and Royal Astronomical Societies respectively, six by each. The first Saturday in June is the appointed day for the annual inspection by the Board, and for the presentation to it of the Astronomer Royal's Report. To this all-important business meeting has been added something of a social function, by the invitation of many well-known astronomers and the leading men of the allied sciences to inspect the results of the year, and to partake of the chocolate and cracknels, which have been the traditional refreshments offered on these occasions for a period 'whereof the memory of man runneth not to the contrary.'

CHAPTER VI

THE TIME DEPARTMENT

One day two Scotchmen stood just outside the main entrance of Greenwich Observatory, looking intently at the great twenty-four-hour clock, which is such an object of attention to the passers through the Park. 'Jock,' said one of them to the other, 'd'ye ken whaur ye are?' Jock admitted his ignorance. 'Ye are at the vara ceentre of the airth.'

Geographers tell us that there is a sense in which this statement as it stands may be accepted as true. For if the surface of the globe be divided into two hemispheres, so related to each other that the one contains as much land as possible, and the other as little, then London will occupy the centre or thereabouts of the hemisphere with most land.

This was not, however, what the Scotchman meant. He meant to tell his companion that he was standing on the prime meridian of the world, the imaginary base line from which all distances, east or west, are reckoned; in short, that he was on 'Longitude Nought.'

He was not absolutely correct, however, for the great twenty-four-hour clock does not mark the exact meridian of Greenwich. To find the instrument which marks it out and defines it we must step inside the Observatory precincts, and just within the gate we see before us on the left hand a door which leads through a little lobby straight into the most important room of the whole Observatory—the Transit Room.

This room is not well adapted for representation by artist or photographer. Four broad stone pillars occupy the greater part of the space, and leave little more than mere passage room beside. Two of these pillars are tall, as well as broad and massive, and stand east and west of the centre of the room, carrying between them the fundamental instrument of the Observatory, the transit circle. The optical axis of this telescope marks 'Longitude Nought,' which is further continued by a pair of telescopes, one to the north of it, the other to the south, mounted on the third and fourth of the pillars alluded to above.

This room has not always marked the meridian of Greenwich, for it stands outside the original boundary of the Observatory. But it is only a few feet to the east of the first transit instrument which was set up by Halley, the second Astronomer Royal, in the extreme N.-W. corner of the Observatory domain, a distance equivalent to very much less than one-tenth of a second of time, an utterly insensible quantity with the instruments of two hundred years ago.

It would be a long story to tell in detail how the Greenwich transit room has come to define one of the two fundamental lines that encircle the earth. The other, the equator, is fixed for us by the earth itself, and is independent of any political considerations, or of any effort or enterprise of man. But of all the infinite number of great circles which could be drawn at right angles to the equator, and passing through the north and south poles, it was not easy to select one with such an overwhelming amount of argument in its favour as to obtain a practically universal acceptance. The meridians of Jerusalem and of Rome have both been urged, upon what we may call religious or sentimental grounds; that of the Great Pyramid at Ghizeh has been pressed in accordance with the fantastic delusion that the Pyramid was erected under Divine inspiration and direction; that of Ferro, in the Canaries, as being an oceanic station, well to the west of the Old World, and as giving a base line without preference or distinction for one nation rather than another.

The actual decision has been made upon no such grounds as these. It has been one of pure practical convenience, and has resulted from the amazing growth of Great Britain as a naval and commercial power. Like Tyre of old, she is 'situate at the entry of the sea, a merchant of the people for many isles,' and 'her merchants are the great men of the earth.' To tell in full, therefore, the steps by which the Greenwich meridian has overcome all others is practically to tell again, from a different standpoint, the story of the 'expansion of England.' The need for a supreme navy, the development of our empire beyond the seven seas, the vast increase of our carrying trade—these have made it necessary that Englishmen should be well supplied with maps and charts. The hydrographic and geographic surveys carried on, either officially by this country, or by Englishmen in their own private capacity, have been so numerous, complete, and far-reaching as not only to outweigh those of all other countries put together, but to induce the surveyors and explorers of not a few other countries to adopt in their work the same prime meridian as that which they found in the British charts of regions bordering on those which they were themselves studying. Naturally, the meridian of Greenwich has not only been adopted for Great Britain, but also for the British possessions over-sea, and, from these, for a large number of foreign countries; whilst our American cousins retain it, an historic relic of their former political connection with us. The victories of Clive at Arcot and Plassy, of Nelson at the Nile and Trafalgar, the voyages and surveys of Cook and Flinders, and many more; the explorations of Bruce, Park, Livingstone, Speke, Cameron, and Stanley; these are some of the agencies which have tended to fix 'Longitude Nought' in the Greenwich Transit Room.

There are two somewhat different senses in which the meridian of Greenwich is the standard meridian for nearly the entire world. The first is the sense about which we have already been speaking; it constitutes the fundamental line whence distances east and west are measured, just as distances north and south are measured from the equator. But there is another, though related sense, in which it has become the standard. It gives the time to the world.

There are few questions more frequently put than, 'What time is it?' 'Can you tell me the true time?' A stickler for exactitude might reply, 'What kind of time do you mean?' 'Do you mean solar or sidereal time?' 'Apparent time or mean time?' 'Local time or standard time?' There are all these six kinds of time, but it is only within the last two generations, within, indeed, the reign of our Sovereign, Queen Victoria, that the subject of the differences of most of these kinds of time has become of pressing importance to any but theorists.

In one of the public gardens of Paris a little cannon is set up with a burning-glass attached to it in such a manner that the sun itself fires the cannon as it reaches the meridian. This, of course, is the time of Paris noon—apparent noon—but it would be exceedingly imprudent of any traveller through Paris who wished, say, to catch the one o'clock express, to set his watch by the gun. For if it happened to be in February, he would find when he reached the railway station that the station clock was faster than the sun by nearly a full quarter of an hour, and that his train had gone; whilst towards the end of October or the beginning of November, he would find himself as much too soon.

Until machines for accurately measuring time were invented, apparent time—time, that is to say, given by the sun itself, as by a sun-dial—was the only time about which men knew or cared. But when reasonably good clocks and watches were made, it was very soon seen that at different times in the year there was a marked difference between sun-dial time and that shown by the clock, the reason being simply that the apparent rate of motion of the sun across the sky was not always quite the same, whilst the movement of the clock was, of course, as regular as it could be made.

This difference between time as shown by the actual sun and by a perfect clock is known as the 'equation of time.' It is least about April 15, June 15, August 31, and December 25. It is greatest, the sun being after the clock, about February 11; and the sun being before the clock, about November 2. Flamsteed, before he became Astronomer Royal, investigated the question, and so clearly demonstrated the existence, cause, and amount of the equation of time as entirely to put an end to controversy on the subject.

We had thus, early in the century, the two kinds of time in common use, apparent time and mean time, or clock time. But as the sun can only be on one particular meridian at any given instant, the time as shown by the clocks in one particular town will differ from that of another town several miles to the east or west of it. It is thus noon at Moscow 1 hr. 36 min. before it is noon at Berlin, and noon at Berlin 54 min. before it is noon in London.

This was all well enough known, but occasioned no inconvenience until the introduction of railway travelling; then a curious difficulty arose. Suppose an express train was running at the rate of sixty miles an hour from London to Bristol. The guard of the train sets his watch to London time before he leaves Paddington, but if the various towns through which the train passes, Reading, Swindon, etc., each keep their own local time, he will find his watch apparently fast at each place he reaches; but on his return journey, if he sets to Bristol time before starting, he will in a similar way find it apparently slow by the Swindon, Reading, and Paddington clocks as he reaches them in succession.

It became at once necessary to settle upon one uniform system of time for use in the railway guides. Apart from this, a passenger taking train, say, at Swindon, might have been very troubled to know whether the advertised time of his train was that of Exeter, the place whence it started, or Swindon, the station where he was getting in, or London, its destination. 'Railway time,' therefore, was very early fixed for the whole of Great Britain to be the same as London time, which is, of course, time as determined at Greenwich Observatory. At first it was the custom to keep at the various stations two clocks, one showing local time, the other 'railway,' or Greenwich time, or else the clocks would be provided with a double minute hand, one branch of which pointed to the time of the place, the other to the time of Greenwich.

It was soon found, however, that there was no sufficient reason for keeping up local time. Even in the extreme West of England the difference between the two only amounted to twenty-three minutes, and it was found that no practical inconvenience resulted from saying that the sun rose at twenty-three minutes past six on March 22, rather than at six o'clock. The hours of work and business were practically put twenty-three minutes earlier in the day, a change of which very few people took any notice.

Other countries besides England felt the same difficulty, and solved it in the same way, each country as a rule taking as its standard time the time of its own chief city.

There were two countries for which this expedient was not sufficient—the United States and Canada. The question was of no importance until the iron road had linked the Atlantic to the Pacific in both countries. Then it became pressing. No fewer than seventy different standards prevailed in the United States only some twenty years ago. The case was a very different one here from that of England, where east and west differed in local time by only a little over twenty minutes. In North America, in the extreme case, the difference amounted to four hours, and it seemed asking too much of men to call eight o'clock in their morning, or it might be four o'clock in their afternoon, their noonday.

The device was therefore adopted of keeping the minutes and seconds the same for all places right across the continent, but of changing the hour at every 15° of longitude. The question then arose what longitude should be adopted as the standard. The Americans might very naturally have taken their standard time from their great national observatory at Washington, or from that of their chief city, New York, or of their principal central city, Chicago. But, guided partly no doubt by a desire to have their standard times correspond directly to the longitudes of their maps, and partly from a desire to fall in, if possible, with some universal time scheme, if such could be brought forward, they fixed upon the meridian of Greenwich as their ultimate reference line, and defined their various hour standards as being exactly so many hours slow of Greenwich mean time.

The decision of the United States and of Canada brought with it later a similar decision on the part of all the principal States of Europe; and Greenwich is not only 'Longitude Nought' for the bulk of the civilized world, but Greenwich mean time, increased or decreased by an exact number of hours or half-hours, is the standard time all over the planet.

No; the statement requires correction. Two countries hold out, both close to our own doors. France, instead of adopting Greenwich time as such, adopts Paris time less 9 m. 21 s. (that being the precise difference in longitude between the two national observatories). Ireland disdains even such a veiled surrender, and Dublin time is the only one recognized from the Hill of Howth to far Valentia. So the distressful country preserves her old grievance, that she does not even get her time until after England has been served.

The alteration in national habits following on the adoption of this European system has had a very perceptible effect in some cases. Thus, Switzerland has adopted Mid-European time, one hour fast of Greenwich; the true local time for Berne being just half an hour later. The result of putting the working hours this thirty minutes earlier in the day has had such a noticeable effect on the consumption of gas, as to lead the gas company to contemplate agitating for a return to the old system.

Thus, Greenwich time, as well as the Greenwich meridian, has practically been adopted the world over.

It follows, then, that the determination of time is the most important duty of the Royal Observatory; and the Time Department, the one to which is entrusted the duty of determining, keeping, and distributing the time, calls for the first attention.

Entering the transit room, the first thing that strikes the visitor is the extreme solidity with which the great telescope is mounted. It turns but in one plane, that of 'longitude nought,' and its pivots are supported by the pair of great stone pillars which we have already spoken of as occupying the principal part of the transit-room area, and the foundations of which go deep down under the surface of the hill. On the west side of the telescope, and rigidly connected with it, is a large wheel some six feet in diameter, and with a number of wooden handles attached to it, resembling the steering-wheel of a large steamer. This wheel carries the setting circle, which is engraved upon a band of silver let into its face near its circumference, a similar circle being at the back of the wheel nearer the pillar. Eleven microscopes, of which only seven are ordinarily used, penetrate through the pier, and are directed on to this second circle.

The present transit is the fourth which the Observatory has possessed, and its three predecessors, known as Halley's, Bradley's, and Troughton's, respectively, are still preserved and hang on the walls of the transit room, affording by their comparison an interesting object-lesson in the evolution of a modern astronomical instrument.

The watcher who wishes to observe the passing of a star must note two things: he must know in what direction to point his telescope, and at what time to look for the star. Then, about two minutes before the appointed time, he takes his place at the eyepiece. As he looks in he sees a number of vertical lines across his field of view. These are spider-threads placed in the focus of the eye-piece. Presently, as he looks, a bright point of silver light, often surrounded by little flashing, vibrating rays of colour, comes moving quickly, steadily onward—'swims into his ken,' as the poet has it. The watcher's hand seeks the side of the telescope till his finger finds a little button, over which it poises itself to strike. On comes the star, 'without haste, without rest,' till it reaches one of the gleaming threads. Tap! The watcher's finger falls sharply on the button. Some three or four seconds later and the star has reached another 'wire,' as the spider-threads are commonly called. Tap! Again the button is struck. Another brief interval and the third wire is reached, and so on, until ten wires have been passed, and the transit is over. The intervals are not, however, all the same, the ten wires being grouped into three sets, two of three apiece, and the third of four.