Thus, in his twenty-ninth year, John Flamsteed became the first Astronomer Royal. In many ways he was an ideal man for the post. In the twelve years which had passed since he left school he had accomplished an amazing amount of work. Despite his constant ill-health and severe sufferings, and the circumstance—which may be inferred from many expressions in his autobiographies—that he assisted his father in his business, he had made himself master, perhaps more thoroughly than any of his contemporaries, of the entire work of a practical astronomer as it was then understood. He was an indefatigable computer; the calculation of tables of the motions of the moon and planets, which should as faithfully as possible represent their observed positions, had had an especial attraction for him, and, as has been already mentioned, some years before his appointment he had drawn up a catalogue of stars, based upon the observations of Tycho Brahe. More than that, he had not been a merely theoretical worker, he had been a practical observer of very considerable skill, and, in the dearth of suitable instruments, had already made one or two for himself, and had contemplated the making of others. In his first letter to Sir Jonas Moore he asks for instruction as to the making of object-glasses for telescopes, for he was quite prepared to set about the task of making his own. In addition to his tireless industry, which neither illness nor suffering could abate, he was a man of singularly exact and business-like habits. The precision with which he preserves and records the dates of all letters received or sent is an illustration of this. On the other hand, he had the defects of his circumstances and character. His numerous autobiographical sketches betray him, not indeed as a conceited man, in the ordinary sense of the word, but as an exceedingly self-conscious one. Devout and high-principled he most assuredly was, but, on the other hand, he shows in almost every line he wrote that he was one who could not brook anything like criticism or opposition.

Such a man, however efficient, was little likely to be happy as the first incumbent of a new and important government post; but there was another circumstance which was destined to cause him greater unhappiness still.

If we believe, as surely we must, that not only the moral and the physical progress of mankind is watched over and controlled by God's good Providence, but its intellectual progress as well, then there can be no doubt that John Flamsteed was raised up at this particular time, not merely to found Greenwich Observatory, and to assist the solution of the problem of the longitude at sea, but also, and chiefly, to become the auxiliary to a far greater mind, the journeyman to a true master-builder. But for the founding of Greenwich Observatory, and for John Flamsteed's observations made therein, the working out of Newton's grand theory of gravitation must have been hindered, and its acceptance by the men of science of his time immensely delayed. We cannot regard as accidental the combination, so fortunate for us, of Newton, the great world-genius, to work out the problem, of Flamsteed, the painstaking observer, to supply him with the materials for his work, and of the newly-founded institution, Greenwich Observatory, where Flamsteed was able to gather those materials together. This is the true debt that we owe to Flamsteed, that, little as he understood the position in which he had been placed from the standpoint from which we see it to-day, yet, to the extent of his ability, and as far as he conceived it in accordance with his duty, he gave Newton such assistance as he could.

This is how we see the matter to-day. It wore a very different aspect in Flamsteed's eyes; and the two following documents, the one, the warrant founding the Observatory and making him Astronomer Royal; the other, the warrant granting him a salary, will go far to explain his position in the matter. He had a high-sounding, official position, which could not fail to impress him with a sense of importance; whilst his salary was so insufficient that he naturally regarded himself as absolute owner of his own work.

'Warrant for the Payment of Mr. Flamsteed's Salary.

'Charles Rex.

'Whereas, we have appointed our trusty and well-beloved John Flamsteed, Master of Arts, our astronomical observator, forthwith to apply himself with the most exact care and diligence to the rectifying the tables of the motions of the heavens, and the places of the fixed stars, so as to find out the so-much-desired longitude of places for the perfecting the art of navigation, Our will and pleasure is, and we do hereby require and authorize you, for the support and maintenance of the said John Flamsteed, of whose abilities in astronomy we have very good testimony, and are well satisfied, that from time to time you pay, or cause to be paid, unto him, the said John Flamsteed, or his assigns, the yearly salary or allowance of one hundred pounds per annum; the same to be charged and borne upon the quarter-books of the Office of the Ordnance, and paid to him quarterly, by even and equal portions, by the Treasurer of our said office, the first quarter to begin and be accompted from the feast of St. Michael the Archangel last past, and so to continue during our pleasure. And for so doing, this shall be as well unto you, as to the Auditors of the Exchequer, for allowing the same, and all other our officers and ministers whom it may concern, a full and sufficient warrant.

'Given at our Court at Whitehall, the 4th day of March, 1674-5.

'By his Majesty's Command,

'J. Williamson.

'To our right-trusty and well-beloved Counsellor, Sir Thomas Chichely, Knt., Master of our Ordnance, and to the Lieutenant-General of our Ordnance, and to the rest of the Officers of our Ordnance, now and for the time being, and to all and every of them.'

'Warrant for Building the Observatory.

'Charles Rex.

'Whereas, in order to the finding out of the longitude of places for perfecting navigation and astronomy, we have resolved to build a small observatory within our park at Greenwich, upon the highest ground, at or near the place where the Castle stood, with lodging-rooms for our astronomical observator and assistant, Our will and pleasure is, that according to such plot and design as shall be given you by our trusty and well-beloved Sir Christopher Wren, Knight, our surveyor-general of the place and scite of the said observatory, you cause the same to be fenced in, built and finished with all convenient speed, by such artificers and workmen as you shall appoint thereto, and that you give order unto our Treasurer of the Ordnance for the paying of such materials and workmen as shall be used and employed therein, out of such monies as shall come to your hands for old and decayed powder, which hath or shall be sold by our order of the 1st of January last, provided that the whole sum, so to be expended or paid, shall not exceed five hundred pounds; and our pleasure is, that all our officers and servants belonging to our said park be assisting to those that you shall appoint, for the doing thereof, and for so doing, this shall be to you, and to all others whom it may concern, a sufficient warrant.

'Given at our Court at Whitehall, the 22nd day of June, 1675, in the 27th year of our reign.

'By his Majesty's Command,

'J. Williamson.

'To our right-trusty and well-beloved Counsellor, Sir Thomas Chichely, Knt., Master-General of our Ordnance.'

The first question that arose, when it had been determined to found the new Observatory, was where it was to be placed. Hyde Park was suggested, and Sir Jonas Moore recommended Chelsea College, where he had already thought of establishing Flamsteed in a private observatory. Fortunately, both these localities were set aside in favour of one recommended by Sir Christopher Wren. There was a small building on the top of the hill in the Royal Park of Greenwich belonging to the Crown, and which was now of little or no use. Visible from the city, and easily accessible by that which was then the best and most convenient roadway, the river Thames, it was yet so completely out of town as to be entirely safe from the smoke of London. In Greenwich Park, too, but on the more easterly hill, Charles I. had contemplated setting up an observatory, but the pressure of events had prevented him carrying out his intention. A further practical advantage was that materials could be easily transported thither. The management of public affairs under Charles II. left much to be desired in the matter of efficiency and economy, and it was not very easy to procure what was wanted for the erection of a purely scientific building. However, the matter was arranged. A gate-house demolished in the Tower supplied wood; iron, and lead, and bricks were supplied from Tilbury Fort, and these could be easily brought by water to the selected site. The sum of £500, actually £520, was further allotted from the results of a sale of spoilt gunpowder; and with these limited resources Greenwich Observatory was built.

The foundation-stone was laid August 10, 1675, and Flamsteed amused himself by drawing the horoscope of the Observatory, a fact which—in spite of his having written across the face of the horoscope Risum teneatis amici? (Can you keep from laughter, my friends?), and his having two or three years before written very severely against the imposture of astrology—has led some modern astrologers to claim him as a believer in their cult. He actually entered into residence July 10, 1676.

His position was not a bright one. The Government had, indeed, provided him with a building for his observatory, and a small house for his own residence, but he had no instrument and no assistant. The first difficulty was partly overcome for the moment by gifts or loans from Sir Jonas Moore, and by one or two small loans from the Royal Society. The death of this great friend and patron, four years after the founding of the Observatory, and only three years after his entering into residence, deprived him of several of these; it was with difficulty that he maintained against Sir Jonas' heirs his claim to the instruments which Sir Jonas had given him. There was nothing for him to do but to make his instruments himself, and in 1683 he built a mural quadrant of fifty inches radius. His circumstances improved the following year, when Lord North gave him the living of Burstow, near Horley, Surrey, Flamsteed having received ordination almost at the time of his appointment to the Astronomer Royalship. We have little or no account of the way in which he fulfilled his duties as a clergyman. Evidently he considered that his position as Astronomer Royal had the first claim upon him. At the same time, comparatively early in life he had expressed his desire to fill the clerical office, and he was a man too conscientious to neglect any duty that lay upon him. That in spite of his feeble health he often journeyed to and fro between Burstow and Greenwich we know; and we may take it as certain that at a time when the standard of clerical efficiency was extremely low, he was not one of those who

His chief source of income, however, seems to have been the private pupils whom he took in mathematics and astronomy. These numbered in the years 1676 to 1709 no fewer than 140; and as many of them were of the very first and wealthiest families in the kingdom, the gain to Flamsteed in money and influence must have been considerable. But it was most distasteful work. It was in no sense that which he felt to be his duty, and which he had at heart. It was undertaken from sheer, hard necessity, and he grudged bitterly the time and strength which it diverted from his proper calling.

How faithfully he followed that, one single circumstance will show. In the thirteen years ending 1689, he made 20,000 observations, and had revised single-handed the whole of the theories and tables of the heavenly bodies then in use.

In 1688 the death of his father brought him a considerable accession of means, and, far more important, the assistance of Abraham Sharp,[1] the first and most distinguished of the long list of Greenwich assistants, men who, though far less well known than the Astronomers Royal, have contributed scarcely less in their own field to the high reputation of the Observatory.

Sharp was not only a most careful and indefatigable calculator, he was what was even more essential for Flamsteed—a most skilful instrument-maker; and he divided for him a new mural arc of 140° and seven feet radius, with which he commenced operations on December 12, 1689. Above all, Sharp became his faithful and devoted friend and adherent, and no doubt his sympathy strengthened Flamsteed to endure the trouble which was at hand.

That trouble began in 1694, when Newton visited the Royal Observatory. At that time Flamsteed, though he had done so much, had published nothing, and Newton, who had made his discovery of the laws of gravitation some few years before, was then employed in deducing from them a complete theory of the moon's motion. This work was one of absolutely first importance. In the first place and chiefly, upon the success with which it could be carried out, depended undoubtedly the acceptance of the greatest discovery which has yet been made in physical science. Secondarily—and this should, and no doubt did, appeal to Flamsteed—the perfecting of our knowledge of the movements of the moon was a primary part of the very work which he was commissioned to do as Astronomer Royal. Newton was, therefore, anxious beyond everything to receive the best possible observations of the moon's places, and he came to Flamsteed, as to the man from whom he had a right to expect to receive a supply of them. At first Flamsteed seems to have given these as fully as he was able; but it is evident that Newton chafed at the necessity for these frequent applications to Flamsteed, and to the constant need of putting pressure upon him. Flamsteed, on the other hand, as clearly evidently resented this continual demand. Feeling, as he keenly did, that, though he had been named Astronomer Royal, he had been left practically entirely without support; his instruments were entirely his own, either made or purchased by himself; his nominal salary of £100 was difficult to get, and did not nearly cover the actual current expenses of his position, he not unnaturally regarded his observations as his own exclusive property. He had a most natural dislike for his observations to be published, except after such reduction as he himself had carried through, and in the manner which he himself had chosen. The idea which was ever before him was that of carrying out a single great work that should not only be a monument to his own industry and skill, but should also raise the name of England amongst scientific nations. He complained of it, therefore, both as a personal wrong and an injury to the country when some observations of Cassini's were combined with some observations of his own in order to deduce a better orbit for a comet.

Unknown to himself, therefore, he was called upon to decide a question that has proved fundamental to the policy of Greenwich Observatory, and he decided it wrongly—the question of publication. Newton had urged upon him as early as 1691 that he should not wait until he had formed an exhaustive catalogue of all the brighter stars, but that he should publish at once a catalogue of a few, which might serve as standards; but Flamsteed would not hear of it. He failed to see that his office had been created for a definite practical purpose, not for the execution of some great scheme, however important to science. All his work of thirty years had done nothing to forward navigation so long as he published nothing. But if, year by year, he had published the places of the moon and of a few standard stars, he would have advanced the art immensely and yet have not hindered himself from eventually bringing out a great catalogue. No doubt the little incident of Newton's difficulty with the microscope, of which he had forgotten the object-glass, had given Flamsteed a low opinion of Newton's qualifications as a practical astronomer. If so, he was wrong, for Newton's insight into practical matters was greater than Flamsteed's own, and his practical skill was no less, though his absent-mindedness might occasionally lead him into an absurd mistake.

The following extract from Flamsteed's own 'brief History of the Observatory' gives an account of his view of Newton's action towards him in desiring the publication of his star catalogue, and at the same time it illustrates Flamsteed's touchy and suspicious nature.

'Whilst Mr. Flamsteed was busied in the laborious work of the catalogue of the fixed stars, and forced often to watch and labour by night, to fetch the materials for it from the heavens, that were to be employed by day, he often, on Sir Isaac Newton's instances, furnished him with observations of the moon's places, in order to carry on his correction of the lunar theory. A civil correspondence was carried on between them; only Mr. Flamsteed could not but take notice that as Sir Isaac was advanced in place, so he raised himself in his conversation and became more magisterial. At last, finding that Mr. Flamsteed had advanced far in his designed catalogue by the help of his country calculators, that he had made new lunar tables, and was daily advancing on the other planets, Sir Isaac Newton came to see him (Tuesday, April 11, 1704); and desiring, after dinner, to be shown in what forwardness his work was, had so much of the catalogue of the fixed stars laid before him as was then finished; together with the maps of the constellations, both those drawn by T. Weston and P. Van Somer, as also his collation of the observed places of Saturn and Jupiter, with the Rudolphine numbers. Having viewed them well, he told Mr. Flamsteed he would (i.e. he was desirous to) recommend them to the Prince privately. Mr. Flamsteed (who had long been sensible of his partiality, and heard how his two flatterers cried Sir Isaac's performances up, was sensible of the snare in the word privately) answered that would not do; and (upon Sir Isaac's demanding "why not?") that then the Prince's attendants would tell him these were but curiosities of no great use, and persuade him to save that expense, that there might be the more for them to beg of him: and that the recommendation must be made publicly, to prevent any such suggestions. Sir Isaac apprehended right, that he was understood, and his designs defeated: and so took his leave not well satisfied with the refusal.

'It was November following ere Mr. Flamsteed heard from him any more: when, considering with himself that what he had done was not well understood, he set himself to examine how many folio pages his work when printed would fill; and found upon an easy computation that they would at least take up 1400. Being amazed at this, he set himself to consider them more seriously; drew up an estimate of them; and, to obviate the misrepresentations of Dr. S[loane] and some others, who had given out that what he had was inconsiderable, he delivered a copy of the estimate to Mr. Hodgson, then lately chosen a member of the Royal Society, with directions to deliver it to a friend, who he knew would do him justice; and, on this fair account, obviate those unjust reports which had been studiously spread to his prejudice. It happened soon after, Mr. Hodgson being at a meeting, spied this person there, at the other side of the room; and therefore gave the paper to one that stood in some company betwixt them, to be handed to him. But the gentleman, mistaking his request, handed to the Secretary [Dr. Sloane], who, being a Physician, and not acquainted with astronomical terms, did not read it readily. Whereupon another in the company took it out of his hands; and, having read it distinctly, desired that the works therein mentioned might be recommended to the Prince; the charge of printing them being too great either for the author or the Royal Society. Sir Isaac closed in with this.'

The work was in consequence recommended to Prince George of Denmark, the Queen's Consort; but it was not till November 10, 1705, that the contract for the printing was signed. Two years later, the observations which he had made with his sextant in his first thirteen years of office were printed. Then came the difficulty of the catalogue. It was not complete to Flamsteed's satisfaction, and he was most unwilling to let it pass out of his hands. However, two manuscripts, comprising some three-quarters of the whole, were deposited with referees, the first of these being sealed up. The seal was broken with Flamsteed's concurrence; but the fact that it had been so broken was made by him the subject of bitter complaint later. At this critical juncture Prince George died, and a stop was put to the progress of the printing. Two years more elapsed without any advance being made, and then, in order to check any further obstruction, a committee of the Royal Society was appointed as a Board of Visitors to visit and inspect the Observatory, and so maintain a control over the Astronomer Royal. This was naturally felt by so sensitive a man as Flamsteed as a most intolerable wrong, and when he found that the printing of his catalogue had been placed in the hands of Halley as editor, a man for whom he had conceived the most violent distrust, he absolutely refused to furnish the Visitors with any further material. This led to, perhaps, the most painful scene in the lives either of Newton or Flamsteed. Flamsteed was summoned to meet the Council of the Royal Society at their rooms in Crane Court. A quorum was not present, and so the interview was not official, and no record of it is preserved in the archives. Flamsteed has himself described it with great particularity in more than one document, and it is only too easy to understand the scene that took place. Newton was a man who had an absolutely morbid dread of anything like controversy, and over and over again would have preferred to have buried his choicest researches, rather than to have encountered the smallest conflict of the kind. He was perhaps, therefore, the worst man to deal with a high-principled, sensitive, and obstinate man who was in the wrong, and yet who had been so hardly dealt with that it was most natural for him to think himself wholly in the right. Flamsteed adhered absolutely to his position, from which it is clear it would have been extremely difficult for the greatest tact and consideration to have dislodged him. Newton, on his part, simply exerted his authority, and, that failing, was reduced to the miserable extremity of calling names. The scene is described by Flamsteed himself, in a letter to Abraham Sharp, as follows:—

'I have had another contest with the President[2] of the Royal Society, who had formed a plot to make my instruments theirs; and sent for me to a Committee, where only himself and two physicians (Dr. Sloane, and another as little skilful as himself) were present. The President ran himself into a great heat, and very indecent passion. I had resolved aforehand his kn—sh talk should not move me; showed him that all the instruments in the Observatory were my own; the mural arch and voluble quadrant having been made at my own charge, the rest purchased with my own money, except the sextant and two clocks, which were given me by Sir Jonas Moore, with Mr. Towneley's micrometer, his gift, some years before I came to Greenwich. This nettled him; for he has got a letter from the Secretary of State for the Royal Society to be Visitors of the Observatory, and he said, "as good have no observatory as no instruments." I complained then of my catalogue being printed by Raymer, without my knowledge, and that I was robbed of the fruit of my labours. At this he fired, and called me all the ill names, puppy, etc., that he could think of. All I returned was, I put him in mind of his passion, desired him to govern it, and keep his temper: this made him rage worse, and he told me how much I had received from the Government in thirty-six years I had served. I asked what he had done for the £500 per annum that he had received ever since he had settled in London. This made him calmer; but finding him going to burst out again, I only told him my catalogue, half finished, was delivered into his hands, on his own request, sealed up. He could not deny it, but said Dr. Arbuthnott had procured the Queen's order for opening it. This, I am persuaded, was false; or it was got after it had been opened. I said nothing to him in return; but, with a little more spirit than I had hitherto showed, told them that God (who was seldom spoken of with due reverence in that meeting) had hitherto prospered all my labours, and I doubted not would do so to a happy conclusion; took my leave and left them. Dr. Sloane had said nothing all this while; the other Doctor told me I was proud, and insulted the President, and ran into the same passion with the President. At my going out, I called to Dr. Sloane, told him he had behaved himself civilly, and thanked him for it. I saw Raymer after, drank a dish of coffee with him, and told him, still calmly, of the villany of his conduct, and called it blockish. Since then they let me be quiet; but how long they will do so I know not, nor am I solicitous.'

The Visitors continued the printing, Halley being the editor, and the work appeared in 1712 under the title of Historia Cœlestis. This seemed to Flamsteed the greatest wrong of all. The work as it appeared seemed to him so full of errors, wilfully or accidentally inserted, as to be the greatest blot upon his fair fame, and he set himself, though now an old man, to work it out de novo and at his own expense. To that purpose he devoted the remaining seven years of his life. Few things can be more pathetic than the letters which he wrote in that period referring to it. He was subject to the attacks of one of the cruelest of all diseases—the stone; he was at all times liable to distracting headaches. He had been, from his boyhood, a great sufferer from rheumatism, and yet, in spite of all, he resolutely pushed on his self-appointed task. The following extract from one of his letters will give a more vivid idea of the brave old man than much description:—

'I can still, I praise God for it, walk from my door to the Blackheath gate and back, with a little resting at some benches I have caused to be set up betwixt them. But I found myself so tired with getting up the hill when I return from church, that at last I have bought a sedan, and am carried thither in state on Sunday mornings and back; I hope I may employ it in the afternoons, though I have not hitherto, by reason of the weather is too cold for me.'

After the death of Queen Anne, a change in the ministry enabled him to secure that three hundred copies of the total impression of four hundred of the Historia Cœlestis were handed over to him. These, except the first volume, containing his sextant observations (which had received his own approval), he burned, 'as a sacrifice to heavenly truth.' His own great work had advanced so far that the first volume was printed, and much of the second, when he himself died, on the last day of 1719. He was buried in the chancel of Burstow Church.

The completion of his work took ten years more; a work of piety and regard on the part of his assistant, Joseph Crosthwait.

When compared with the catalogues that have gone before, it was a work of wonderful accuracy. Nevertheless, as Caroline Herschel showed, nearly a century later, not a few errors had crept into it. Some of the stars are non-existent, others have been catalogued in more than one constellation; important stars have been altogether omitted. Perhaps the most serious fault arises from the neglect of Flamsteed to accept from Newton a practical hint, namely, to read the barometer and thermometer at the time of his observations. Nevertheless, the work accomplished was not only wonderful under the untoward conditions in which Flamsteed was placed; it was wonderful in itself, winning from Airy the following high encomium:—

'In regard not only to accuracy of observation, and to detail in publication of the methods of observing, but also to steadiness of system followed through many years, and to completeness of calculation of the useful results deduced from the observations, this work may shame any other collection of observations in this or any other country.'

This catalogue was not Flamsteed's only achievement. He had determined the latitude of the Observatory, the obliquity of the ecliptic, and the position of the equinoctial points. He thought out an original method of obtaining the absolute right ascensions of stars by differential observations of the places of the stars and the sun near to both equinoxes. He had revised and improved Horrox's theory of the lunar motions, which was by far the best existing in Flamsteed's day. He showed the existence of the long inequality of Jupiter and Saturn; that is to say, the periodic influence which they exercise upon each other. He determined the time in which the sun rotates on its axis, and the position of that axis. He observed an apparent movement of the stars in the course of a year, which he ascribed, though erroneously, to the stellar parallax, and which was explained by the third Astronomer Royal, Bradley.

Flamsteed not only met with harsh treatment during his lifetime; he has not yet received, except from a few, anything like the meed of appreciation which is his just due; but, at least, his successors in the office have not forgotten him. They have been proud that their official residence should be known as Flamsteed House, and his name is inscribed over the main entrance of the latest and finest of the Observatory buildings, and his bust looks forth from its front towards the home where he laboured so devotedly for nearly fifty years. But he has received little honour, save at Greenwich, and—in spite of the proverb—in his other home, the village of Burstow, in Surrey, of which he was for many years the rector. Here a stained glass window representing, appropriately, the Adoration of the Magi, has been recently set up to his memory, largely through the interest taken in his history by an amateur astronomer of the neighbourhood, Mr. W. Tebb, F.R.A.S.

No instrument of Flamsteed's remains in the Observatory, his wife removing them after his death. But we may consider his principal instrument, the mural quadrant made for him by Abraham Sharp, as represented by the remains of a quadrant by the same artist, which was presented to the Observatory by the Rev. N. S. Heineken, in 1865, and now hangs over the door of the transit room.

CHAPTER III

HALLEY AND HIS SUCCESSORS

There is no need to give the lives of the succeeding Astronomers Royal so fully as that of Flamsteed. Not that they were inferior men to him; on the contrary, there can be little doubt that we ought to reckon some of them as his superiors, but, in the case of several, their best work was done apart from Greenwich Observatory, and before they came to it.

This was particularly the case with Edmund Halley. Born on October 29, 1656, he was ten years the junior of Flamsteed. Like Flamsteed, he came of a Derbyshire family, though he was born at Haggerston, in the parish of St. Leonard's, Shoreditch. He was educated at St. Paul's School, where he made very rapid progress, and already showed the bent of his mind. He learnt to make dials; he made himself so thoroughly acquainted with the heavens that it is said, 'If a star were displaced in the globe he would presently find it out,' and he observed the changes in the direction of the mariner's compass. In 1673 he went to Queen's College, Oxford, where he observed a sunspot in July and August, 1676, and an occultation of Mars. This was not his first astronomical observation, as, in June, 1675, he had observed an eclipse of the moon from his father's house in Winchester Street.

Not long after his return from this tour, Halley was led to that undertaking for which we owe him the greatest debt of gratitude, and which must be regarded as his greatest achievement.

Some fifty years before, the great Kepler had brought out the third of his well-known laws of planetary motion. These laws stated that the planets move round the sun in ellipses, of which the sun occupies one of the foci; that the straight line joining any planet with the sun moves over equal areas of space in equal periods of time; and, lastly, that the squares of the times in which the several planets complete a revolution round the sun are proportional to the cubes of their mean distances from it. These three laws were deduced from actual examination of the movements of the planets. Kepler did not work out any underlying cause of which these three laws were the consequence.

But the desire to find such an underlying cause was keen amongst astronomers, and had given rise to many researches. Amongst those at work on the subject was Halley himself. He had seen, and been able to prove, that if the planets moved in circles round the sun, with the sun in the centre, then the law of the relation between the times of revolution and the distances of the planets would show that the attractive force of the sun varied inversely as the square of the distance. The actual case, however, of motion in an ellipse was too hard for him, and he could not deal with it. Halley therefore went up to Cambridge to consult Newton, and, to his wonder and delight, found that the latter had already completely solved the problem, and had proved that Kepler's three laws of planetary motion were summed up in one, namely, that the sun attracted the planets to it with a force inversely proportional to the square of the distance.

Halley was most enthusiastic over this great discovery, and he at once strongly urged Newton to publish it. Newton's unwillingness to do so was great, but at length Halley overcame his reluctance; and the Royal Society not being able at the time to afford the expense, Halley took the charges upon himself, although his own resources had been recently seriously damaged by the death of his father.

The publication of Newton's Principia, which, but for him, might never have seen the light, and most certainly would have been long delayed, is Halley's highest claim to our gratitude. But, apart from this, his record of scientific achievement is indeed a noble one. Always, from boyhood, he had taken a great interest in the behaviour of the magnetic compass, and he now followed up the study of its variations with the greatest energy. For this purpose it was necessary that he should travel, in view of the great importance of the subject to navigation. King William III. gave him a captain's commission in the Royal Navy—a curious and interesting illustration of the close connection between astronomy and the welfare of our navy—and placed him in command of a 'pink,' that is to say, a small vessel with pointed stern, named the Paramour, in which he proceeded to the southern ocean. His first voyage was unfortunate, but the Paramour was recommissioned in 1699, and he sailed in it as far as south latitude 52°.

In 1701 and the succeeding year he made further voyages in the Paramour, surveying the tides and coasts of the British Channel and of the Adriatic, and helping in the fortification of Trieste. He became Savilian Professor of Geometry at Oxford in 1703, having failed twelve years previously to secure the Savilian Professorship of Astronomy, mainly through the opposition of Flamsteed, who had already formed a strong prejudice against him, which some writers have traced to Halley's detection of several errors in one of Flamsteed's tide-tables, others to Halley's supposed materialistic views. Probably the difference was innate in the two men. There was likely to be but little sympathy between the strong, masterful man of action and society and the secluded, self-conscious, suffering invalid. At any rate, in the contest between Newton and Flamsteed, which has been already described, Halley took warmly the side of the former, and was appointed to edit the publication of Flamsteed's results, and, on the death of the latter, to succeed him at the Royal Observatory.

The condition of things at Greenwich when Halley succeeded to the post of Astronomer Royal in 1720 was most discouraging. The instruments there had all belonged to Flamsteed, and therefore, most naturally, had been removed by his widow. The Observatory had practically to be begun de novo, and Halley had now almost attained the age at which in the present day an Astronomer Royal would have to retire. More fortunate, however, than his predecessor, he was able to get a grant for instruments, and he equipped the Observatory as well as the resources of the time permitted, and his transit instrument and great eight-foot quadrant still hang upon the Observatory walls.

As Astronomer Royal his great work was the systematic observation of the positions of the moon through an entire saros. As is well known, a period of eighteen years and ten or eleven days brings the sun and moon very nearly into the same positions relatively to the earth which they occupied at the commencement of the period. This period was well known to the ancient Chaldeans, who gave it its name, since they had noticed that eclipses of the sun or eclipses of the moon recurred at intervals of the above length. It was Halley's desire to obtain such a set of observations of the moon through an entire saros period as to be able to deduce therefrom an improved set of tables of the moon's motion. It was an ambitious scheme for a man so much over sixty to undertake, nevertheless he carried it through successfully.

His desire to complete this scheme, and to found upon it improved lunar tables, hindered him from publishing his observations, for he feared that others might make use of them before he was in a position to complete his work himself. This omission to publish troubled Newton, who, as President of the Royal Society—the Greenwich Board of Visitors having lapsed at Queen Anne's death—drew attention at a meeting of the Royal Society, March 2, 1727, to Halley's disobedience of the order issued under Queen Anne, for the prompt communication of the Observatory results. That Newton should thus have put public pressure upon Halley, the man to whom he was so much indebted, and with whom there was so close an affection, is sufficient proof that his similar attitude towards Flamsteed was one of principle and not of arbitrariness. Halley, on his side, stood firm, as Flamsteed had done, urging the danger that, by publishing before he had completed his task, he might give an opportunity to others to forestall his results. It is said—probably without sufficient ground—that this refusal broke Newton's heart and caused his death. Certainly Halley's writings in that very year show his reverence and affection for Newton to have been as keen and lively as ever.

Halley's work at the Observatory went on smoothly, on the lines he had laid down for himself, for ten years after Newton's death; but in 1737 he had a stroke of paralysis, and his health, which had been remarkably robust up to that time, began to give way. He died January 14, 1742, and was buried in the cemetery of Lee Church.

As an astronomer, his services to the science rank higher than those of his predecessor; but as Astronomer Royal, as director, that is to say, of Greenwich Observatory, he by no means accomplished as much as Flamsteed had done. Professor Grant, in his History of Physical Astronomy, says that he seems to have undervalued those habits of minute attention which are indispensable to the attainment of a high degree of excellence in the practice of astronomical observation. He was far from being sufficiently careful as to the adjustment of his instruments, the going of his clocks, or the recording of his own observations. The important feature of his administration was that under him the Observatory was first supplied with instruments which belonged to it.