In 1716 the Astronomer Royal of England bought up three hundred copies of his own book and burned them in a bonfire, which he described afterwards as a sacrifice to heavenly truth. The book had been printed without his consent, edited by a rival, and released while he was still working on it. He was sixty nine and had been measuring the same sky for forty years.
The quarrel between John Flamsteed, Edmond Halley and Isaac Newton is usually told as a piece of academic bad temper. It is more useful as a case study in a question that has never been settled: who owns a set of measurements, the person who made them or the science that needs them.
A Salary, a House, and No Instruments
Charles II founded the Royal Observatory at Greenwich in 1675 for a practical reason. Ships could find their latitude and could not find their longitude, and the leading proposal was the lunar distance method, which required knowing the position of the Moon against the stars to an accuracy nobody had.
Flamsteed was appointed the first Astronomer Royal at £100 a year, out of which he had to pay an assistant and his own tax. The warrant gave him a building and nothing to put in it. He supplied the instruments himself, and the best of them, a mural arc seven feet in radius, was paid for out of an inheritance from his father.
This detail decides most of what follows. The observations at Greenwich were made on private equipment by a man being paid a small stipend, and he considered them his property in a way that a modern salaried scientist could not.
He was also a very good observer. Using a telescopic sight and a micrometer where Hipparchus had used naked eye alignments and Tycho Brahe had used large graduated arcs, Flamsteed worked to an accuracy of a few seconds of arc, roughly ten times better than any catalogue before him. He recorded about twenty thousand observations by hand, and each one needed correction for refraction and reduction into a usable position, which is arithmetic he did himself, at night, in Greenwich, for four decades.
Newton Needs the Moon
Newton’s demand arrived in the 1690s. He was working on lunar theory for the second edition of the Principia, trying to show that the Moon’s complicated motion follows from universal gravitation, and the only data good enough to test it against were Flamsteed’s.
Flamsteed supplied observations, and then supplied more, and grew resentful at the way they were requested and at Newton’s reluctance to acknowledge where they came from. Newton, for his part, regarded a public servant sitting on unpublished data as an obstruction. Both positions are defensible. Neither man was capable of holding his temper while defending it.
The astronomer had already been drawn into the making of the Principia once before, since it was Halley who paid for the first edition and coaxed it out of Newton. Halley was, by temperament, the exact opposite of Flamsteed: quick, sociable, willing to publish an approximate result and improve it later.
Flamsteed had known Halley since they were young men, had helped him, and had come to detest him. He thought him irreligious, careless with other people’s work, and too fond of a public reputation. He would not print his catalogue until it was complete, and it was never complete, because every year of observation improved it.
The Book Printed Against Its Author
In 1704 Prince George of Denmark, the Queen’s husband, was persuaded to fund publication. Newton, by then President of the Royal Society, chaired the committee that supervised it. Flamsteed handed over the observational material for the first volume and kept back the catalogue itself, the part everyone actually wanted, on the grounds that it was unfinished.
Prince George died in 1708 and the project stalled. In 1711 Newton obtained a royal warrant making the Royal Society the official visitor of the Observatory, which gave him authority over Flamsteed’s work, and put Halley in charge of preparing the catalogue for the press.
Halley completed it from the material available, filled the gaps with his own estimates, and rewrote the preface. The Historia Coelestis appeared in 1712 in an edition of four hundred copies.
Flamsteed’s reaction was not simply wounded pride. He believed the printed catalogue was wrong in detail, that positions had been altered or interpolated without saying so, and that his name stood on a document he could not defend. A catalogue is a claim about where things are, and errors in it propagate silently into everything computed from it.
When the political weather changed in 1715 he got the Lord Chamberlain to hand over the three hundred unsold copies, and burned them.
What Each Man Left
Flamsteed died in 1719 with his own version unfinished. His widow Margaret and his former assistants Joseph Crosthwait and Abraham Sharp completed it, and the Historia Coelestis Britannica was published in three volumes in 1725, followed by the star atlas in 1729. It contains about three thousand stars, was the standard reference for a century, and the numbering system it produced is still in use: the designation 61 Cygni is a Flamsteed number.
Margaret also removed every instrument from the Observatory before the next Astronomer Royal arrived, on the correct legal ground that they had been bought with family money and were not the Crown’s.
The next Astronomer Royal, appointed in 1720, was Halley. He walked into an empty building at the age of sixty four, obtained a grant for a new transit instrument, and spent the following eighteen years on a single project: observing the Moon through a complete saros cycle of eighteen years and eleven days, the period after which eclipses very nearly repeat. He finished it at eighty two. It is the least flashy thing he ever did and possibly the most useful, and it is exactly the kind of patient accumulation he was accused of being incapable of.
Halley is remembered for the comet and for the eclipse map of 1715. Flamsteed is remembered, when he is remembered, as the difficult man who got in Newton’s way.
The Argument Underneath
Strip out the personalities and the dispute is about the status of data.
Flamsteed’s position was that an observation belongs to the observer, that publishing it prematurely puts a wrong number into circulation, and that once it is printed nobody can recall it. Newton’s position was that measurements paid for by the public exist to be used, that theory cannot advance while data sits in a drawer in Greenwich, and that a catalogue nine tenths finished is worth more to astronomy than a perfect one that never appears.
Both were right, which is why the argument recurs. It is the same disagreement that runs through every modern fight over embargoed datasets and delayed release, with the difference that the participants in 1712 had no institutional way to resolve it and used royal warrants and bonfires instead.
The Principia got its lunar theory, in a form Newton was never fully happy with. The Historia Coelestis Britannica got published, in the form its author intended, six years after his death. Both sides eventually won, and neither of them lived to enjoy it.
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