Flamsteed Astronomy Society

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In the end Flamsteed succeeded brilliantly in completing the first piece of the longitude puzzle.   But it took him the rest of his life.   He worked at Greenwich for over 40 years leaving only to visit Burstow at Christmas and in the summer to make sure the tithes (church taxes) were collected.   By the time of his death in 1719 he had completed around 30,000 observations.   Thanks to his obsessive perfectionism little had been published in his lifetime.  Only because of the determination of his widow Margaret, and the dedication of his old assistant Joseph Crosthwait, was his work published, first the catalogue Historia Coelestis Brittanica (the British Account of the Stars) in 1725 and then the Atlas Coelestis in 1729.  3000 star positions were now available with a precision sufficient to form a basis for practical navigation.   Flamsteed’s catalogue was the first of the northern skies compiled from telescope observations.  Previous catalogues, like Tycho’s, had been compiled from observations using open sights.

Much was left to be done to complete the lunar distance technique.   Despairing a solution from Greenwich, In 1714 the Government had offered the Longitude Prize.  £20,000 (around £3 millions in today’s values) was offered for a  ‘useful and practical’ technique to find longitude accurate to half a degree (about 30 miles) after a 5-week voyage to the West Indies.  Now everyone was interested in the problem and a piece of the £20,000.  A ‘theory of the Moon’ to enable lunar positions to be accurately predicted, was very slow to come however.   Halley, Flamsteed’s successor, worked at Greenwich for a whole 18-year Saros cycle of lunar position measurement.  In fact Halley coined the name ‘Saros’.  But Halley’s work in his later years lacked rigour.  The third Astronomer Royal, James Bradley, had taken up the baton and was beginning to bring new levels of precision to the problem when the answer appeared from Germany.   Prof. Tobias Mayer in Goettingen working with the latest lunar physics developed in France and elsewhere had compiled a set of tables which he sent to the Admiralty in London seeking an award from the Longitude Prize.  Bradley checked the tables against the Greenwich observations and found them excellent .  He gave them to a young astronomer, Nevil Maskelyne, who was off to St Helena in the south Atlantic to observe the Transit of Venus of 1761.  Maskelyne was clouded out on St. Helena, but returned a full convert to the lunar distance technique.  When he in turn became Astronomer Royal he was already publishing the tables which became the Nautical Almanac in 1767.  With a cheap copy of the Almanac and a recently-invented sextant, a good navigator could now find longitude, provided the Moon was visible, and assuming skill with the sextant on a bucking deck followed by 30 minutes of accurate calculation without the aid of a pocket-calculator, computer, or safety net.   But did the astronomers win the Longitude Prize?   They did not.   That honour fell to an upstart ‘mechanik’ from Lincolnshire who appeared in 1730 with his ingenious ideas for a marine timekeeper.  Another obsessive perfectionist who dedicated his life to this single objective.

The title ‘Astronomical Observator’ soon became known as Astronomer Royal.  Flamsteed was just the first in a long line of distinguished astronomers to hold the post.  The present holder Sir Martin Rees, is the fifteenth.  After the retirement of the eleventh Astronomer Royal, Sir Richard Woolley, the post became an honorary title.  Sir Richard was the last also to be Director of the Royal Observatory Greenwich (later RGO).  In the early 1950s the Observatory establishment moved from Greenwich to Herstmonceux, and in 1990 to Cambridge, only to be closed completely in 1998.  The original Greenwich site is now of course beautifully preserved as part of the National Maritime Museum

Read more at —

History of the Royal Observatory

Portraits of the Astronomers Royal

Flamsteed in the Painted Hall Greenwich

Flamsteed and Burstow


Book List —

John L. Birks - John Flamsteed.  The first Astronomer Royal at Greenwich (1999)

Derek Howse —

Greenwich Observatory 1675—1975

Greenwich Time and the Longitude (1980 bis)

Francis Place and the early history of the Greenwich Observatory (1975)

Emily Winterburn - The Astronomers Royal (2003)

Colin A. Ronan - Their Majesties’ Astronomers (1967)

The post of Astronomer Royal is 330 years old

John Flamsteed


Edmond Halley


James Bradley


Nathaniel Bliss


Nevil Maskelyne


John Pond


George Airy


William Christie


Frank Dyson


Harold Spencer Jones


Richard van der Riet Wooley


Martin Ryle


Francis Graham-Smith


Arnold Wolfendale


Martin Rees