Flamsteed House and the Time Ball
Christopher Wren, with Robert Hooke (Wren 1632 to 1723) · 1675 to 1676; time ball added 1833
The red brick house with the twin turrets is the original Royal Observatory, built in sixteen seventy five for King Charles the Second so that his first Astronomer Royal, John Flamsteed, could map the stars accurately enough for sailors to find their way. Christopher Wren, himself a former professor of astronomy, designed it, and he later admitted that it was built a little for pomp. Money was so short that the bricks came from a demolished fort at Tilbury and the wood from an old gatehouse at the Tower of London.
Go inside and climb to the Octagon Room, the finest surviving Wren interior in Greenwich. Its tall windows were made for long telescopes, and the two year-going clocks by Thomas Tompion, with pendulums four metres long hidden in the wall, once let Flamsteed test whether the earth turned at a constant rate. Below are the modest rooms where the Astronomers Royal and their families lived until the observatory left Greenwich after the Second World War. On the roof, watch the bright red ball on its mast. Every day at five minutes to one it rises halfway, at two minutes to one it climbs to the top, and at one o'clock precisely it drops.
The time ball was installed in eighteen thirty three, the first public time signal in the world, so that ships on the river could set their chronometers by sight before sailing. It still falls each day. Flamsteed himself was a difficult and brilliant man who spent decades on his star catalogue and fought bitterly with Isaac Newton and Edmond Halley over its early publication. His observatory, built on the site of a medieval tower, became the reference point for the whole world.
Did You Know? The time ball drops at one o'clock rather than noon because at midday the astronomers were busy measuring the sun.
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