represents the “prime meridian,” our planet’s agreed line of zero longitude. It’s a steel strip across one of the paths surrounding the famous old observatory at Greenwich.
King Charles II founded his Royal Observatory in 1675. The idea had come, the year before, from Jonas Moore, chief of the Ordnance (artillery) Office; and Christopher Wren, architect of this and many other London buildings, chose the site. It is at the crest of a surprisingly steep slope looking north toward the Thames.
The red ball drops at 1 PM so that ships on the river can set their clocks to Greenwich Time. To the left of my bicycle are the 24-hour clock and the standard Imperial Yard and other measures; behind is the path leading to the prime meridian marker. Someone is emerging from the steeper path. Beyond the lower park is the National Maritime Museum; beyond the river are office towers of the modern business district called Canary Wharf.
The king appointed John Flamsteed as first Astronomer Royal. Astronomy merited royal support because of its seniority among the leaping sciences of the seventeenth century (Galileo, Kepler, Newton, Halley, Huygens – and Robert Hooke, who probably helped Wren design the observatory), but even more vitally for the hope it offered “to find out the so much desired longitude of places for the perfecting of the art of navigation.”
If you read Dava Sobel’s 1995 best-seller Longitude (full title Longitude, the true story of a lone genius who solved the greatest scientific mystery of his time), you’ll vividly remember how ships lost their way and collided with capes, because they did not know how far west they were. Latitude is easy to find from the stars, but longitude is far more difficult. The established astronomers believed the solution would come from measurements and calculations of the Moon; the “lone genius” (John Harrison) found it by building a sea-worthy clock.
The world agreed to base its systems of longitude and time on this observatory, and the observatory worked for over two centuries to carry out its other mandated tasks, “the rectifying of the tables of the motions of the heavens, and the places of the fixed stars.” But its operations had to be moved in 1948 to Herstmonceux Castle in Sussex,
and then in 1990 to Cambridge, leaving the Old Royal Observatory as a museum.
Actually the Herstmonceux move had been germinating since 1924 and took from 1948 to 1957. It was – hard for me to believe at this moment – even more of a struggle than our move from Lyme Regis to Greenwich, which took us and five good-natured Polish movers from early in the morning to late in the night of April 16. I spare you more about that strenuous day, except that it was a lovely spring day and I spent the middle of it riding in the truck beside driver Pyotr. His GPS system to my surprise started by taking us along Dorset lanes that I had not seen since exploring them many months before and may never see again; and then (about half way between Lyme and London) close past Stonehengethough in the opposite direction to this sketch from Astronomical Calendar 2003.