Monday morning started with Yuki going to school and Rob and I heading off to Greenwich to visit the Royal Observatory.

We travelled by tube, train and Docklands Light Rail to Greenwich. After walking a ways, we flagged down a cab and had it drive us up the rather large hill that the Observatory sits on.

In 1674, King Charles II appointed John Flamsteed as the first Astronomer Royal. His task was to find a way to determine longitude using the stars. Calculating latitude using the sun and stars was relatively straightforward, but at the time, no one had figured out how to measure longitude.

The foundation stone was laid at 3:14pm on the 10th of August, 1675 and construction was completed by Christmas that year. Flamsteed and two servants moved into Flamsteed House on the 10th of July 1676.

Over the years, successive Astronomers Royal established their own “prime meridians” which ran through their telescopes. The line established by Airy was recognized as the Prime Meridian of the World in 1884. (Trivia fact: The British Ordnance Survey maps still use Bradley’s Meridian as Longitude 0, not the Prime Meridian.)

Anyways, we took the standard tourist photos of each of us straddling the Prime Meridian and then watched the other tourists doing the same thing. There was a machine with a highly accurate clock in it which would give you a certificate saying when you visited the Prime Meridian for a pound. Mine says I paid it a pound coin at 11:01:3805 on 30 June 2003.

We toured the various buildings, looked at an awful lot of highly accurate clocks and then headed outside just before 13:00. Every day since 1833, a ball on top of Flamsteed House has been raised halfway up the mast at 12:55, to the top at 12:58 and then it drops at exactly 13:00. This was started so that the ships in the harbour could set their chronometers.

We watched with bated breath as the ball rose first to half mast and then all the way to the top. Two minutes later it dropped and it was 1:00pm. After a few more pictures, we headed down the hill and had something to eat at the National Maritime Museum before heading down to the dock to catch a tourboat back downtown.

The tour was quite interesting, but the drizzle, which had been occuring on and off most of the day so far, was back. The Thames is quite a polluted river. On our trip upstream saw us pass all sorts of flotsam heading out to sea.

Upon arrival at the dock next to Embankment station, we headed via the Underground to Tooting Broadway to do some grovery shopping and then returned home.

Click here to view the pictures from Day 4.