A Travellerspoint blog

Day 4 - Greenwich

Walking Tour and Royal Observatory

sunny 90 °F

The morning was a walking tour in Greenwich with the ship departing at 2 PM.

Below is a picture of St. Elfridge's Church. He was a monk in Canterbury who was kidnapped by Danes in the ninth century and taken to Greenwich. The church marks the site where he was martyred. Henry VIII was baptized in this church.

Greenwich Palace was the home base for the Tudor's, Henry VIII's family. The Queens house was built for one of the Tudor queens who did not want to live in the palace. Unfortunately, she died before she could move in.

All of these sites are located in the Greenwich Royal Park on land owned by the Royal Family. The equestrian events for the London Olympics were held here.

We left the tour midway to take in the Royal Observatory. Much of the development work on clocks, astrolabes, and sextants took place here. While others (Dutch or Portuguese) developed navigational systems for latitude (north-south position), it was the English that developed a system for determining longitude (east-west position). And the system was dependent on accurate timekeeping. A ship carried two clocks with the time set to Greenwich Mean Time. Then they noted the time when the sun reached its peak (local noon). The longitude could be calculated by the difference from Greenwich Mean Time as shown on their ship's clocks. This told them the degrees east or west of the prime meridian in Greenwich. Voyages sometimes lasted years, so the clocks had to be accurate for long periods. However, the clocks at that time used pendulum movements, which were not stable on a rolling ship. This drove the development of portable clocks with mechanical movements.

In one picture you will see me looking up at a red ball on top of the building. The observatory measured the suns position and dropped the ball when the sun reached its peak. All the ships in the Thames below would then adjust their clocks to noon.

The observatory also housed a succession of telescopes, including the largest of their time. These were used to study the movements of the stars as a basis for navigation.

The trip down the Thames was very interesting, and it lasted for three hours or more. We had to leave exactly at high tide in order clear the Tidal Barrier partway down the Thames. This series of barriers can be rotated to restrict the flow of water up the Thames to prevent flooding caused by king tides or wind.

Cutty Sark

Cutty Sark

St. Elfridge's Church

St. Elfridge's Church

Jerry in Front of Royal Observatory

Jerry in Front of Royal Observatory

Judy Straddling the Prime Meridien

Judy Straddling the Prime Meridien

View of Greenwich Park, Queen's House, and Greenwich Palace from Royal Observatory

View of Greenwich Park, Queen's House, and Greenwich Palace from Royal Observatory

Greenwich Palace (Home of the Tudors)

Greenwich Palace (Home of the Tudors)

Posted by longjerr 15:36 Archived in England

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