Tag Archives: Harrison

The Gdansk Time-Ball

Photography by Carlos Dorce

Photography by Carlos Dorce

After the prize of 20.000 pounds established by the British Parliament in 1714 for someone who would find an exact method of measuring the geographical longitude of a ship on the open sea and the victory of John Harrison’s “chronometers”, the navigation across the oceans changed a lot. However, since even the most exact chronometers erred a few seconds after a long journey, a lot of sea ports decided to have a time-ball (as we saw in Greenwich!) installed on a tower or a lighthouse.

The ball’s fall at noon let the captains adjust their ship’s chronometers before the next voyage.

The Gdansk ball was the first one in the Baltic Sea and it seems to be the only openwork time-ball in the World. It was first constructed in 1876 on the top of a wooden tower which was especially built although it was transferred to the new Nowy Port lighthouse in 1894 (the current location!).

The invention ofradio by Marconi at the turn of the XIX-XX centuries spelled the end of the time-ball era. The first radio station in Gdansk went into service in 1921, and when in 1929 a heavy strom ripped the Gdansk time-ball off the top of the lighthouse, it was never repaired. First in 2008, four years after the lighthouse itself was restored and opened to the public, was the famous Time-Ball reconstructed.

Photography by Carlos Dorce

Photography by Carlos Dorce

I think I’m going to look for other time-balls in the World. It seems to be very interesting!

Location: The Gdansk Time-Ball in Nowy Port (map)

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The Royal Observatory in Greenwich (and III)

Source: Wikimedia Commons

The third step in the visit to the Royal Observatory of Greenwich is Flamsteed House.

The Royal Observatory of Greenwich was founded in 1675 when Charles II ordered that a small observatory be built in Greenwich Park and appointed John Flamsteed as his ‘astronomical observator’. Flamsteed’s task was to make observations that would improve astronomical navigation, in particular providing a means of finding longitude at sea.

Photography by Carlos Dorce

Photography by Carlos Dorce

The ceiling of the first room is painted with a map of the night sky and there are portraits of the ten Astronomers Royal who lived here between 1676 and 1948:

Photography by Carlos Dorce

Photography by Carlos Dorce

Christopher Wren was responsible for building the Observatory. He later said that it was designed ‘for the Observator’s habitation & a little for Pompe’. The following four rooms were Flamsteed’s living quarters. They were incorporated into the enlarged home of the Astronomer’s Royal over the next two and a half centuries. Beyond these, upstairs, is the magnificient Great Star Room, or Octagon Room.

ROG14

The Octagon Room by Francis Place (c. 1760)

The Octagon Room is one of the few surviving interiors designed by Wren and it was used mainly for observing eclipses, comets and other unusual celestial events.

The 32-inch Astronomical Quadrant is located in this room. It is signed by John Bird but the telescope which was once attached is missing.

Photography by Carlos Dorce

Photography by Carlos Dorce

The engraving of the Octagon Room by Francis Place shows a similar, earlier quadrant standing on a wheel-tripod platform, which allowed the astronomer to roll it from window to window.

On the wall behind the quadrant we can see three replicas of the clocks which were made in 1676 by Thomas Tompion and sold by Flamsteed’s widow some years later. There is also a replica telescope tube of the kind used here until 1765. Will my daughter be able to discover a new planet?

Photography by Carlos Dorce

Photography by Carlos Dorce

If we go downstairs now we’ll discover an exhibition about the determination of the longitude at sea:

Where am I?

At sea, navigation is a matter of life and death. Out of sight of land, how can you tell where you are?

By 1700, skilled seamen could find their position north or south (their latitude), but still lacked accurated instruments or methods to calculate their east-west position, known as longitude.

With growing international trade, the lives and valuable cargoes lost in shipwrecks made solving this ‘Longitude Problem’ urgent for all sea-going nations.

Photography by Carlos Dorce

Photography by Carlos Dorce

The exhibition starts with these two 17th-century globes from North Africa (left) and Persia (right) and then you meet the star of the ‘Longitude Problem’:

John Harrison Photography by Carlos Dorce

John Harrison (1693-1776) by Thomas King (c. 1766)
Photography by Carlos Dorce

Finding longitude – the timekeeper method

One solution to the Longitude Problem was an accurate and portable sea-going clock. By 1726, news of the Longitude Prize had reached John Harrison, a carpenter and self-taught clockmaker from Lincolnshire. Harrison was already making highly accurate land-based clocks and had solved major problems to do with temperature change and friction.

Harrison spent the next 45 years of his life developing portable sea-going timekeepers that would accurately, in spite of a ship’s motion and temperature changes. Each timekeeper represented years of obsessive labour.

By 1760, Harrison had solved the Longitude Problem with his fourth marine timekeeper, now known as H4. It is one of the most important machines ever made.

Photography by Carlos Dorce

Photography by Carlos Dorce

Harrison’s first timekeeper [H1]

This timekeeper took five years to build. In 1736, it was tested on a sea voyage to Lisbon and back. Harrison was very seasick, but the timekeeper worked. It was the most accurate sea-going clock then known, though not quite accurate enough to win the 20.000 pounds prize.

This prize was offered in 1734 by the British government for a ‘practical and useful’ method enabling ships to determine their longitude at sea.

In the exhibition there are also some timekeepers more and the portraits of some of the most important scientific men which lived in the same time as Harrison: Halley succeeded Flamsteed as Astronomer Royale and his major programme was to replace all the astronomical instruments which were sold by Flamsteed’s widow, and to chart the Moon’s 19-year cycle.

Edmund Halley Photography by Carlos Dorce

Edmund Halley by George White after G.Kneller (c.1721)
Photography by Carlos Dorce

Newton advised the Parliamentary committee that established the Longitude Prize and became a member of the Board of Longitude:

Sir Isaac Newton Photography by Carlos Dorce

Sir Isaac Newton by Jacobus Houbraken after G.Kneller (18th century)
Photography by Carlos Dorce

Finally, apart of the camera obscura, we can find outside the Family Tombstone of Halley which was moved to the Observatory from the churchyard of St. Margaret’s in Lee when Halley’s tomb was restored in 1854. The tomb itself is still located at St. Margaret’s with a replica tombstone in place:

Photography by Carlos Dorce

Photography by Carlos Dorce

As you have seen, you must visit the Royal Observatory in Greenwich if you visit London: it’s only a few metro stops from the center of the city!

LocationGreenwich Observatory (map)