London and Greenwich Mean Time

Most of us likely only think of Greenwich as the location from which the time everywhere else is measured. So a visit to the Royal Observatory is essential. But there are a few other interesting reasons for visiting, making it a good trek for a lovely day. And surprisingly enough, we got a gorgeous day.

To get there we took the underground to catch an Uber boat to Greenwich. Upon arrival the most obvious feature is the Cutty Sark.

Cutty Sark Clipper Ship

Its sails measure 32,000 square feet in total. There are 11 miles of rigging altogether. The main mast is 153 feet high. The hull was sheathed in a copper and zinc alloy. This was to prevent things like barnacles and mollusks from burrowing into the ship.

Cutty Sark was built exclusively for the China tea trade. Tea had been enjoyed in Asia for centuries, but it did not reach Britain until the 1650s. It was also huge business, with over 30 ton imported in 1869 alone.

The drive to be the first to have the new tea fostered intense competition, hence the Cutty Sark was designed to be fast. But the opening of the Suez Canal meant that steamships could dominate the tea trade, which was previously handled by clippers. The Cutty Sark found greater success in the 1880s as a wool runner. In 1895, the Cutty Sark was sold to a Portuguese company and renamed the Ferreira. In 1954, the Cutty Sark was towed to Greenwich and restored, opening to the public in June 1957. 

Across the Thames is "The O2" Arena, aka "The O2". It is a multi-purpose arena (events, shopping and dining). The arena was built under the Millennium Dome that was constructed originally to house an exhibition celebrating the turn of the third millennium. 

Old Royal Navel Academy

Founded as the Royal Hospital for Royal Navy Pensioners (1604-1869...) it provided luxurious accommodations "to reflect the wealth and power of Britain". Formerly the site of a royal palace, the facility was designed by Christopher Wren. Noted for it architectural beauty and for it's spectacular Painted Hall. The stunning ceiling and wall decorations of the Painted Hall were conceived and executed by British artist Sir James Thornhill. The epic painting scheme, known as ‘Britain’s Sistine Chapel’ took nineteen years to its completion in 1726.The Hall was originally intended as a dining room for the Naval Pensioners but, due to its beauty, it soon transitioned to a ceremonial hall.

The last Greenwich Pensioners left the site in 1869 when it became home to the Royal Naval College, an officers’ training academy. From 1937 to 1997 the Painted Hall functioned as a dining space for trainee officers of the Royal Navy. The full complex is now home to the main campus of the University of Greenwich.

We stopped at Ye Olde Rose & Crown pub for a quick bite before touring the Observatory.

Royal Observatory, 

Since the late 19th century, the Royal Observatory is the historic source of the Prime Meridian of the world, Longitude 0° 0' 0''. It marks the divide between the eastern and western hemispheres.

The Harrison clocks

The Harrison clocks were designed to keep accurate time relative to the prime meridian (longitude 0° 0' 0''), thus keeping track of longitude while at sea.

John Harrison designed 4 clocks, each being more accurate than the previous ones. The clocks compensate for changes in temperature and, thanks to extensive anti-friction devices, run without any lubrication. He unveiled H-1 in 1735. In 1761 he developed the H-4, a much smaller portable round "watch" with a diameter of only 13 cm. Below areeamples of H-1, H-2, and H-3.

Prime Meridian 

The Prime Meridian is key but there are other Meridians in Greenwich. All of which are close to one another. 

• The Prime Meridian is the standard for longitude. 
• The UTC (Coordinated Universal Time) meridian, agreed upon in 1960, is based on the Airy meridian established in 1884. It is the standard for time. From what I can tell, the acronym UTC was chosen before the name Coordinated Universal Time was agreed on.
• The Bradley Meridian established in 1750 is still the reference point for Ordnance Survey maps today.

We homed in on the Prime Meridian for our photos, standing with one foot in the Western Hemisphere and one foot in the Eastern Hemisphere. Pat also noticed a cool 24 hour clock and Bill caught her taking its photo.

And finally you might think your phone is inaccurate in it's longitude measurement. Instead of longitude 0° 0' 0'' it will show you being at longitude 0° 0' 05".  This results from the coordinate system used for satellite navigation in phones and other devices taking into account later data on the Earth's slightly irregular shape.