A Visit To The Royal Observatory: Where Time Begins

The Royal Observatory sits proudly atop the hill in Greenwich Park, overlooking the spectacular Old Royal Naval College and, beyond that, the mighty River Thames, meandering its way around the Isle of Dogs. It may not be a particularly large or grand building, although its architecture is very elegant, but in terms of British and even world history, it is one of the most important buildings in London. 

I paid The Royal Observatory a visit and in this blog post I will cover its story, from its 17th century founding, its pivotal role in the advancement of maritime navigation and timekeeping, as well as showing you what you can see there today.

The Founding Of The Royal Observatory

The Royal Observatory was founded in 1675 by King Charles II, making it Britain’s first state-sponsored scientific institution.

Charles II was deeply interested in science, but the founding of The Royal Observatory was part of a bid to solve one very specific problem: how to determine longitude at sea.

Seaborne trade and exploration was crucial to European nations in the 17th century, for empire-building and commerce. Determining latitude (North-South position) aboard a ship was relatively easy, because it could be determined by measuring the angle of fixed stars such as Polaris (the North Star) above the horizon. Longitude however (East-West) was far more complicated.

The Longitude Problem

Where latitude has fixed celestial markers with predictable positions relative to the horizon, longitude is trickier because the sun and stars move with the Earth’s rotation on its axis. This made navigation at sea complicated and highly dangerous.

The Sun reaches its highest point at local midday, but that occurs at different times depending on your position East or West. Longitude could therefore be determined if you could compare your time with whatever time it was from a fixed other point or ‘meridian’. The Earth rotates 360 degrees every day and there are 24 hours in a day, so every hour difference denotes 15 degrees of difference in longitudinal position. Therefore if you were in a ship and it was midday but it was 5pm (PM meaning ‘post-meridian’) in London, you would know you were 75 degrees of longitude West. 75 degrees West of London would be roughly on the longitude of New York City. 

The challenge though, of course, was knowing what time it was at that fixed point, when you could not go on the internet or speak to someone in real time over the telephone. 

Two Competing Solutions

Two methods of determining longitude were proposed: the astronomical method and the time method. Charles II appointed John Flamsteed as the first Astronomer Royal to compile the most accurate star tables and lunar charts ever created from The Royal Observatory.

Flamsteed and his successors, Edmund Halley (of comet fame), James Bradley and many more spent decades meticulously mapping and recording the movements of stars and the moon. The hope was that these charts could be used by maritime avigators to determine longitude, particularly by comparing the movement of the moon relative to certain stars. 

The other proposed method of working out longitude was to create an accurate, portable sea-going timekeeper that could effectively carry the time of the starting point, or meridian, with the ship. We will come to back to this further down.

Why Greenwich?

The reason Greenwich was chosen as the location of The Royal Observatory was partly because of the elevated position on the hill, but mostly because it was royal land, therefore would cost nothing and permission did not need to be sought. Greenwich Palace has its origins back in the 15th century and was a favourite of King Henry VIII. Today it is the site of the Old Royal Naval College, which I have written about before here. The Queen’s House is also a fascinating visit. The other main reason was because it was close to the scientific community in London.

The building you can see today is known as Flamsteed House and was designed by Sir Christopher Wren, likely with the help of Robert Hooke.

It was designed as the home of the Astronomer Royal, but also purpose-built for astronomical observations. The Octagon Room for example is an eight-sided chamber built above the residential rooms and offered a wide view of the sky and space for advanced instruments.

It was also though designed for a bit of ‘pomp’, a space for visitors to do some amateur observations in elegant surroundings. It housed two clocks, the 13 foot long pendulums hidden behind the paneling to keep accurate time. These clocks proved that the Earth turns at a constant rate throughout the year. 

The original building had extra rooms then added to it in the 18th and 19th centuries. 

A prize

The Longitude Act of 1714 established the Board of Longitude and offered a financial prize of £20,000 to anyone who could solve the longitude problem. 

In 1767 the Astronomer Royal Nevil Maskelyne began publishing The Nautical Almanac, essentially the product of the decades of astronomical observations from Greenwich. This astronomical data, although very complicated, could be used by navigators with the right equipment and knowledge to try and determine longitude at sea. 

A Clockmaker From Yorkshire

The timekeeper method, as mentioned above, was the other proposed solution. Up until the mid 18th century however, a clock that worked to counterbalance the swing and sway of ships and could keep time accurately during the harsh, salty conditions at sea had never been created.

By 1726 the news of the longitude prize had reached a clockmaker and carpenter from West Yorkshire called John Harrison. Harrison is, I would argue, one of the great, relatively unsung, pioneers of British history.

Harrison spent the next 45 years of his life developing sea clocks (chronometers).

They have the four clocks he designed (H1, H2, H3 and H4) at The Royal Observatory to see. Each one was more brilliant and revolutionary than the last. H4 particularly, for which Harrison eventually won the prize, is really one of the most important scientific instruments in world history. It is a beautiful item for one but also, through significantly improving navigation, changed world history.

The Four Clocks

There is so much more to the amazing story of Harrison and the creation of his clocks. I would highly recommend reading the short, but fascinating, book by Dava Sobel called Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time. 

Greenwich Mean Time

In the 19th century the industrial and particularly railway revolution meant that accurate and standardised time across the country became even more important. 

In 1833 the red time ball was fitted at The Royal Observatory.

This red ball dropped and still does today at 1pm on the dot. This could then be observed by navigators aboard ships on the river and compared to their own chronometers on board. 

In 1880 Greenwich Mean Time was adopted as Britain’s standardised time.

The Prime Meridian

In 1884 the International Meridian Conference was held in Washington DC between 25 nations to agree on where the global Prime Meridian should be. Up until this point countries had generally used their own varied reference points/meridians.

The Greenwich meridian was chosed as the global Prime Meridian. This was predominantly because 70% of the world’s shipping at this time used the charts produced from observations from The Royal Observatory. Those charts naturally used Greenwich as their meridian.

Astronomers Royal at the Royal Observatory had used a few ever so slightly different meridians over the centuries, but the line used today was finally cemented in 1851 by Astronomer Royal Sir George Biddell Airy. His ‘transit circle’ telescope at The Royal Observatory pinpointed the precise longitude. 

It is worth adding that the GPS based International Reference Meridian today is actually located just over 100 metres East of the original line. This is because of the uneven density of the Earth, which Victorian astronomers could not account for. 

19th Century To Today 

Over the course of the 19th century, newer, larger and more powerful telescopes were installed at The Royal Observatory. Below, for example, is the Great Equatorial Telescope installed in 1893. 

Research staff numbers increased, such as the addition of five ‘Lady computers’ , as they were known, from 1890-1895 to take observations and photographs: Isabella Clemes, Alice Everett, Harriet Furniss, Edith Rix and Annie Russell.

Due to urban development and light pollution, the skies in Greenwich became unsuitable for astronomical observations and in 1948 the National observatory facilities were moved to Herstmonceux Castle in East Sussex. 

The buildings were then incorporated into the National Maritime Museum. It opened as a museum in 1960 and has educated and delighted visitors ever since.

Visiting The Royal Observatory 

The Royal Observatory is open 10am-5pm everyday. The exhibits are interesting, but to get the most out of a visit I would highly recommend listening to the free regular talks that they put on throughout the day. This is where, I think, you can get a much better understanding of the building’s history and significance. 

The cost for an adult ticket is £24 but there are also various concessions. 

Find out more about visiting here. 

Thank you for reading, more of London’s top historical spots below…