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I stood on a stainless steel strip running across the cobbled courtyard of a 17th century building. The excited, photo-clicking tourists all around were evidence that I wasn’t the only one interested in lines running across the face of the earth.

I thought back to that day in class V when I had spotted the Prime Meridian on a world map, running right through the middle of the earth, and wondered whether it was an actual line and how it would feel to stand on it. Was it even possible?

Years later, here I was. I doffed my hat to my 10-year-old self and grinned. Yes, the Prime Meridian was indeed a line, and it was possible to stand upon it.

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The first marine timekeeper, built by John Harrison Monty Fresco/Topical Press Agency/Getty Images
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The first marine timekeeper, built by John Harrison Monty Fresco/Topical Press Agency/Getty Images

As I entered the gates of the 183- acre Greenwich Park, a splash of green greeted me. Hailing from a country where any half-decent lawn has a “Keep off the grass" board, I was bewitched by the inviting expanse of grass. I wanted to follow the example of dozens of picnickers, flop down on it and watch the squirrels gambol in the trees above me. But I reminded myself of the time.

Across the park, on a little hill, sat the Royal Observatory where the Meridian was. I walked across, and made the short climb to the observatory gates. A large clock with a 24-hour analogue dial mounted on the wall outside the gate caught my eye. This turned out to be the Shepherd Gate Clock, the first clock to display Greenwich Mean Time (GMT) to the public in 1852.

The display board underneath gave me a little of its history. When the railway network started growing in England in the 19th century, local time across the country had to be coordinated. Charles Shepherd, a clockmaker, proposed a network of clocks whose times would be synchronized—Shepherd, incidentally, also supervised the construction of the telegraph network in India in 1853.

The clock that was now before me was one of many “Slave Clocks" operated by electric galvanic pulses transmitted from a master clock inside the observatory. The master clock also transmitted electric pulses by cables to a clock at London Bridge, from where the time was sent out to clocks in the rest of the country. By 1866, time signals were even being sent to Harvard University in the US, through transatlantic submarine cables.

It was thrilling to think of what a futuristic achievement this might have seemed at a time when cellphones and wireless technology were more than a century away.

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A 17th century illustration of an astronomer at work at Flamsteed House. Photo: Hulton Archive/Getty Images
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A 17th century illustration of an astronomer at work at Flamsteed House. Photo: Hulton Archive/Getty Images

Although latitudes could be determined easily by measuring the position of the sun, there was no reliable way to find out the longitude, so sea voyages were unnecessarily long and dangerous, and often ended in loss of vessels, lives and cargo. It was a particularly important issue given the mercantile and imperialistic stakes. So important, in fact, that a Board of Longitude was appointed in 1714 by the British Parliament, and rewards of thousands of pounds were offered to anyone who could find a solution.

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The rooms on the ground floor housed successive Astronomer Royals, like Edmond Halley, Nevil Maskelyne, John Pond and George Biddell Airy, and their families.

These rooms have been preserved as they were, with old fireplaces, grandfather clocks, candelabra on the walls, and carved wooden chairs. The sloping desks still have books, papers, scrolls and writing implements on them. There is minimal lighting here, and the only sound is of tourists walking on the wooden floorboards. I almost expected one of the astronomers, say, a wig-wearing Edmond Halley, the discoverer of Halley’s Comet, to enter the room in pointy shoes.

Yet another section of this building showcases the history of the longitude, and displays artefacts such as the iron and brass quadrants, sextants, and telescopes used by astronomers. Their books, notes, etc., are also on display.

Picnickers at Greenwich Park. Photo: Wikimedia Commons
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Picnickers at Greenwich Park. Photo: Wikimedia Commons

I gazed at the portraits of the Astronomers Royal and wondered how exactly they had solved the longitude problem.

A ship at sea could measure the local time using the position of the sun. If it then knew the time at a reference point, say at Greenwich, whose longitude was known, its sailors could find out the longitude they were on, because they knew that the earth turned 15 degrees of longitude every hour.

There wouldn’t have been any problem if there existed a reliable timekeeping machine that would show the time at a reference point, and which the ship could carry on board. But the chronometers available for ships didn’t work accurately owing to the pitching and rolling at sea.

Along came Tobias Mayer, a German astronomer, who prepared tables predicting the position of the moon with the help of the formulae and equations of Leonhard Euler. This was called the Lunar Method of calculating longitude. If you could determine the distance of the moon from a chosen celestial body, you could calculate the longitude at the place of observation.

The Board of Longitude admitted that this method worked, but the calculations were too complicated. The fifth Astronomer Royal, Nevil Maskelyne, came up with the idea of publishing an official Nautical Almanac every year, with pre-calculated lunar distances and the times at which they occur at Greenwich. In 1766, he published the first almanac for the year 1767, and subsequently, the observatory published almanacs every year until 1832, when the responsibility was transferred to Her Majesty’s Nautical Almanac Office.

This answered a question that I had had for a long time: Why was the Meridian at Greenwich chosen as the 0° longitude? Since Maskelyne was based there, he calculated the lunar distances and times with reference to Greenwich. And owing to the popularity of this almanac, the Greenwich Meridian became the common reference point for most seafaring countries.

So when the International Meridian Conference was held in Washington, DC, in 1884 to decide which meridian to set as the 0° longitude, it settled on Greenwich, since it would inconvenience the least number of people.

The Shepherd Gate Clock was the first clock to display Greenwich Mean Time to the public in 1852. Photo: Oli Scarff/Getty Images
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The Shepherd Gate Clock was the first clock to display Greenwich Mean Time to the public in 1852. Photo: Oli Scarff/Getty Images

Leaving the museum behind, I entered the piece de resistance of Flamsteed House—the Octagon Room. I caught my breath. With a 20ft-high roof, the room has 13ft-tall windows which were built specifically to observe eclipses, comets and the movement of planets. It has an intricate plaster ceiling, and wooden panelling on the walls—one of the few surviving interiors designed by Christopher Wren.

The Octagon Room was apparently good for watching the sky, but wasn’t well-suited for positional observations because none of the windows was in line with a meridian. So, without letting the king know about the shortcoming of this magnificent room, the astronomers made the important astronomical observations from a shed situated in the observatory gardens!

I spotted a room called “Transit Circle Room" and went to see what it was about. This room holds the Airy Transit Circle, an instrument used to determine the position of a star, and measure time by the exact moment when a particular star transits the central line from east to west in the sky.

This instrument was built by the seventh Astronomer Royal, George Biddell Airy. Its central line is the Greenwich Meridian— and when this was accepted as the Prime Meridian, it was also naturally agreed that the Universal Day would begin at midnight at this meridian. This was the origin of GMT. Airy’s Transit Circle was used to measure GMT from 1851-1927.

Immersed in the history of this place, I had almost forgotten my original reason for coming to Greenwich. I hurried out to the Meridian Courtyard. The Meridian is marked by a stainless steel strip. My heart doing a little jig, I stood on the line, straddling it with each leg in a different hemisphere, and mentally crossed this item off my bucket list.

Earlier, the line was marked by a brass strip. Since 2001, a green laser light pointed towards the city marks the longitude, and apparently, can be seen in the London night sky.

The Time Ball. Photo: Oli Scarff/Getty Images
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The Time Ball. Photo: Oli Scarff/Getty Images

As large as an exercise ball, the Time Ball was originally made of leather; now, it’s made of metal. Since it’s visible from the river, ships traditionally used this signal to check and set their time. Why 1pm? Why not noon? As I found out later, the astronomers were too busy with telescopic observations at noon to bother with the Time Ball. So they picked 1pm.

I walked to the only planetarium in London, the Peter Harrison Planetarium, set up in 2001, and housed inside a large tilted truncated bronze cone in the courtyard. The modern structure is popular with tourists, but looks slightly out of sync.

I went into a small dark room to see the Camera Obscura, which projected on the wall an inverted image of the view across Greenwich Park, using the pin-hole camera effect. Refreshed after a pastry, bun and coffee at the museum café, I walked out of the observatory gates and stood outside, gazing at the scene I had seen on the Camera Obscura.

As I watched the buildings of London sprawled before me, I imagined the scene at night, and understood why the scientific work of the observatory was moved to Herstmonceux Castle near East Sussex in the early 20th century—increasing light pollution in London. From 1960, the observatory has functioned just as a museum and tourist attraction.

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It reminded me that Greenwich was as much about the navy as it was about astronomy. I had seen the tea-clipper ship Cutty Sark outside Greenwich Park in the morning, and had hoped to see it too. But I had run out of time.

Next time, I thought, adding to my bucket list. As I hurried towards Greenwich station, intent on keeping up with the rest of my London itinerary, I laughed at the irony—I had no time, indeed in Greenwich, the home of time.

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