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- [00:00]
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Narrator/Podcast Host Introduction
Why does the world set its watches by a small building in South East London? Founded by Charles II in 1675, the Royal Observatory at Greenwich gave gave its name to the system that has governed our time for more than three centuries and has also been pivotal in shaping the global standardisation of time. In this episode of the History Extra podcast, Dr. Emily Ackermans, curator of time at Royal Museums Greenwich, joined Eleanor Evans to introduce the site and explain more about its history.
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Eleanor Evans
Emily, thank you so much for joining me for this episode of the History Extra podcast. How are you doing today?
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Dr. Emily Ackerman
I'm doing very well, thank you.
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Eleanor Evans
It's lovely to have you here and I want to start with your role. You are Curator of Time at the Royal Museum's Gwenwich. Now, this title, I have to start by asking about it. What does this role encompass?
- [01:08]
Dr. Emily Ackerman
So this role is I look after our fantastic collection of timekeeping objects. So anything to do with time, basically, I get to research and talk about the many objects in our collection and many of these are the objects that have been used over the past 350 years here at the Royal Observatory in Greenwich. And this also includes the famous Harrison experimental sea clocks that some people might have heard about, but also a massive red ball that was built on top of the Royal Observatory, which is known as the Time Ball.
- [01:42]
Eleanor Evans
I've been lucky enough to see the time ball in action and it really is so important in this story. We will get to it in due course, but let's just zoom out a bit. We've got a lot of listeners all over the world. Why is Greenwich so important to this broader story? Why do you find yourself working there?
- [01:58]
Dr. Emily Ackerman
Greenwich plays a very important part in the history of time measurement, in particular to the history of accurate time measurement for astronomical and navigational purposes. There are many reasons people might measure time. Humans have been doing this for millennia. They might want to know when to harvest, when to sow. If you're living in an area where there's drought or monsoons, you might want to know when you can expect these. But Peace Paul also looked to the the heavens, as they believed that life was determined by the gods and that looking up to the sky would help. So we have a very entrenched relationship with the universe around us. So in terms of accurate time measurements, you can look at what I've just described is more like larger scale. On a smaller scale, you can track the day or the night using some kind of device that breaks it down into intervals. So for us, the sun is very important in our timekeeping because that determines our day. So that's the rotation of the Earth in relation to the sun. People have used sundials to divide the day into hours, and at night they might use water clocks, or if there is no sun, because the sundial won't work if there is no sunshine. So if it's cloudy, you could also use a sand timer. So basically, this is measuring intervals that you can then use, or the length of a prayer on a ship. You can give an audible signal for a market to start. So this is all how human societies interact with time. However, the accurate measurement of time is particularly relevant to astronomers and later navigators.
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Eleanor Evans
And today we're going to be looking at a particular moment or a few moments around Greenwich in particular. It starts in the 17th century, I believe, when we're looking at bigger problems of navigation, of need for timekeeping, accurate timekeeping. What can you tell us about what happens at this time?
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Dr. Emily Ackerman
Time? So in the late 17th century, there are some important developments, one being the development of a pendulum applied to clock making, which hugely improves the accuracy of time measurement by mechanical clocks. So before the pendulum, you have mechanical clocks that people use in their daily lives, but they're not very accurate. They might be 10, 15 minutes fast or slow a day. This is fine for social life, but it's not great for astronomers who like to use time to measure the positions of the stars. So because the earth rotates 360 degrees on its axis in 24 hours, you can use time to measure this rotation, which gives you a sense of where the stars are and the planets are. So time is very important to astronomy and accuracy is very important to measure precisely the movements of the sun, stars and planets. And the pendulum improves its accuracy from, say, 10, 15 minutes a day to seconds, or, you know, under a minute a day. So that's a huge increase. And the other important development is the establishment, the building of the Royal Observatory 350 years ago in 1675. And it was developed, it was built to accurately map the stars so that these could be used for navigators at sea to find their longitude.
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Eleanor Evans
So the challenge of longitude was causing a real problem at sea. Can you take us a bit closer to this problem? Why was it such an issue?
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Dr. Emily Ackerman
Yes, so the challenge of longitude in the 17th century was one for European trading nations who wanted to find more accurate method than they had to determine longitude. So if you imagine the Earth and we all know the lines of latitude, so your position north or south, and the lines of longitude, which is your position east, west, you use these to determine where you are and where you're going. The problem they had with longitude is they were able to measure latitude by using the height of the star over the horizon, but they could not do the same for longitudes. Both are quite complicated processes involving spherical trigonometry and lots of mathematics I will not go into. But the basics of latitude is that you have the pole and the equator as natural reference points, but you do not have a natural reference point for longitudes. So basically, longitude is determined by the Earth spinning 360 degrees on its axis in 24 hours. So if you know a time difference, because The Earth spins 180 degrees in 12 hours and 75 degrees in 5 hours or 45 degrees in 3 hours, if you know a difference in time between two locations, you know your longitude. The problem was, is in the 17th century, there was no way of knowing your time at a different location. So, you know, a watch, a quartz watch or a GPS connected smartphone did not exist. So that was their major problem. They couldn't determine the longitude astronomically like they could the latitude. And what they did instead was they had a method known as dead reckoning, where they would keep track of the ship's speed, its direction and taking in account currents and other variables, and they would keep track of the ship's estimated position. Now, they were very good at this, but if it went wrong, it could go very wrong. So for European nations, they just wanted a better method than dead reckoning to find their longitude.
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Eleanor Evans
Yes, you can see why they would need a better method. With trade burgeoning and navigation so on really necessary. So it's established under the patronage of Charles ii. Can you take us into the place that is built at Greenwich? What's it like? What can you see there?
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Dr. Emily Ackerman
Oh, it's beautiful. It's quite a small site for something that's had such big impact on the world. But the original building from 1675, designed by Christopher Wren, is a beautiful red and white brick building. It's got a beautiful facade and you can see this down in Greenwich. If you look up the hill, there sits the Royal Observatory facing you. Funnily enough, it was built on the foundations of an old said castle or hunting lodge that was used by the King. And as a result, it's actually not Very well positioned for the work that was done here. Basically, the telescopes needed to be aligned on a north south line, and the original building is not aligned to the north south. So that's why if you come here, you'll see additional buildings built to the side which ultimately came to define the Prime Meridian. So we had multiple meridians throughout the history where people kept upgrading their telescopes and, you know, establishing a new telescope, a new position within in the building and measuring the stars and thus time. And so what you see when you get here is the original 1675 building and then centuries of development of instruments, timekeepers and buildings. So it's fascinating. I'm sat. I don't know how many degrees, I don't know the difference in time, but I'm sat slightly to the east of the historic building under a massive telescope. The great equatorial was, which was built in the late 19th century. And I can continue further east towards our planetarium and another beautiful building that has some telescopes.
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Eleanor Evans
Must be remarkable to be in such a place that so clearly visually tells this story of the evolution of how we understood our place in time and space. That's. That's so cool. So, to return to this longitude problem, am I right that the first person put to this task, or one of the first people, is John Flamsteet? What was his first role?
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Dr. Emily Ackerman
He was the Astronomer Royal and he was appointed by King Charles when the observatory was built, basically to make a map of the stars so that they could perfect the art of navigation by finding the longitude of places. Flamstead installed the most incredible clocks in the observatory. So although he was appointed by the King, he wasn't actually given any money for instruments. So he had a wealthy patron, Sir Jonas More, who had these clocks made for him by London's leading clockmaker of the time, Thomas Tompion. He's very well known in horological circles and these were incredibly impressive clocks. They were built into the building, so in what was known as the Great Star Room, a nice octagonal room, really high ceilings. The pendulums were built behind the paneling in the walls and they were 13ft long and they were suspended from the ceiling and they swung back and forth. They also had a huge weight, so they only had to be wound once a year. And he had two of these clocks installed and had lots of teething problems because the conditions of the building weren't great. So there was a lot of dirt and dust and debris and they kept stopping and to get the clockmaker to come and help sort it out. But eventually Flamstead used these clocks to prove something that was fundamental to the work, that was to go into helping navigators at sea, and that remained the basis for our timekeeping for the next 250 years. But he proved the theory at the time that the Earth spins at a constant rate, and that was fundamental to the work that Flamstead was to do, was that the Earth rotates at a constant speed. And using these great clocks, he proves that theory. It's not. So that's not the case, we know now with far more accurate instruments, but back in the day, with what the accuracy that they could achieve with the clocks. This was an important development and allowed the subsequent centuries of work to be done here at Greenwich.
- [11:15]
Eleanor Evans
So John Flamsteed's work and that of his contemporaries are obviously really important to this story. People will know that something significant happens here because soon enough there's Greenwich Mean Time. Can you take us exactly into when this comes to the fore?
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Dr. Emily Ackerman
Yes. So this is quite a gradual process, really. So Greenwich, meantime, is used by John Flamsteed and later Astronomer Royles to map the stars and to create data, star data, data about the moon and its movements and prediction about the future movements of the moon so that navigators can use this at sea. So this is all tied up in the methods for finding longitudes that are developed in the 18th century. And part of these developments are the developments of portable timepieces, marine chronometers. Yeah. So during the 18th century, these methods are developed, they're put into use, and this means that when sailors are navigating, Greenwich becomes like an anchor point for them, and it becomes the basis for charts and maps. The data is made at Greenwich and Greenwich Mean Time is basically the time at which you're using as your reference time for longitudes. And all the data is the star data that sailors are using in the Nautical Almanac is rooted in Greenwich. So it becomes really important for hydrography, for charting, for navigation, but not for you or me. This is a later development. So the Royal Observatory, then, because they're so good at measuring time, becomes tasked with looking after the chronometers that belong to the Royal Navy. So the government has a stock of chronometers that they lend out to voyages. And it's at Greenwich, it's actually in the office where I'm sitting now, that lots of these chronometers were tested against the regulators. This is when you get people in Greenwich needing Greenwich Mean Time, because chronometer makers are basically sending their chronometers to be tested at Greenwich. They're competing because Greenwich runs trials to, you know, to promote, like, even better accuracy in chronometers. So the chronometer makers will have their chronometers trialled here and the best ones will be bought for the. For the governments. So they start using Greenwich Mean Time. And because of Greenwich's ability to measure accurate time and to share it, Greenwich becomes increasingly important.
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Eleanor Evans
You mentioned this brilliant item at the observatory, the time ball. Where does this fit in the story? What can you tell us about that?
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Dr. Emily Ackerman
Yeah, the time ball is great. And there used to be a lot more of them. There are still some around the world and Greenwich is a very iconic one. It's now red, but it used to be black. But it was very important for navigators. So when the portable, accurate marine chronometer was developed in the late 18th century and it became used on ships, you know, increasingly used in the 19th century, the problem was that a chronometer, although it's very accurate, it's not precisely giving you the time. It's either gaining or losing, losing some seconds each day. So that's not a problem. You just need to keep track of how much it's gaining and losing. But you can only do this via astronomical methods, which is quite time consuming. So what the time ball did was, if you're down in the Thames in your ship, all you have to do is, at one o' clock each day, look up, the ball is raised on its mast before 1 and at exactly 1pm, it drops. So all they had to do was watch the time ball, look at their chronometer, note the time that it was showing compared to the time ball, and they knew the error of the instrument. And, yeah, these were found in ports all over the world for shipping and navigation. And there was even one on the Strand as a public time signal that was connected directly to the Royal Observatory and dropped by the electric signal.
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Eleanor Evans
And people can still see the time for today dropping on the days with the right conditions. Right?
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Dr. Emily Ackerman
Yes, we drop it every day at 1pm we drop it at British summertime at 1pm so as not to disappoint people and have to make them figure out whether we're GMT or BST. But, yes, every day, 1pm, you can come and watch it drop, unless it's really, really windy, in which case we have to keep it down because there is a chance it might get damaged. And they face the same problems back in the 19th century.
- [15:19]
Eleanor Evans
Well, fingers crossed. If any, any of our listeners make their way, they get to see it because it's a really, really, very cool site.
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Eleanor Evans
It right that coming much later, there are Other developments at Greenwich that make time even more accessible for the average person, that standardize this even more.
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Dr. Emily Ackerman
Yes, there are certainly. So throughout the 18th century Greenwich mean Time, accurate time is really only important for astronomers and navigators. However, in the 19th century, so mid 19th century, during industrialization, and you have the railways starting to run, well, they'd been running for a bit longer, but increasingly people were using the railways, and this meant that people were traveling faster than they were before. And this had an implication for time because previously travel was slow and people lived by their local time. And the clue is in the name. Greenwich Mean Time is the time at Greenwich by the sun. But if you're in Bristol, you're using Bristol, meantime. And the sun takes slightly longer to appear at noon in Bristol than it does in Greenwich. So, you know, we see the sun rise in the east and set in the west because we're rotating. So that means when the sun is overhead at Greenwich, it's not yet overhead at Bristol, that takes a further 10 minutes. So from east to the west coast of England, you have a difference of about 30 minutes in time. That's how long it takes the sun to traverse. So that's not that much like, for example, in the United States, it's over three and a half hours from east to west. That's more significant. But with the coming of the railways, even that 30 minutes was significant for Britain. So this is where suddenly more people need the time. And this is where the Charles Shepard sympathetic clock system comes in. Alongside the railways, you have the telegraph cables running, and this allows the Royal Observatory, so the Astronomer Royal at the time, George Airy, a very industrious figure who had lots of connections with businesses, he had really good connections with the telegraph companies and the Southeastern railway companies. And he sets up a time system that shares the time from the observatory, where it's very accurately measured with the railway. So they can use this for the timetables, because if they don't, what they have is you might have a train running from London to Liverpool. On the way up, it would run on London time, but on the way down, it would run on Liverpool time. So it could get quite confusing. So the shepherd sympathetic system, as it's known, is basically a motor clock, or a normal clock, as it was called at the time, which is electrically connected by galvanism, as they called it at the time, to other dials within the observatory. And there's also the gate clock outside the observatory. It's one of the first things you see if you come up the hill and then it was further sent. So these cables were then connected to the telegraph wires running alongside the railway, so these time signals could be sent to the railways. And prior to this, if you wanted accurate time, you had to physically transport it with an accurate timepiece. So what they had to do at the observatory itself was if they're trying to compare the time between different departments, they have to physically walk around with a chronometer. And before the shepherd system electrically collected, you had the Belleville family, who sold the time to London by visiting the observatory with an accurate watch, checking its time against the accurate time here, and then walking or I don't know which public transport was available at the time, but heading to London and selling the time to people who needed it. So it was a big development, selling the time.
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Eleanor Evans
Sorry, can I pick up on that? How would one sell you the time?
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Dr. Emily Ackerman
Basically, you just subscribe to their service. So you subscribe to the service. I don't know what they paid. And then the Belleville. So it was started by John Belleville, the father, who was an assistant here at Greenwich, and later carried on by his wife, Maria Belville, and then subsequently by the daughter, Ruth Belleville, up until the 1940s. So a good hundred years.
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Eleanor Evans
Yeah. That's very entrepreneurial, isn't it? Seeing the gap and then just going for it. Wonderful. So, moving on in this story, then, you've mentioned Airy. I wonder if we can come back to him a bit as a figure, because he's also really important in another very famous development in the history of time and timekeeping, isn't he?
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Dr. Emily Ackerman
Yes. So George Airy, alongside the Shepherd's Sympathetic System, installed in the 1850s, was his newest telescope. So, as I said, they were updating their telescopes and moving these along in the buildings. So in the 1850s, George Airy installs. The Airy transit circle is a huge. Well, probably not to today's standards of telescopes. Back in the day, a huge telescope, very accurate, which was used to measure the transits of stars. So a star crossing the meridian, the north south line, and these were used for the nautical almanac, for navigation and also for time. So it's a lovely relationship because basically you observe the stars to measure time, but you also use time to map out the stars. And they had what they were known as clock stars, which were stars that were so well known that they used these to calibrate their clocks. So, and this was all connected electrically, so it was easier for the staff to do their work. Just over 30 years after Airy installed the transit circle. In 1884, there is a conference in Washington to discuss the adoption of a prime meridian for the world. And basically, delegates come from various countries to vote on this idea. It's been spoken about before, and they agree that there should be 10 longitude for maps and charting. This is because prior to this, a lot of charts use Greenwich as 0 degrees longitudes, but there are also charts using Paris as 0 degrees longitude or Washington as 0 degrees longitudes. So you have sea charts, land charts, and often the land chart would use the capital of its country for zero degrees. But because this can cause confusion and it means if you've got, you know, you have to know which chart you're using. What's, you know, if 0 degrees is Paris or Greenwich, it's easier if you just all use the same thing. This is just all to do with standardization of measurements and things. So they come together to discuss this and there's days and days and days of discussion, but eventually Greenwich is selected to represent zero degrees longitude. And it's due to the hundreds of years of work that has gone on at the Royal Observatory, because all the astronomical observations that have been done, they have been used at sea for centuries. Charts are based on these observations. And therefore it said that about 72% of shipping was, or the tonnage of shipping was using charts based on the Greenwich meridian. And it was therefore the practical solution to use Greenwich. There were other potential areas, but the biggest discussion that took, I think, a day or two, or at least a session or two, was, could we have a neutral prime meridian? And basically the idea of a neutral prime meridian would be one running through the Pacific Ocean, through the Bering Strait. So it's not rooted in a particular country. However, you need a telescope to define the meridian, or as some suggested, you use a meridian and you calculate the longitude from there. But then you can't do your measurements on that prime meridian, which people thought was essential. But they also pointed out that even if you say it's so many degrees of longitude from that observatory, it's still that observatory. So it's neutral in disguise. I guess it's still not neutral. So they debate this for a long time. So the debate is really, can we have a neutral meridian? And the result is this is seen to be too impractical. It has to go through a telescope, and eventually it goes through the telescope at Greenwich.
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Eleanor Evans
So decided in 1884, the late 19th century. And the prior meridian still runs across the courtyard at the Royal Observatory, Greenwich today. For listeners who might not have walked along it or know even what it looks like. What are we talking about here?
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Dr. Emily Ackerman
Yeah, so this is really interesting because, yes, it runs through Greenwich, but it no longer runs through the AIRY Transit telescope. So it ran through there for a good hundred years. So it's our historic Prime Meridian. It's great for photos because you can either have a lovely view of London behind you or a lovely view of the building. People love the courtyard yards because we have like a line marking the meridian and people love it. But, but the important part is the telescope that is, that's defining your meridian. And it runs all around the globe, of course, 0 degrees and then it's 180 degrees. But the interesting thing is because we've moved on so much in our technologies and how we measure time, we now no longer use telescopes and pendulum clocks. We use atomic clocks and satellites. And therefore the, the Prime Meridian now the 0 degrees is actually about 100 meters east of the Airy Transit Telescope.
- [26:29]
Eleanor Evans
So for all the tourists who are visiting the courtyard then, and perhaps having one foot either side of this Prime Meridian, the real ones are a little bit further away. But it's still a wonderful visible representation of this broader story that is told at the observatory. Right. And you mentioned the technology's moved on a lot since then. GMT is obviously very important still as a system of time that matters in our own calendar. But globally there's a different standard. What happened in the later 20th century, that meant that GMT took perhaps a backward step.
- [27:03]
Dr. Emily Ackerman
Yeah. So in the later 20th century, and this is interesting because this is why I brought up Flamsteed's work with the great clocks earlier, is that the technology of pendulum clocks increases so much that they become so accurate that what was known, again, this was known in theory, but it's proving it or measuring it, they became so accurate that they actually allowed astronomers here to measure that the Earth does not rotate at a constant speed. And because the definition of the second was based as one part of, you know, of a 24 hour rotation, because that rotation isn't constant, that means your second isn't constant, which isn't great as a basis of measurement. So there are some more developments. There's quartz technology which greatly improves the accuracy of timekeeping. And these are used at Greenwich. And later atomic timekeeping develops. Greenwich plays a central role in setting up these time standards, but it's becoming more global. So you have timing centers all over the world now using atomic clocks. So this is when the redefinition of the second comes in. And it's now based on the frequency of a cesium atom. So at the base of atomic clock is a cesium atom. It's hugely complicated, Utterly fascinating. So Greenwich Mean Time is actually no longer measured because Greenwich Mean Time is time measured by the sun at Greenwich, by the telescopes using the pendulum clocks. And we no longer do this. So time is now measured via atomic clocks. And the time standard is atomic time. We use this as universal coordinated time, which is basically a system that unifies our older timekeeping system with our current atomic timekeeping system. And it's measured by atomic clocks through laboratories across the world. So it's a global endeavor. And I don't know how many. It's. I think the number is always increasing, how many clocks contribute to it, but it's. It's an averaged out. And in the uk we use utc, which is measured by the National Physical Laboratory in Teddington. The relationship between the Royal Observatory Greenwich and the National Physical Laboratory in Teddington goes back to the 1930s or 40s with the experiments of the short pendulum system, which was very, very accurate, and the quartz clock and later atomic timekeeping. And it continues today because we recently had this wonderful acquisition, which is a strontium ion trap clock, I believe, if I say it correctly, which is one of the newest atomic clocks that are being developed. So these are so much more accurate that it said that they are thinking of redefining the second again just because it's also more accurate.
- [29:44]
Eleanor Evans
I think that's just fascinating to hear because I'm so guilty of just thinking that we're at a time now where we know what time it is. And I check my watch and I just look at that and think it's not something that's still evolving. So it's really interesting to hear that it's. This is still something that's very much in progress.
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Dr. Emily Ackerman
Yes, very much. And it's also still in progress in astronomy and navigation because there have been experiments with the deep space atomic clock. And I like to think that that story has similarities to the development of the marine chronometer in the 18th century, is that they're now developing a very accurate portable clock for space exploration that allows them to navigate even more accurately in space. So it's, yes, a continuous story, Quite.
- [30:27]
Eleanor Evans
A legacy for Flamsteed and the work he was doing at Greenwich then.
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Dr. Emily Ackerman
If only he knew.
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Eleanor Evans
How would you think people should be considering GMT today? What would you like people to be bearing in mind?
- [30:37]
Dr. Emily Ackerman
It's just a. It's a fascinating concept. If you break it down into Greenwich, Mean and time, you just learn so much. You learn about time measurement, you learn about why is it mean time, you learn about why is it in Greenwich. And that's all tied up into the history of the Royal Observatory and the history of navigation and the development of accurate timekeeping.
- [30:57]
Eleanor Evans
Finally, Emily, if we could just turn to some of the objects that you work with. I wonder if you could introduce us to just a few instruments or timepieces we haven't been able to touch upon in this very quick rattle through this very big story that really bring the story to life for you.
- [31:12]
Dr. Emily Ackerman
So the obvious ones to talk about are the Harrison timekeepers. So basically these are four timepieces that John Harrison, a carpenter from the north of the country, developed during the 18th century as an attempt to gained the 20,000 pound reward for the Longitude Act. And he basically creates the first time keeper that keeps time accurately enough at sea for navigation. And from this you get the birth of the marine chronometer and the widespread use of chronometers in navigation. So these are fantastic objects on display in the Royal Observatory, but we also have a wealth of objects in our stores, so we do behind the scenes tours to see these. And one of my favourite favorites is an alarm clock, which many people don't like. But this was a very special alarm clock made by Thomas Taylor, who was an assistant here in the early 19th century, and he devised a star clock, a star alarm clock. And in the dial, it's beautiful. It's a quite simple square timepiece, not very large, and it has all the names of different stars engraved on the dial. And what it did was it gave a little notification ping whenever an important clock star was about to transit. So it would notify him that he had to get ready to go and observe, because before he was using a regular alarm clock, and he was worried, as he writes at the time, that if he missed the alarm or forgot to set it, not only would he miss one observation that night, but he wouldn't have reset the alarm for all the subsequent observations and therefore miss a whole night of observations. So he makes this wonderful clock, he earns a prize. And Thomas Taylor himself is fascinating because there are some letters relating to his life and he complains about having to work so much at the observatory that he barely has time to run down the hill to get his lunch. And he writes to the hydrographer, I believe, asking for more pay for the assistance, because they aren't paid very much. So he's a fantastic figure who worked here. And yes, and the alarm clock is, is just a great symbol of his ingenuity.
- [33:17]
Eleanor Evans
I think it's a shame we can't touch on it more in this episode. But the Royal Observatory does hold so much really interesting domestic and social history as well, doesn't it? Because families lived there. Wives and children were involved in this work too, weren't they?
- [33:31]
Dr. Emily Ackerman
Yes, they were. They were. And that's why if you visit Flamstead House, all the additional buildings when it was a family dwelling, I mean, it's tiny inside. When you go into the apartments, they're tiny. But when John Flamstead and his wife Margaret had no children, but later astronomer royals had bigger families and they extend the building to fit their growing families. And some of the children did like watercolor paintings of the observatory. So we have a great one of the Time Ball. When it actually did, the mast broke due to high winds and it fell into the courtyard. So we have a beautiful watercolor of this. So, yeah, it's a, it's a brilliant place. And then you have all the assistants who worked here and who lived around the area in Greenwich.
- [34:10]
Narrator/Podcast Host Introduction
That was Dr. Emily Ackerman, curator of Time at Royal Museum's Greenwich. She was speaking to Eleanor Evans. And you can find out more about the observatory@rmg.co.uk don't miss our mini documentary too, filmed on location at Greenwich, which takes you inside the famous site that's available now on the History Extra YouTube channel or ad free in the History Extra app.
- [34:40]
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