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- [00:01]
Professor Susannah Lipscomb
Want to walk the halls of Anne Boleyn's childhood home or explore the castles that made up Henry VIII's English stronghold? With a subscription to History hit, you can dive into our Tudor past alongside the world's leading historians and archaeologists. You'll also unlock hundreds of hours of original documentaries with a brand new release every single week covering everything from the ancient world to to World War II. Just visit historyhit.com subscribe
- [00:35]
Archie Manning
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- [00:55]
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What's going on?
- [00:56]
Archie Manning
I'm Archie Manning, Vuori athlete and college quarterback. Whether I'm running, training, traveling, or just unwinding at home, I love doing it in my core shorts from Vuori. With a breathable box of brief liner, they're quick to dry, super versatile, and stand up to even my most intense training sessions. Plus, they come in three inseams and a ton of colors. Ready to try a pair? Go to vuori.com arch and get 20% off at checkout. I think you're going to love them as much as I do. That's V-U-O-R-I.com arch and get 20% off your first order. Exclusions apply. Visit the website for full terms and conditions. Not only will you receive 20% off your first purchase, but enjoy free shipping on any US orders over $75 and free returns. Have a great day. Best thing that's ever happened to you financially. Go easy. Sold my car on Carvana. Amazing offer, really. I hit 200 on a scratcher. Did the scratcher come to your house and hand you a check?
- [01:37]
Fin AI Representative
No.
- [01:37]
Archie Manning
How many scratchers did you hit to get that? I hit a button on Carvana.com once.
- [01:42]
David K Love
Okay, that's fair.
- [01:43]
Archie Manning
It's like the lottery, except you always win. Not like the lottery at all, actually. Exactly. Inexplicably good offers. Worth bragging about. Sell your car today on Carvana. Pick up. These may apply.
- [02:01]
Professor Susannah Lipscomb
Hello, I'm Professor Susannah Lipscomb, and welcome to Not Just the Tudors from History Hit the podcast in which we explore everything from Anne Boleyn to the Aztecs, from Holbein to the Huguenots to from Shakespeare to samurais relieved by regular doses of murder, espionage and witchcraft. Not, in other words, just the Tudors, but most definitely also the Tudors. In the winter of 1684, inside a London coffee house thick with tobacco smoke and the animated voices of men engaged in heated discussion, Edmond Halley posed a question that would change humanity's understanding of the universe. If the planets were poured towards the sun by an invisible force that weakened with distance, why did they move in ellipses rather than circles? Around him sat some of the greatest minds in England, Christopher Wren, Robert Hooke among them.
- [03:06]
David K Love
And.
- [03:07]
Professor Susannah Lipscomb
But no one could supply the answer. Halley knew there was one man who might come up with a proof. A reclusive Cambridge mathematician named Isaac Newton. Edmond Halley's story begins long before the famous comet that now bears his name streaked across the skies of Europe in his lifetime. Born in London in 1656, the son of a prosperous soap maker, he came of age during a scientific revolution that was dismantling ancient ideas about the cosmos. For centuries, astronomers had imagined the heavens as fixed and perfect, governed by circles and divine order. But by Halley's lifetime, Copernicus and Kepler had already shattered that certainty, replacing it with a universe in motion. As a young man, Halley pushed that revolution further. Leaving Oxford, he sailed to the remote island of St Helena in the South Atlantic to to map a sky that Europeans had barely studied. His observations earned him acclaim and entry into the Royal Society, placing him at the centre of England's emerging scientific world. In this episode, I'm delighted to say we're joined by David K Love, whose book Edmund Halley the Many Discoveries of the Most Curious Astronomer Royal reconstructs Halley's extraordinary life and achievements. Beyond the comet, Love reveals a restless and ambitious figure. An astronomer obsessed with navigation and longitude, a traveler fascinated by magnetism and the Earth itself, and the crucial champion of Newton's Principia Mathematica, the work that transformed modern science. I'm Professor Suzanne Lipscomb. Welcome to Not Just the Tudors from history hit. Welcome, David.
- [04:52]
David K Love
Thank you very much. I'm very pleased to be here.
- [04:54]
Professor Susannah Lipscomb
It's a wonderful opportunity to have you on to talk about many different scientific ideas, actually, that Halley comes in contact with. But before we get onto him, can you paint a picture for us of what astronomy looked like, let's say, before the 16th century? What ideas was he challenging or building upon?
- [05:17]
David K Love
Mm. I think it's an excellent idea to give some idea of the historical background because then people will understand where he is coming from. And I'm afraid that means going back as far as the ancient Greeks, which I realize is outside the normal sort of time frame of your podcasts, but it'll be pretty short. The reason we go back to the ancient Greeks is because, as far as we know, they were the first people ever to try and develop some sort of a physical understanding of what was happening up there in the sky. And they came to a number of conclusions, the first of which is that the Earth was a sphere, it wasn't flat. But then they said, well, obviously the Earth is at the center of the universe, and everything in the universe obviously goes round and round the Earth in perfect circles at uniform speed. Now, that worked very well for the stars, which did indeed seem to go round the Earth once, roughly every 24 hours. And it sort of worked moderately well with the sun and the Moon. Where things came unstuck was with the planets, which had this peculiar forward, backward, forward motion, or seemed to. So they travelled from west to east a lot of the time, and then for no obvious reason, started moving in the opposite direction for a few weeks or months before resuming their direction that they originally had. And, you know, this was a bit of a puzzle to the ancient Greeks, but they developed mathematical systems that they felt could account for it. And this was more or less the system that was believed for the best part of 2,000 years. And then the big breakthrough, of course, came with Copernicus, born 1473 in what is now Poland. And Copernicus's key insight was that you could understand this weird planetary forward, backward, forward motion much more easily if you assumed that the Earth was just another planet along with the other planets, and they all went round and round the Sun. And then this very strange forward, backward, forward motion would happen automatically as the Earth overtook one planet or another planet overtook the Earth. So that was his big breakthrough. Unfortunately, he stuck to the concept of circular motion at a uniform speed. So the results, in terms of predictions of future planetary positions that came out of his system, weren't actually that much better, if at all, than what the ancient Greeks had come up with.
- [08:10]
Professor Susannah Lipscomb
So do we need to bring Kepler into the story here?
- [08:14]
David K Love
We absolutely do, because Kepler was the big next breakthrough. Born in 1571, he was a German astronomer and he had the good fortune to be left a whole mass of observations of the planet Mars. And he was able to use those observations to demonstrate that Mars actually went round the sun in an ellipse, not a circle. By extension, therefore, the other planets did as well. So this was his first law of planetary motion. He was also able to demonstrate that Mars didn't go around the sun at a constant rate. When it was closer to the sun, it went more quickly, and when it was further away from the sun, it went more slowly, such that, as he put it, the planets swept out equal areas in equal times. And those were his first two laws of planetary motion. And with them he was able to make forecasts of future planetary positions that were much more accurate than anybody else had managed up until then. And this was one of the main factors causing people, at least educated people throughout Europe, to come gradually to accept that it was the Earth that went round the sun rather than the other way about.
- [09:34]
Professor Susannah Lipscomb
That's such a useful background to help us understand what's advancing during Halley's lifetime. But tell me about Edmond Halley. Who was he, when was he born? What sort of family was he born into? And what did that mean for him as he started out on his scientific journey?
- [09:52]
David K Love
Kepler died in 1630. Halley was born in 1656, the son of a prosperous soap maker who was also quite well connected. And Halle's father had a number of properties in and around London. Money was never a problem for his father, or indeed for him. And he was obviously a very bright boy because his father sent him to St. Paul's School in the centre of London, next to the cathedral. And of course it burnt down in 1666 along with the cathedral, but the school had to have its lessons elsewhere for a while. But anyway, Halley obviously did very well there, because in 1672 he became head boy of the school. And then in 1673 he went on to Oxford University, where he studied the physical sciences, including astronomy. And I suppose if we want to understand what he did next, we have to move on to the vexed problem of longitude.
- [11:01]
Professor Susannah Lipscomb
Yes, tell me about this, because the problem of determining longitude at sea seems to have been a very beginning in the 17th century. Why was it so elusive?
- [11:12]
David K Love
It was a big deal, I think. Commercial shipping was growing in extent and people needed to know where they were. But that is the problem. If you're a ship in the middle of the ocean and you can't see any land anywhere, how do you know where you are? I mean, it's all right for us, we've all got mobile phones and we can just push a few buttons and find out our latitude and longitude to six decimal places in a fraction of a second. But it wasn't at all like that in those days. Latitude was easy. All you had to do was observe the height of the sun above the horizon at midday, or alternatively, observe the height of the pole star above the horizon during the night, and either of those would give you a pretty good measure of latitude. Longitude was a different matter. How on Earth do you measure how far east or west you are of an essentially random line, say a line of longitude going through Greenwich, for example? That's a lot more tricky. One of the methods being proposed at the time was something called the lunar distance method, which, if I can explain that briefly, it relies on using the Moon. As the name would suggest, the Moon moves relatively quickly against the background of the stars, so it moves about half a degree every hour or so. So you can use the Moon as a sort of clock in the sky. Now, if you measure the angular distance between the Moon and a known fixed star, and you happen to have with you an almack, which tells you what the time is at Greenwich, when that will be the case, and you know your own local time, then the difference in those two times gives you your longitude. So if you're, say, one hour behind Greenwich, that means you're 15 degrees to the west of Greenwich. If you're two hours behind Greenwich, it means you're 30 degrees to the west of Greenwich, and so on. Now, the lunar distance method is actually a tiny bit more complicated than that, but I think that gets to the essence of it. And can I, at this stage, mention Charles II's mistress?
- [13:36]
Professor Susannah Lipscomb
I would love it if you mentioned Charles II's mistress. Well, this is Louise de Carouay.
- [13:41]
David K Love
That's right, yes. She played a pivotal role in introducing Charles II to a French astronomer, Sieur de Saint Pierre. Now, Sieur de Saint Pierre reckoned he could measure longitude, and it seems to have been by this lunar distance method. He must have explained it to Charles, who farmed the idea out to a committee which included such luminaries as Christopher Wren. And the committee had a look at it and said, well, wonderful idea. Yeah, in principle, but in practice, sorry, it wouldn't actually work. And it wouldn't work because we don't know the positions of the stars sufficiently accurately and we don't really understand the orbit of the Moon sufficiently well. But they said we could do something about that. What we could do is we could found an observatory, say, Greenwich, would be quite a good place. And what we could do then is spending the next few years measuring far more precisely positions of stars and the orbit of the Moon, and then we might be in a position to actually apply this lunar distance method. So a working party oh, it was. I should say that it was Christopher Wren who suggested the site at Greenwich and a working party which included him and Robert Hook, another important person in the Royal Society, and somebody called John Flamsteed, who was a very capable astronomer and who was going to end up as being the person in charge of this observer at Greenwich and was therefore going to become our first Astronomer Royal, though he didn't know that at the time. And also there was Edmond Halley getting in at the ground floor, because while he was at Oxford University, he'd corresponded with John Flamsteed and they'd done a bit of. And at that stage they were very good friends, so he was able to go along in this working party as well. Everyone agreed it was a good site. The foundation stone was laid in 1675 and the building was complete in 1676, at which time John Flamsteed started work. And Halley should have just gone back to university to finish his studies at
- [16:07]
Professor Susannah Lipscomb
Oxford, but he didn't. What does he do instead, David?
- [16:11]
David K Love
He realised that there was a bit of a problem with what John Flamsteed was doing. Flamsteed, by definition, could only observe stars visible from the northern hemisphere, specifically from about 51 degrees north of the equator at Greenwich. What Flamsteed couldn't do, by definition, was observe stars that could only be seen in the southern hemisphere. But nevertheless, it would be very useful if somebody could go down there and actually observe as many stars as possible. So this is exactly what Ali decided to do. So he went off to the island of St. Helena where he spent a whole year observing as many bright stars as he could and fixing their positions as accurately as he could. It wasn't easy, but by any means, because St. Helena turned out to be a lot more cloudy than he had been led to believe, so he had to waste a lot of nights just looking at endless banks of cloud. Nevertheless, after 12 months there, he'd managed to fix the positions of about 300 bright stars. And so he returned to England.
- [17:22]
Professor Susannah Lipscomb
I mean, it's extraordinary achievement. This is a man in his, what, early 20s at this point in time?
- [17:28]
David K Love
He was about, yeah, 20 or 21 at that time. Yes, absolutely extraordinary. He was a very capable person and the money from his father helped, of course, because he was able to buy top class equipment to do all this observing. But, yeah, a lesser man would not have managed it. And this, I think, explains why he returned to something of a hero's welcome when he got back to England, I mean, he published the results of his survey as soon as he could. And within a few months, the Royal Society made him a Fellow of the Royal Society. And for someone who had only just reached the age of 22, that was really incredibly good going. And, oh, the bit I like. Charles II was so impressed that he instructed Oxford University to award Halley his degree, even though he hadn't actually sat the final exams.
- [18:29]
Professor Susannah Lipscomb
How wonderful. Yeah. Do we know anything about what was going on in Halley's private life at this time?
- [18:34]
David K Love
Ah, I've got to get it in at some stage. But although we know a lot about his professional life, it's very well documented all over the place. There are occasions where we know very little about his personal private life and it can be very irritating because we'd like to know a lot more than we do. We know. At this stage, the Royal Society saw him as a very useful person to have around and decided to send him off to Poland to visit Johannes Hevelius, who was a Polish astronomer carrying out a similar sort of survey to John Flamsteed. And the Royal Society wanted to get an idea of exactly what he was doing it and how he was doing it. So we do know he spent about eight weeks in Poland before returning to London. When he got back to London, we do know that he went on an extended holiday in France and Italy. When he was in France, he went to Paris, where he met Giovanni Cassini, who is the famous Italian astronomer who at that time was in charge of the Paris Observatory. And then when he got back to England after that was early 1682. We do know that he married a young lady by the name of Mary Tooke. But this is where it does get infuriating, because we have no idea when he met Mary Tooke, where he met her, how long they'd known each other for, when they got engaged, where she came from in the first place. None of this information do we have. All we know is they got married in April 1682 and went to live in a house in Islington, which at that time obviously was just a little village just outside London.
- [20:22]
Professor Susannah Lipscomb
Yes, and I imagine the name Mary Took is sufficiently common to make it very hard to trace through the records.
- [20:30]
David K Love
Nobody's ever managed to come up with anything significant about her. No, I'm afraid not. Very annoying. But there we are.
- [20:39]
Professor Susannah Lipscomb
Now it's a couple of years later that we get to the famous coffee shop meeting that I mentioned at the start with Halle, Wren and Hook. So take me. Up until that point, what was at
- [20:51]
David K Love
stake an awful lot was at stake, we aren't absolutely certain it took place in a coffee house, but that does seem to be far and away the most likely venue, because there's no sign of it having happened at the Royal Society. And the winter of 1683, four was an absolutely freezing cold winter.
- [21:11]
Professor Susannah Lipscomb
Oh, yes, that was the one where they roasted an ox on the Thames, I remember.
- [21:16]
David K Love
That's exactly it. The Thames froze over to such a depth that you could do whatever you liked on the Thames. They had these ice fairs and so on. It's highly unlikely that they met in the open air anywhere. So a coffee shop seems the obvious venue and most people seem to think that's probably where it was. And before I tell you exactly what they discussed, I'm afraid I do have just for a second to go back to Johannes Kepler. Kepler not only discovered his three laws of planetary motion, he also asked himself the question, why was it that the planets moved round the sun at all? Could it be, he speculated, that there was some sort of a force emanating from the sun which somehow pushed the planets around in their orbits? Now, he was actually the first person in human history to think up this idea, and he deserves a great deal of credit for it. His ideas about how this force emanating from the sun might actually work, it has to be said, were completely wrong. But the basic idea remained. Was there a force somehow emanating from the sun which moved the planets in their orbits? And kepler died in 1630. But the idea stuck and people began to say, maybe this force emanating from the sun follows an inverse square law. The intensity of light, for example, follows an inverse square law. The intensity of light drops off on an inverse square basis depending on how far away you are from the light source. So if, say, you've got two planets, A and B, and planet B is twice as far from the sun as planet A, then planet B would experience one quarter of the force of planet A. And if planet B is actually three times as far away, then planet B would experience one ninth of the force that planet A is experiencing. So people had this idea that, yeah, it would seem to fit nicely if this force from the sun was an inverse square law. But the critical question then became, could you demonstrate mathematically that an inverse square law would result in Kepler's elliptical orbits? And that is what nobody so far had managed to do. And this is what the coffee shop meeting, if that's where it was all about. Now, Christopher Wren was mathematician, astronomer, architect, general, all round genius. He'd obviously tried to find a mathematical proof of this and failed. And the three of them were discussing this whole problem and Wren decided to offer the other two a prize of a book worth 40 shillings if either of them could come up with this mathematical proof. And Hooke, who actually wasn't a very good mathematician, said, oh, yeah, I can manage that easily. But the fact is that he never did. Edmund Halley recognised also, I think, that he couldn't do it, but he thought he knew somebody who could. He thought that there was this rather eccentric professor of mathematics at Cambridge University by the name of Isaac Newton who might be able to crack it for him, and he would probably have gone to see Newton pretty quickly after that meeting, but didn't.
- [25:03]
Professor Susannah Lipscomb
Yes. So let's talk about that delay. Is it true that it's something to do with Halley's father possibly being murdered?
- [25:12]
David K Love
I'm afraid so, yes. In March 1684, Halley's father left his house in London, as presumably he normally did, and never came back and was never seen alive again by any of his family. And his body was found seven or eight weeks later, some considerable distance away, somewhere in Kent. And it's a mystery that nobody has ever got to the bottom of. The inquest concluded that he had indeed been murdered, but nobody was ever able to establish a motive, let alone somebody who might have done it. It was a big mystery, but it did keep Halle in London for a lot of 1684, when he might otherwise have gone to visit Newton a lot sooner than he did.
- [26:15]
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- [27:14]
Archie Manning
Avoiding your unfinished home projects because you're not sure where to start. Thumbtack knows homes, so you don't have to don't know the difference between matte, paint, finish and satin or what that clunking sound from your dryer is. With Thumbtack, you don't have to be a home pro, you just have to hire one. You can hire top rated pros, see price estimates and read reviews all on the app. Download Today. What's going on? I'm Arsh Manning, Biori athlete and college quarterback. Whether I'm running, training, traveling or just unwinding at home, I love doing it in my core shorts from Biori. With a breathable box of brief liner, they're quick to dry, super versatile, and stand up to even my most intense training sessions. Plus they come in three inseams and a ton of colors. Ready to try a pair? Go to vuori.com arch and get 20% off at checkout. I think you're going to love them as much as I do. That's V-O-R-I.com arch and get 20% off your first order. Exclusions apply. Visit the website for full terms and conditions. Not only will you receive 20% off your first purchase, but enjoy free shipping on any US orders over $75 and free returns. Have a great.
- [28:19]
Professor Susannah Lipscomb
And when he visited Newton, he realized that he really was the man for the job. And Halley is often credited with making sure that one of the most important works in scientific history was published. Can we talk about that? How critical was Halley?
- [28:39]
David K Love
Oh, absolutely critical. I don't think there's any doubt about it. He went to see Newton in August and he just put to him the question, what sort of orbit would result from an inverse square law of gravitational attraction? To which Newton replied, apparently immediately, why, of course it would be an ellipse. Now Halley was delighted but said, why? Yeah, well, can you prove that mathematically? And Newton said, yes, actually I already have done. I've got the proof here somewhere. And at this point he must have shuffled round in his papers, but then very apologetically said, I'm sorry, I can't find it at the moment. I know I've got it here somewhere. I will dig it out and I will send it to you when you're back in London. So Ali had to very impatiently, I'm sure, go back to London and wait. But Newton was as good as his word. A couple of months later, he sent Halley a mathematical proof that an Inverse square law would result in Kepler's elliptical orbits. But he did better than that. He also provided a mathematical proof that a planet in its elliptical orbit round the sun would indeed move more quickly when it was close to the sun and more slowly when it was further away from the Sun. And he did better than that again, because he also mathematically demonstrated, simply using the inverse square law, that Kepler's third law would also be true. His third law sounds a bit complicated, but I promise you it isn't really. The third law simply states that the average cube of the distance of a planet from the sun, divided by the square of the time to go once round the sun is equal to a constant, and it's a constant which is the same figure for all the planets. So what Newton had done was what Kepler had seen as three isolated, unconnected, almost random laws. Newton had demonstrated all three of those laws were an inevitable mathematical consequence of an inverse square law. And this was a massive achievement. This was a huge advance in celestial mechanics. And when Halley got it, he was absolutely delighted, and he showed it to other members of the Royal Society and who were equally delighted. So Halley felt it worthwhile to go back to Newton again and say, well, look, this is absolutely brilliant, Isaac. Can you do any more than this? Because this is already a huge step forward in our understanding of the laws that govern what happens in the heavens. And Newton seems to have been very willing to respond to that because he spent the next years, year and a half, constructing what we now know as Principia. And he threw in various other extra ideas, all of which were very important to Principia. For example, he threw in the idea that this force of gravitation was not simply something coming out of the Sun. In fact, Newton realized at some stage that. That everybody in the solar system attracts every other body with a force that's proportional to their masses and inversely proportional to the square of the distance between them. We notice it much more for the sun because the sun contains roughly 99% of the mass in the solar system. So it has a much bigger effect on everything. But nevertheless, the effect is there between every other body in the solar system. And Newton also threw in his three laws of motion, and it was a combination of what is now a universal law of gravitation, not just solar gravitation, and these three laws of motion, which really were quite revolutionary. He was able to explain a whole load of phenomena that previously had not been explicable at all. And I hope we can get onto those at some stage. But I should return to the publication process to show how vital Halley's presence was. Because when Halley got this early 1686, this sort of draft of Principia books one and two, he was, you know, even more delighted. And he showed it to a number of members of the Royal Society who were equally happy with it, with one exception. And that one exception was Robert Hooke. And Robert Hooke was really cross because he said he had made this suggestion that an inverse square law might produce elliptical orbits. He'd made this suggestion to Newton many years before, and yet Newton had made no acknowledgement whatsoever in Principia that Hooke had thought of the idea first. And so he just went into a big sulk about it. And when Newton heard that Hooke was in a sulk, he responded in like kind, I should say, in case anyone doesn't know, that Newton was notoriously thin skinned and he couldn't stand the least bit of criticism of anything he said or did. So when Hooke started going on about demanding to have a bit of attention for his idea, Newton just went into a big sulk himself. And poor old Halley had to be the person to persuade Newton that he'd got to carry on producing Principia, because Newton was talking in terms of not doing any more on this thing. And Halley finally did manage to persuade Newton to continue.
- [35:01]
Professor Susannah Lipscomb
It's so interesting, the role of somebody like Halley to bring out the ideas of someone else, of genius. Is it in itself a work of genius, you know, that role as a support and patron?
- [35:16]
David K Love
Absolutely. He could see the importance of Principia. It really was revolutionary. And that what you've just said leads to the next problem. He'd finally managed to smile smooth over Newton and the Principia was ready for publication. And then Royal Society had said, well, it would fund the publication. But unfortunately it turned out the Royal Society was broke. They'd very unwisely invested a lot of money in a book called A History of Fishes, which they thought would be a big success, but apparently it was a dismal failure. And they were left with dozens and dozens of unwanted copies of this book and a big hole in their bank account. So Halley had to step forward and say, okay, I, Halley, will fund publication. This is just too important. And another aspect of his general brilliance is that he had to be the person who would proofread the book because there was hardly anyone around who could actually understand the maths in the book. And Halley was one of the few people who could. But eventually the book was published, Principia in mid-1687 to virtually universal acclaim. I think one can genuinely argue that it is the most important scientific text ever to have been produced.
- [36:43]
Professor Susannah Lipscomb
And you alluded to this slightly earlier. How did Newton's laws change the way scientists understood the cosmos?
- [36:54]
David K Love
In a variety of ways. It's difficult to know how to list them all, but one of the key things was that it united celestial and terrestrial physics. Up until then, people had thought, well, the laws that apply on planet Earth are obviously different from the laws that apply up there in the sky. Galileo's laws that he had discovered rolling balls down planes to discover laws of motion here on the Earth was seen as separate from the three laws of planetary motion that Kepler had discovered. But Newton showed that they were all the same, that actually celestial physics and terrestrial physics were one and the same thing. So that, for example, an apple falling from a tree in an orchard to the ground is obeying exactly the same laws and is experiencing exactly the same forces as the moon in its orbit round the Earth. And that in itself was a big breakthrough. But it was also a big breakthrough that Newton was able to show that the universe is highly mathematical. You can understand all the phenomena in the universe in terms of relatively small, simple mathematical laws. And his Principia and the laws that he had discovered basically dominated the physical sciences for the next couple of hundred years. And in a way, they still do. Technically, they've been superseded by Einstein's special and general theories of relativity. But in practice, Einstein only applies to at the extremes, as it were. In the normal way of things, Newton's laws are perfectly good. So when Artemis 2 went to the moon and back a few weeks ago, the calculations for its trajectory would have been done entirely in terms of Newton's laws. He is still very valid.
- [39:01]
Professor Susannah Lipscomb
How extraordinary.
- [39:02]
David K Love
Absolutely. This is a chap by the name of Augustus de Morgan, who was a 19th century English mathematician with an interest in the history of science. And what he said was this, this miracle of energy, for Halley was nothing less. Occupied himself with the question of gravitation, sought for information from Hooke Wren and Newton found out what the latter had done, induced him to begin the Principia, interested the Royal Society in its continuance, kept Newton up to his engagement, prevented him from mutilating it in disgust, undertook to see the work through the press, paid the expense of printing and made himself thoroughly master of its contents. The most difficult task of all. But for Halley in all human probability, that work would not have been thought of, nor when thought of written, nor when written printed. So, yes, Newton was the brains behind it all, but if it hadn't been for Halley, it would never have seen the light of day and the history of science might well be very different.
- [40:23]
Professor Susannah Lipscomb
He's the midwife of Newton's ideas.
- [40:28]
David K Love
Midwife is a very good expression. I wish I'd used that in my book. Never mind.
- [40:34]
Professor Susannah Lipscomb
And it's thanks to the Principia that Halley could finally calculate the cometary orbits for which he's so famous with confidence. Talk to me about Halley's own achievements in figuring out that a comet that had been observed in 1531, 1607 and 1682 were all the same.
- [40:57]
David K Love
Now that Principia was published for the first time, you had the means to work out the orbits of comets, which wasn't really possible before. Halley, because he was something of a workaholic, to put it mildly, looked back over cometary observations over the last two or three hundred years and wherever he possibly could, where there were sufficient observations, he worked out the orbits of about two dozen different comets. And he discovered that four of those comets actually seemed to have remarkably similar orbits. All four of them orbited in the same plane. All four of them came into the inner solar system from the same direction and left it in the same direction. And all four of them seemed to have this closest approach to the sun that was much the same in each case, and critically, the four of them were all about 76 years apart. He concluded that these four separate comets were in fact one and the same comet. So he made his famous prediction, and I'm using his actual words here, I dare venture to foretell that it the comet will return again in the year 1758. And sure enough, it did return in 1758. It was first seen by an amateur German astronomer on Christmas Day 1758. And ever since then it has been known as Halley's Comet. And quite rightly too, if Halley had had the idea of extending backwards his 76 year series, which he may have done, but we don't actually have any historical records to show that he did, he would have realized that his comet made an appearance in 1066. And lo and behold, if you look at the Bayeux Tapestry, somewhere along that tapestry there is an image of, of Halley's Comet. And I understand that the biotapestry is going to be on display at the British Museum this September onwards. So if any of Your listeners do go along to see it, please can they make a point of looking out for this image of Halley's Comet.
- [43:37]
Professor Susannah Lipscomb
Foreign.
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- [44:38]
Professor Susannah Lipscomb
It's a wonderful story. What I want to know is how did this discovery, this prediction, change the way that comets were seen culturally? Because for so much of the 16th century, they seem to be ominous portents of disaster. Does Halley's discovery reshape that way of thinking?
- [45:04]
David K Love
Yes, absolutely it did. You're quite right. Up until that time, comets were seen as things that foretold doom and destruction in some way. I remember doing Julius Caesar as my Shakespeare set book for O level. And there's that wonderful quote by Calpurnia, when beggars die, there are no comets seen. The heavens themselves blaze forth the death of princes. And that, of course, was written by Shakespeare, who was in much the same period. And that is a very good summary of the way a lot of people thought about comets, that they were not things for scientific study. They were, you know, they were foretelling doom and destruction in some way. Now, that attitude was beginning to change in Halley's time, but he actually demonstrated that these things could be studied scientifically. And if ever they did appear immediately before some terrible disaster, this was just coincidence. And an awful lot of the time they appeared and there were no associated disasters. So, yes, he was one of the people who brought about the change to a more scientific view of comets. Definitely. And he also, in doing that, he made it far more difficult for anybody to say that Principia was not a valid way of looking at the universe, because Halley had used the results in Principia to predict the return of the comet and nobody else had ever managed to do that before. Yeah, that was a Big sea change in attitude towards comets that Halley was indeed partly responsible for.
- [46:59]
Professor Susannah Lipscomb
Now, that's not his only achievement. They weren't all he did. Can you tell me about the worst naval disaster in British history and how Halley was not listened to on that occasion?
- [47:16]
David K Love
Yeah. This disaster, which was pretty dreadful, could have been avoided if Halley's advice had been taken, which it wasn't. But this concerns poor old Admiral Sir Cloudesley Shovel.
- [47:30]
Professor Susannah Lipscomb
What a name.
- [47:31]
David K Love
Yeah. Isn't it a lovely name? Yes. He was in charge of a fleet of 20 or so ships conducting a military campaign somewhere in the Mediterranean. And the campaign came to an end and it was time to go back home. So they sailed out of the Mediterranean into the Atlantic and started sailing north. And on the 18th of October, 1707, they turned eastwards in order to sail up the English Channel and back home to Portsmouth. And then the disaster struck on the 22nd of October. And that's in terms of the Julian calendar. You can make it more vivid by pointing out that under the Gregorian calendar, which England was frankly, pathetically slow to take up, that would have been the 1st or 2nd of November, which gives you an indication that they were now entering very much a wintry period and the weather was becoming a lot worse. And in fact, on 22 October, the sky had been covered with thick clouds all day, along with persistent drizzle and strong winds. But the thick clouds meant that it was impossible to get a decent value for their latitude, which was particularly important. They also, for the reasons discussed, weren't able to get their longitude with any accuracy. But worse than that, they were dealing with dangerously inaccurate charts, because all the charts at the time showed the Scilly Isles some considerably way to the north, 10 miles or even 20 miles to the north of where the Scilly Isles actually were. Just in case anyone doesn't know, the Scilly Isles are this group of islands off the southwest coast of Cornwall. And not only that, it's probable that the compasses on board ship weren't working terribly well, partly because an examination of compasses subsequently to the disaster by the Admiralty discovered that a full 80% of their compasses weren't working terribly well, largely because of rust, but they may also have been getting inaccurate readings on the compasses anyway because of this thing called compass variation. What you want to know from a compass is the direction of true north. And of course, what you actually get is magnetic north. And in that particular part of the world at that time, there was a difference of something like seven degrees between the two. So if they didn't know that and they were dealing with dodgy compasses, their idea of the direction of north wouldn't have been terribly good. It couldn't have been worse. They didn't know their latitude very well, they didn't know their longitude very well. They had inaccurate charts, the compasses probably weren't working well. The weather was lousy and it was dark. If Cloudesley Shovel had had any sense, he would have said, let's drop anchor here and wait until the weather gets a bit better. But they for some reason ploughed on and the result was that they hit the Gylstone Rocks, which is a group of rocks off the island of St. Agnes, which is one of the larger of the Scilly Isles. And the first four ships were went down with the loss of, depending on whose figures you believe, something between 1300 men and 2000 men. So an enormous cost in terms of life. One person survived. One person managed to cling to a rock all night and was rescued the next day. But Cloudsley Shovel was amongst those who drowned. He and a group of senior officers apparently tried to get away in a rowing boat, but at some stage the rowing boat must have overturned and they were all drowned because their bodies were found on the beach at St. Mary's island, quite some way away the following day. So overall, an absolutely massive disaster, which perhaps might have been avoided if people had taken notice of Halley. Now, Halley had been up and down the English Channel on a number of occasions and he was never one just to sit around on the deck sunning himself. He had obviously taken the opportunity on at least one occasion to measure the most southerly extent of the Scilly Isles. And he discovered that the most southerly extent was at 49 degrees and 50 minutes, which was, as I implied earlier, 10 miles or 20 miles south of what all the charts at the time said. So he recommended to anyone who would listen, and this was all published in a paper for the Royal Society, that in sailing along the English Channel, nobody should go north of 49 degrees and 40 minutes. So giving them extra latitude in case of error. But either Cloudesley Shovel had never heard that advice or if he did, he decided to ignore it. I just get the impression that if Halley had been in charge instead of Cloudesley Shovel, the accident would never have happened. And, yes, that is the sorry story of Sir Cloudesley Shovel.
- [53:15]
Professor Susannah Lipscomb
Thank you for sharing it with us. Goodness me. I'd like to ask you a little bit about Halley's relationship with some of the other people we call scientists at the time. You alluded earlier to the fact that it was a period in which he and Flamsteed were great friends, as if that didn't continue for all time. So were there rivalries or collaborations with people like Flamsteed and Hooke in general?
- [53:42]
David K Love
It's very true to say that Halley was well liked by most people. He seems to have had that warm personality and a genuine liking for other people and a genuine interest in other people, which most people like that, and therefore most people liked him. The one huge exception was John Flamsteed. Now, they started off as good friends when Halley was an eager young man who could help Flamsteed out with his observations. And the relationship seems to have soured in the 1680s. Nobody knows exactly why, but at least part of the reason may well have been that Flamsteed suffered from ill health a lot, whereas Halley hardly had a day's illness in his whole life. And this must have grated a little bit, I think, with Flamsteed. Flamsteed also was narrowly religious, in. In the worst sense of the word, whereas Halley was known for his liberal, skeptical attitudes towards religion, and Flamsteed would not have liked that at all. So a combination of those sorts of factors meant that Flamsteed was forever writing rude letters to people saying what an awful man Halley was. And Halley tried to come to some sort of reconciliation with Flamsteed, but they never really succeeded. And I think Flamsteed, towards the end of his life, he died in 1719. Still, as the first Astronomer Royal, he would have been rather upset at knowing that almost certainly Halley would be asked to take over as the second Astronomer Royal, as indeed he was. He must have felt quite bitter about that. But there we are. Other people generally got on well with, for example, Isaac Newton, even though Newton tended to dislike people the least little thing, somehow their relationship was very good practically all the time.
- [55:50]
Professor Susannah Lipscomb
So to end, then, can you give me a sense of how Halle was received at the time, whether his ideas were popular or controversial, and also just hint at some of the other topics that he published or wrote about, because we know him for his comet, but what else should we know of him?
- [56:16]
David K Love
Oh, he published numerous papers for the Royal Society on all sorts of things, and it's a great shame we don't have the time to spend another couple of hours going through them. One thing that ought to be mentioned is that he was responsible for proposing a method for working out the absolute size of the solar system. Now, up until then, we hadn't really been at all certain of, for example, the Earth sun distance. From the time of Copernicus, we knew relative distances within the solar system. So if you took the Earth sun average distance as one unit, whatever that unit actually is, nobody really knew then that meant that the distance between the sun and Mars was 1.52 units. That's just a matter of geometry. And the distance between the sun and Venus was 0.72 units. Again, just a matter of geometry. But nobody knew with any certainty what the Earth sun distance actually was. Now, we probably haven't got time to go into it, but Halley realized that you could use transits of the planet Venus across the face of the sun to measure, in effect, the distance between the Earth and Venus and therefore the distance between the Earth and the Sun. Unfortunately, these transits don't come up very often. They come up in pairs eight years apart, and those pairs are separated by over 100 years. But he knew that the next pair was coming up in 1761 and 1769. So he set out in a very detailed paper in Latin, so that it would have the maximum impact throughout Europe, because everyone would understand the Latin. He set out how, if you had lots of observers all over the surface of the Earth making measurements of the time that the transit started, local time, and the time that it ended, then you could use a whole load of complicated mathematics to work out the Earth Venus distance and thence the Earth sun distance. And people took him at his word. And even though he was dead by then, he died in 1742. Come 1761 and 1769, people all over Europe ended up going all over the globe in order to observe these transits of Venus. And we did end up, as a result, with a much more accurate measure of the Earth's sun distance for the first time. So Halley is responsible for that. And that's yet another thing to his credit. As for what you were asking about, how did people in general find Halley? That's a bit difficult to know. I think in educated circles he was very highly regarded. Beyond that, it's a bit difficult to know. We do know that he took an interest in what the uneducated masses thought of scientific things, because, for example, in 1715, there was a total eclipse of the sun where the Moon's shadow actually passed right over the middle of England and right through London. And Halley produced a map showing in advance where this eclipse would be seen as being total from and circulated it widely because he was a bit concerned that rather as with comets, a lot of people would regard this total eclipse of the sun as some sort of an indication of some terrible doom to come. I think George the First had recently come to the throne and he was concerned that people might think that something terrible was going to happen to George I. And in this paper he was trying to explain that, no, this is a purely natural phenomenon. It occurs somewhere every year or two, somewhere over the Earth's surface, and this time it just happens to be happening in England and it's nothing to worry about.
- [60:29]
Professor Susannah Lipscomb
Well, David Love, thank you so much for a wonderfully clear exposition of Halley's ideas, of Newton's ideas, of the nature of astronomy itself in the 17th and 18th centuries. It has been an absolute delight and you've made absolutely transparent the reason for Halley's enduring significance. And I'm very grateful for you for taking the time to come on to explain that all to us.
- [60:59]
David K Love
Thank you very much. It's been a pleasure to come.
- [61:03]
Professor Susannah Lipscomb
Thank you for listening to this episode of Not Just the Tudors From History Hit. Thank you also to my researcher Max Wintool, my producer Rob Weinberg, and to Amy Haddow, who edited this episode. We are always eager to hear from you, including receiving your brilliant ideas for subjects we can cover. So do drop us a line and not just the Tudors historyhit.com and I look forward to joining you again for another episode. Next time on Not Just the Tutorial from History Hit.
- [61:39]
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