Heroes of the Age of Reason
It’s hard to avoid the Universe these days. It’s everywhere—if you’ll pardon the pun. Newspapers and TV news bulletins feature the latest images from the Hubble Space Telescope and the exploits of robotic deep-space probes. Astronomy magazines vie for your attention in the local newsagent’s (usually among the New Age and astrology exotica—but at least they’re there). Radio stations run stargazing segments from both professional and amateur astronomers. And stunning TV documentaries wow you with the wonders of the Universe. It’s all terrific—and long may it continue.
It was not ever thus, however. Back in the 1950s, in drab, post-war Britain, you had to look hard in a library to find a book on astronomy, let alone see any media coverage. There was none of the exciting in-your-face science that we are so used to today. And absolutely nothing was in colour—with the single exception of the Eagle comic and its science-fiction hero, Dan Dare (whose exploits in space contained a good measure of real science, thanks to the expertise of his gifted creator, the late Frank Hampson).
So you can probably appreciate the inspirational effect on young would-be scientists that a colourful and authoritative production on astronomy would have had when it appeared. But you may be hard pressed to imagine where you would have found it. A book? A magazine? Neither. It was in—wait for it—packets of tea. Tea? To be precise, it was in Brooke Bond Choicest, PG Tips or Edglets, leaf teas all, with not a teabag to be found. It’s hard to imagine anything more eccentrically British than astronomy with a cup of tea thrown in. Or, rather, poured in.
This curious venture came about when the Brooke Bond Tea company, convinced of the sales potential of collectable cards in its products, commissioned a series of 50 informative picture cards on astronomy called ‘Out into Space’. A quarter of a century earlier, cigarette companies had pioneered the card-collecting craze, but astronomy tea cards were a new thing. The ploy worked, and the cards were avidly collected by the nation’s ten-year-olds. Quite a few of today’s best-known astronomers had their careers decided by Brooke Bond’s seductive artwork. One such was David Allen, a truly gifted astronomer and science communicator at the former Anglo-Australian Observatory in Sydney, who sadly died in 1994. Towards the end of his life, David spoke with affection of the tea cards that had inspired him as a boy in Manchester. And you may not be surprised to hear that there’s a bookcase close to my keyboard that contains a complete set of the cards, secure in the album that could be bought ‘from your grocer, price sixpence’ to house them. Yes, they inspired me, too, and are today a treasured keepsake.
Each card in the series has colour artwork on one side and an explanatory text on the other, printed, of necessity, in a microscopic type. The identity of their author is not recorded, but they do carry the blessing of a prominent astronomer, the late Alan Hunter, whose affiliation is noted on the cards only as secretary of the Royal Astronomical Society, although he became acting director of the Royal Greenwich Observatory in the mid-1970s. By then, that venerable institution was no longer in Greenwich, having long before relocated to the darker skies of Sussex. I remember Hunter masterminding its 300th birthday celebrations, in 1975, with flair and skill, when I was a youthful staff member there. In his role as boss of the observatory, Hunter was following in the hallowed footsteps of John Flamsteed and ten subsequent astronomers royal. In 1972, however, the positions of astronomer royal and director of the observatory had been separated. It was the beginning of the end—a little more than a quarter of a century later, the Royal Greenwich Observatory ceased to exist.
A browse through the tea cards with today’s hindsight is an interesting exercise. You get the impression of an arbitrary mishmash of rather old-fashioned astronomy mainly highlighting the planets and stars. Galaxies—the immense objects that we now know contain hundreds of billions of stars—are called ‘spiral nebulae’, a term that was already out of date by 1930. More recent headlinegrabbers, like quasars, black holes and neutron stars, were unknown, of course. Apart from one picture of a radio telescope, the cards could have been produced a century ago, and the fact that Pluto barely rates a mention has less to do with our modern understanding of its place in the Solar System than the cards’ author not having got used to its presence in the first place.
Several cards cover basic astronomical phenomena like the seasons, eclipses and tides, although the poor old Moon receives only a background sketch in the album. The planets each have a card of their own, and there are no fewer than three describing the signs of the zodiac. Another three depict a ragbag collection of astronomical instruments: the radio telescope, a glass prism for analysing starlight and a sixteenth-century astrolabe—in that order.
The bulk of the set, however, is devoted to pictures and descriptions of the constellations. Twenty-two cards cover an odd mixture that leaves you wondering quite what the selection criteria were. Orion, for example—the brightest and most recognisable constellation in the entire sky—didn’t make it. In spite of that, it is in the constellations that the real charm of the cards emerges. Colourful star maps with outline figures of their mythical counterparts set against a midnight-blue sky evoke something of the magical appeal of simple, naked-eye stargazing. They give the cards the air of belonging to the Age of Enlightenment, when science was just beginning to disentangle itself from the beliefs and superstitions of former times.
Quaint though they seem today, the tea cards were truly the best thing around for a 1950s Pommie youngster interested in astronomy. All the coolest kids in school had them, and parents went frantic buying up packets of tea, trying to find the last few missing cards. But the cards also had an interesting side-effect—for me, at least. To this day, I can’t smell the contents of a packet of tea without getting a strange feeling that there’s something exciting hidden at the bottom of it. I wonder if anyone else has experienced that sort of thing? While you’re thinking about it, I’ll just go and put the kettle on.
IN THE FACE OF THE SUN
The United Kingdom, of course, is a Mecca for astronomy history nerds. In many respects it is where telescopic astronomy came of age, following its birth in the hands of Galileo and his immediate successors. Early discoveries by Continental astronomers during the second half of the seventeenth century, such as cloud belts on the giant planet Jupiter and the misty patch of light we now know as the Andromeda Galaxy (discovered by Neapolitan and German astronomers respectively), led to significant advances in our understanding of the heavens. Prominent among these astronomers were Johannes Hevelius, Christiaan Huygens and Giovanni Domenico Cassini. A Polish brewer, a Dutch nobleman and an Italian working in Paris—it sounds like the start of a bad joke. But British telescopic astronomy was quick off the mark, with a fellow called Thomas Harriot sketching the lunar surface from London as early as July 1609, months before Galileo had perfected his own telescope.
Even more spectacular—albeit pitifully brief—was the career of a brilliant young Lancastrian named Jeremiah Horrocks. The son of a Liverpool watchmaker, Horrocks was born in 1618 and entered Cambridge University fourteen years later. There, his youthful interest in astronomy flourished, and he developed a particular enthusiasm for the work of the great German mathematician Johannes Kepler, then only recently deceased. Although a great admirer of Kepler, Horrocks realised there were gaps in the great man’s understanding of the mechanisms of the Solar System. In particular, the younger man made significant strides towards an understanding of the role of gravity a decade before gravity’s greatest exponent, Isaac Newton, entered the world.
To Horrocks goes the credit for being the first person to realise that the Moon, like the planets, has an orbit that is not circular but slightly elongated into an elliptical shape. His careful observations and accurate computations even allowed him to estimate the amount of that elongation—a tricky operation from our vantage point at the centre of the Moon’s orbit. He also recognised that the Sun influences the direction in which this elongation lies. But Horrocks’ greatest triumph came in 1639, when he was only 21. By then, he was living in the Lancashire village of Hoole, working not as the curate of the local church, as is often stated, but in some unknown occupation. Horrocks’ modern-day biographer, Peter Aughton, has suggested that his most likely position was tutor to the children of a wealthy local family. Whatever his job, Horrocks had time to pursue his astronomical work, and he became interested in an issue that had intrigued Kepler—the passage of Venus across the disc of the Sun. We now know that these events—transits of Venus—occur in pairs separated by eight years, with the intervening gaps alternating between 105.5 and 121.5 years, making a 243-year repeating pattern. The transits always occur in June or December (hence the half-years), and the early 21st century saw millions flocking to the world’s observatories to witness the June transits of 2004 and 2012. With smartphone apps available to record it, the 2012 transit became a mass media event. If you missed it, your next opportunity won’t be until December 2117. By then, you may well have lost interest.
Horrocks knew that Kepler had predicted the occurrence of a transit of Venus in 1631 but had died the year before the event, and that he had also said there wouldn’t be one in 1639. But Horrocks guessed that the transits always occurred in pairs, and he began to make careful observations of Venus as it moved slowly through the sky towards its conjunction with the Sun during 1639. From his measurements, he calculated that the planet would, indeed, pass between the Earth and the Sun on 24 November—as reckoned in the Julian, or Old Style, calendar, still in use in Britain at the time. (Despite having long been superseded throughout much of Europe by today’s Gregorian calendar, the Julian calendar was current in Britain until 1752. Well, what else would you expect?) The date of the transit in the Gregorian, or New Style, calendar was 4 December. Either way, it was a Sunday.
Forewarning a friend named William Crabtree of the impending transit, Horrocks made preparations to observe it by projecting the Sun’s image onto a screen with his telescope, thus avoiding the need to look directly at the Sun through it—which is always dangerous. Crabtree lived some distance away, near Manchester, but had his own telescope, so he, too, set it up for projection. The transit was predicted to begin late in the afternoon, with the Sun low on the horizon on that short winter’s day. Just before the due time, Horrocks was called away for some reason—possibly a church service—but when he returned, the small black disc of Venus was clearly visible on the Sun’s image. He was able to record its slow passage across the solar disc for only a short time before the Sun set, but he was absolutely delighted. That delight was well founded—he had become the first person ever to witness such an event by using the newly invented telescope, and he had correctly predicted its occurrence himself. Crabtree, too, was successful, but only by dint of a break in the clouds just before sunset.
The significance of this for astronomy was in demonstrating the effectiveness of careful observation combined with refined calculation. All done by hand, of course—there were no calculators of any kind in those days. It improved our understanding of the orbit of Venus and, along with other measurements, led Horrocks to conclude (correctly) that the Solar System was much, much bigger than anyone had guessed. It was another half-century, however, before Edmond Halley (of comet fame) presented a scholarly paper to the Royal Society of London on the idea that Venus transits could be used to gauge the Earth’s distance from the Sun. This eventually created the scientific imperative that drove Captain James Cook to Tahiti in 1769—and on to New South Wales.
What became of Jeremiah Horrocks? A few months after the transit, he returned to his family home, at Toxteth—today a troubled inner-city suburb of Liver pool, but then a nearby village. There, he further developed his astronomical theories, corresponding regularly with Crabtree and a handful of other astronomers in the north of England. Notable among them was a Yorkshireman, William Gascoigne, who had invented a clever device that allowed telescopes to be used for accurately measuring the separation of close pairs of objects such as double stars.
One might imagine that this cluster of bright young scientists could have become the nucleus of a learned society—a forerunner, perhaps, of the Royal Society, which came into being two decades later, in 1660. But it was not to be. On 3 January 1641, little more than a year after the transit of Venus, Horrocks died, at the age of 22. We don’t know the cause of his death; Aughton suggests a heart problem but admits this is only a guess based on the lack of any other evidence. Robbed of the shining star of their little group, Crabtree and the others were heartbroken. They kept in touch with each other and endeavoured to gather together Horrocks’ papers and letters.
But even worse events were about to befall them. Political and religious unrest had been smouldering throughout Britain during the 1630s, and, finally, in 1642, the nation exploded into civil war. The deep divisions that had long been growing cut through national and local boundaries, and through the educational and religious establishments, and even separated friends and families. Horrific battles followed, between the Royalist supporters of the monarchy, in the person of King Charles I, and the Parliamentarians, under Thomas Fairfax and Oliver Cromwell. They were the most brutal ever seen on British soil, inflicting terrible casualties, along with widespread looting and destruction. The Battle of Marston Moor, near York, on 2 July 1644, was especially punishing for the fledgling northern-English scientific community, most of whose members had Royalist sympathies. In short, the little group was decimated. Crabtree died after the battle, probably as a result of injuries sustained in it. Other Royalist friends fell, and, while Gascoigne survived Marston Moor, he died early in 1655, at Melton Mowbray. He was 24.
The civil war culminated, in 1649, with the defeat of the Royalists and the establishment of a republic, whose first act was the public execution of Charles I. Thus, Britain entered the puritanical era of the Commonwealth, in which scientific endeavour, like most other intellectual activities, was suppressed. With Horrocks and so many of his contemporaries gone, there was every chance that his work would be lost completely to posterity.
That, however, was not what transpired. Slowly at first, but with gathering momentum, the climate changed. With the death of Oliver Cromwell, in 1658, and the nation weary of puritanical impositions, the first steps were taken towards constitutional modifications that would allow the monarchy to be restored. They culminated, on 23 April 1661, in the coronation of Charles II. By then, men of science had again begun to gather. Indeed, on the very day of the coronation, a small group of astronomers, including the great Christiaan Huygens, assembled in London to observe a transit of the planet Mercury across the Sun’s disc—a more frequent and less significant event than a Venus transit. In the early years of the Enlightenment, Charles II became a staunch supporter of cultural advancement and bestowed his patronage on the infant Royal Society in 1662.
It was that learned body which eventually restored Jeremiah Horrocks to his rightful place in British astronomy, although, curiously, the society was not the first to recognise his achievements. In the same year that it had received its royal charter, the Polish astronomer Johannes Hevelius published a manuscript written by Horrocks with the title Venus in the Face of the Sun. It was a detailed description of Horrocks’ observations of the Venus transit and the calculations involved—characteristically enlivened with some of his own poetry. How the manuscript reached Hevelius a generation after Horrocks’ death is an intriguing story in itself, especially since all the circumstances had seemed destined to condemn the work to oblivion. In fact, an undergraduate friend of Horrocks’, John Worthington, initiated the rescue of his papers through his own recollections of the young astronomer’s pre-war activities. With the evident brilliance of this unknown British scientist brought decisively to their attention, the members of the Royal Society resolved to publish all his surviving work. Despite the turmoil resulting from London’s double whammy of the plague epidemic of 1665 and great fire of 1666, the society issued Horrocks’ complete Posthumous Works in 1672, with the enthusiastic support of a young John Flamsteed, among others.
At last, the writings of the man who has since been called the ‘father of British astronomy’ became accessible to a wide readership. They were greeted with enthusiasm throughout the scientific world. And we can only wonder what the course of science might have been had this astonishing figure survived beyond the tender age of 22. It’s no exaggeration to say that the greatest name in British science today could easily have been Jeremiah Horrocks instead of Isaac Newton.
THE AGE OF UNREASON
Not surprisingly, you would look in vain for Horrocks among the tea cards. More unexpectedly, you’d also look in vain for Newton. But at least the great man does figure among the background sketches decorating the album. He figures twice, in fact. On the first page there is a poor likeness of the youthful Newton, with a caption mentioning his discovery of the law of gravitation. Further along there’s a rather more creditable drawing of the stumpy little telescope he made in 1668, usually taken to be the first to use a mirror rather than a lens to form the image. In that regard, Newton is often hailed as the ‘father of the reflecting telescope’. But that paternity could be in doubt.
In Newton’s time, telescopes for astronomy were like the old-fashioned draw-tube telescopes we’re all familiar with today: a long tube with a glass lens at each end, and maybe one or two inside as well. In the quest for a better view, however, these telescopes had been taken to extremes, becoming steadily longer throughout the seventeenth century. The reason for this lay in a fundamental flaw in all early refracting telescopes. They suffered from chromatic aberration, a colourful defect resulting from the front lens splitting light into unwanted rainbow hues. This problem was eventually solved by combining lenses of different glasses, but in Newton’s day the only known remedy was to make telescopes long and thin—and the longer they got, the more unwieldy they became.
Ridiculously long telescopes dominated the astronomy of the time, and Christiaan Huygens was one of the chief offenders. Another was Johannes Hevelius, who built a series of instruments that culminated, in about 1670, in one whose length was no less than 46 metres. In its construction, this staggering contraption had more in common with the rigging of a sailing ship than an optical instrument. From a mast 27 metres high, the telescope’s ‘tube’ of planks was suspended by ropes and pulleys. It is easy to imagine the chaos that would have faced anyone trying to observe with it on a dark night. A large crew of assistants was required, and any breeze or sudden movement would have set the tube quivering uncontrollably.
Considered against this backdrop, it is easy to understand why there was a growing imperative to devise telescopes that would use mirrors rather than lenses. With a mirror, light simply bounces off the front surface and therefore does not disperse into an unwanted rainbow. But, while optical technology could produce adequate lenses by the early 1600s—albeit with the defect of chromatic aberration—it was another 60 years before opticians learned the art of making suitable mirrors. Few of those opticians would have been aware that it’s actually the laws of physics that make it so much harder to create an accurate reflecting surface than the equivalent lens surface.
The accepted wisdom is that the first person to succeed in this was Isaac Newton in 1668, by dint of careful experimentation in mirror polishing together with a sound theoretical understanding of both the physics of reflective surfaces and the ideal layout for the optical components. That much is certainly true—the arrangement he proposed is still the most common form of reflecting telescope in use by amateur astronomers. It’s no accident that it is known as a Newtonian telescope.
But, up in Scotland, there was a man a little older than Newton who had, before this, arrived at a telescope design of his own and had made a brave attempt to turn it into reality. This fellow was James Gregory, a gifted Aberdeenshire mathematician who had published the design in his book The Advance of Optics early in 1663, along with a discussion of the relative merits of telescopes using only mirrors or only lenses. Gregory’s design used a combination of both but required two accurately manufactured dished mirrors in order to work properly. Of unequal diameters and curvatures, these were referred to as the ‘primary’ and ‘secondary’ mirrors of the telescope, the primary being the larger (and shallower) of the two.
Gregory was nowhere near as practical a man as Newton, so, on a trip to London late in 1662 in connection with the publication of The Advance of Optics, he had engaged the services of an optician called Richard Reeve and his assistant Christopher Cock to grind and polish the metal mirrors. (At that time, mirrors were made of a brittle alloy called ‘speculum metal’ rather than glass.) Reeve (whose name is variously spelled Rive, Reive, Rives or Reeves) was one of the most accomplished optical workers of the day and a thoroughly interesting character in his own right. Not long after his work with Gregory, he slew his wife—possibly unintentionally—but received a royal pardon on account of his optical skills. And, indeed, it seems that the only thing that stopped him producing a fully working reflecting telescope for Gregory early in 1663 was the Scotsman’s haste to be off on a sabbatical tour of the Continent. This is revealed in a letter written on 23 September 1672 by Gregory (who was by then regius professor of mathematics at the University of St Andrews) to John Collins, a prominent fellow of the Royal Society.
As for my experiment with Mr Rives, he could not polish the large concave upon the tool . . . Upon this account, & being about to go abroad; I thought it not worth the pains to trouble myself anie further with it, so that the tube was never made; yet I made some tryals both with a litle concave & convex speculum; which wer but rude, seing I had but transient views of the object.
This suggests that Gregory came close to building the world’s first reflecting telescope five years before Newton did. While Reeve had not managed to polish the primary mirror to Gregory’s satisfaction, it had been good enough to provide ‘transient views’ when tested with the secondary one.
What is even more notable from the letter is that Gregory was quite clear that he used both concave and convex secondary (‘litle’) mirrors in separate tests—that is, mirrors that are dished inwards and outwards respectively. The significance of this is that today a reflecting telescope design that uses a combination of two unequal concave mirrors is called a Gregorian telescope, but one that uses a large concave mirror with a small convex mirror—as also described by Gregory—is called a Cassegrain telescope.
Gregorian is obviously from Gregory, but where does the name Cassegrain come from? There are some Australian astronomers who are convinced that it’s named after a vineyard near the mouth of the Hastings River, in New South Wales, but I suspect they are suffering delusions induced by some of that same establishment’s fine products. Cassegrain was, of course, a person—a seventeenth-century mathematician who lived in France and who probably wasn’t averse to a drop of sauvignon blanc himself. That much is well known, but no sooner did Cassegrain pop up in the historical record than he promptly dropped out of it again, vanishing almost without trace. In fact, even his original appearance in the annals of the telescope was at second hand, for his idea had been put forward on his behalf, in 1672, by another Frenchman, Henri de Bercé.
To understand why Cassegrain performed this astonishingly successful disappearing act, you have to look no further than Newton’s caustic response to the Frenchman’s invention in a letter he wrote to Henry Oldenburg, secretary of the Royal Society, on 4 May 1672. This was published in the Philosophical Transactions (the society’s journal) and, no doubt, quickly found its way to France. Basically, it poured scorn on the idea, suggesting that Cassegrain should try manufacturing one of the telescopes before he made such announcements.
I could wish therefore M. Cassegraine had tryed his designe before he divulged it; But if, for further satisfaction, he please hereafter to try it, I beleive the successe will informe him, that such projects are of little moment till they be put in practise.
But, in later correspondence, it’s also evident that Newton believed Gregory must have been fully appraised of the Cassegrain design when he wrote The Advance of Optics, almost a decade earlier. As Newton made clear in a letter to Collins dated 10 December 1672, Cassegrain’s ‘invention’ was not his to invent—Gregory had already done it.
I doubt not but when he [Gregory] wrote his Optica promota [The Advance of Optics] he could have described more fashions then [sic] one of these Telescopes & perhaps have run through all the possible cases of them if he had then thought it worth his paines. Because M. Cassegrain propounded his supposed invention pompously, as if the main business was in the contrivance of these instruments I thought fit to signify that that was none of his contrivance, nor so advantageous as he imagined.
It would be a bold individual indeed who would take on Isaac Newton, given his mushrooming reputation, and Cassegrain did what most of us would have done and shrank back into obscurity. So complete was his disappearance that it was only in 1997 that French astronomers were able to identify him as Laurent Cassegrain, who was born in Chartres, in the Eure-et-Loir département in northern France, in about 1629 and died in nearby Chaudon on 31 August 1693.
Despite these remarkable events, Cassegrain’s name is still attached to the most common arrangement of mirrors found in the largest observatory telescopes. Gregory’s contribution has slipped out of prominence, and that has happened with much of his work. In mathematics, Gregory was probably the equal of Newton and, under different circumstances, might have gone on to great things. But his unassuming personality meant that he was always in awe of Newton and often failed to publish his own ideas as a consequence. And, unlike Newton, who lived to the age of 84, Gregory died while still a young man, suffering a stroke when he was 36, only a year after he had taken up the chair of mathematics at the University of Edinburgh, in October 1674.
On one matter, Newton and Gregory were in complete agreement: their regard for the late Jeremiah Horrocks following the publication of his Posthumous Works in 1672. Each of the men wrote to John Collins about the book. Newton said, ‘I am very glad that . . . the world will enjoy the writings of the excellent Astronomers Mr Horrox & Hevelius,’ while Gregory was characteristically more sympathetic:
I received . . . Horrocci posthuma [Posthumous Works], for which I must aknowledge my self exceedinglie engaged to you: I have perused him & am satisfied with him beyond measure; it was a great loss that he dyed so young; many naughtie fellows live till 80.
Ah, yes. Even today you’ve got to watch out for those naughty 80-year-olds.
With both Horrocks and Gregory fated to die at a young age, it was left to Newton to soar in his thinking regarding the big questions of the mechanisms of the Solar System. And, as the tea card album sketch hints, this culminated in his work on gravitation.
We know that Newton’s ideas on gravity date from an enforced stay at his home in Lincolnshire in 1665, when the University of Cambridge had closed its doors to prevent an outbreak of the plague that was devastating London’s population. There, he linked the downward force pulling an apple to the ground with the force that holds the Moon in its orbit. The mathematical relationship governing the nature of that force gradually took shape in his mind, and, by 1684, when he received an enthusiastic visit in Cambridge from Edmond Halley, he had formulated its exact form.
Halley facilitated the publication of this work, along with Newton’s theories of the motion of objects through space and their motion through a dense medium such as water. Together, the various chapters formed The Mathematical Principles of Natural Philosophy (Philosophiae naturalis principia mathematica), published in 1687 and perhaps the most far-reaching scientific book ever written. Known today simply as the Principia, this extraordinary work not only explained the motions of planets and satellites as deduced by Kepler but extended the study to projectiles shot from guns, pendulums, comets, tides and the more subtle motions of the Earth and Moon. With marvellous insight, Newton’s conclusions ranged from the simple idea that all heavenly bodies are in a state of mutual attraction to the unbelievable notion that artificial satellites could be made to orbit our planet. The Principia was earth-shattering in its influence, solving most of the problems then current in astronomy and setting the course of scientific research for the next two centuries. It was a very hard act to follow.
HALLOWED GROUND
Many of the places we have roamed through in this chapter were destinations for the Stargazer I tour in 2008. Central London was particularly memorable, not only for the Royal Society and the Monument to the Great Fire of London, but also because of an incident involving two of our party. As keen astronomers from the southern hemisphere, they were eager to use their portable telescopes to explore the sights of the northern sky and went off in search of somewhere shielded from the city’s lights. One of the royal parks seemed ideal for the task—but how were they to know that certain areas are out of bounds to the public after dark? They came close to being arrested for their late-night excursion and returned shamefaced to the hotel in double-quick time.
In fairness to their enthusiasm, the incident was not too different from an unexpected visit I had one night as a youngster when I was using a borrowed brass telescope on a tripod in the garden of my home in Yorkshire. The visitor was a large policeman, who was responding to a call from a neighbour about a suspicious-looking youth fooling around with a Second World War bazooka. Fortunately, I was able to reassure him that it wasn’t loaded. It’s the kind of thing that happens when you get into astronomy.
The Stargazers took in Yorkshire, too, with a brief stop in Leeds, not far from where William Gascoigne had lived, and the next day we embarked on a memorable visit to Isaac Newton’s Cambridge. At the Institute of Astronomy we were among friends, who happily showed us their treasures.
A particular highlight of the tour, however, was our homage to James Gregory in Scotland, with visits to both St Andrews and Edinburgh. The universities of those two ancient cities are where I was educated, so this was a trip close to my heart. At St Andrews we were privileged to receive a conducted tour by a good friend and former colleague, Andrew Collier Cameron, whose research speciality is the planets of other stars. We were able to see the north–south meridian line set into the floor of the Upper Hall of the old University Library by Gregory himself, when he used the room for astronomical observations in the early 1670s. His clock is also there, along with an iron bracket used to support his spindly refracting telescope in a south-facing window. The humble bracket had a narrow escape during the mid-2000s, when it was inadvertently consigned to a skip during renovations to the building.
At St Andrews, too, we were joined by the astronomer royal for Scotland, John Campbell Brown, of Glasgow University, who is a great supporter of science outreach activities and was happy to give us a unique talk in nearby Dunfermline, where my daughter and son-in-law owned a restaurant. His memorable after-dinner presentation was illustrated not with PowerPoint slides but with magic tricks. Now there’s a science communication skill I wish I could emulate.
The visit to Edinburgh was equally memorable. The Royal Observatory houses one of the jewels of the astronomical world, in the shape of the Crawford Library, a collection of rare books and manuscripts gifted to the observatory by the 26th Earl of Crawford in 1888. It is one of the most important collections in the world, and we were amazed at the generosity of the librarian Karen Moran in allowing us to handle first editions of Copernicus’ Revolutions, Newton’s Principia and the works of Tycho, Galileo, Kepler and Gregory—to name just a few. A couple of the tour participants had tears in their eyes as a result of this close encounter with some of the greatest works in the whole of science.
In Edinburgh there was a classic case of coals being taken to Newcastle, in the shape of a public lecture about the local hero, James Gregory, given by a visiting Australian scientist. I wonder who that could have been?
And then we went to Bath. Why Bath? It’s a beautiful city with architecture from the Georgian era of the eighteenth century and a heritage that goes back to Roman times, most of whose historic venues are within walking distance of one another. Notable attractions include the Roman baths and the Jane Austen Centre, and we were also able to take in the United Kingdom’s most famous megalithic site on the way there from London—the prehistoric grandeur of Stonehenge.
But our main reason for visiting Bath was that it was where Newton’s very hard act to follow was, well, followed. From 1766 to 1782, Bath was the home of William Herschel, truly one of the brightest stars in the history of astronomy. Variously described as the ‘greatest astronomer of all time’, the ‘greatest telescope-maker of all time’, the ‘father of galactic astronomy’ and the ‘father of infrared astronomy’—all with some justification—Herschel is a towering figure in science history. His career is all the more remarkable when one considers that it was, in fact, his second career, on which he did not embark until 1773, when he was 35 years old. Before that (and, indeed, for some years beyond), he was a professional musician.
It was in Bath where Herschel rocketed to fame, when he became the first person ever to discover a planet. The five naked-eye planets—Mercury, Venus, Mars, Jupiter and Saturn—have been known since antiquity, but, on 13 March 1781, by dint of careful observation with a homemade telescope, Herschel discovered another one. It’s well known that he wanted to call it Georgium sidus, the Georgian Star, in honour of the king, and that could be seen as a shrewd move to curry royal favour. Indeed, it was—and it did—but it was not Herschel’s fault that the seventh planet of the Solar System ended up with the mildly inappropriate name by which we know it today. That was the idea of one Johann Elert Bode, and even then he can’t really be blamed, as the name sounds absolutely fine in his native German.
Uranus was discovered from the garden of Herschel’s modest house in New King Street, Bath, which is today the Herschel Museum of Astronomy. It is also the place where he conceived the idea of developing monster telescopes to study the enigmatic misty patches that astronomers call ‘nebulae’, and, along the way, of course, to impress his monarch. Herschel recognised that ever-bigger mirrors would reveal fainter objects in ever-greater detail, and it became his unfulfilled quest to find out whether all nebulae were made of stars or whether some were made of something else. That quest eventually inspired the greatest reflecting telescopes of the nineteenth century. It was with these heady issues filling their minds that the Stargazer tourists made their pilgrimage to the Herschel Museum. If ever a group of enthusiasts trod upon hallowed ground, this was it.
UNSAFE PRACTICES
Despite his intellectual talents, his practical abilities and his general all-round competence, William Herschel had a few blind spots. One is in an area that we take infinitely more seriously today than he evidently did—to wit, occupational health and safety. Herschel’s behaviour in this regard was a complete disaster. But this is perhaps not surprising, since he was attempting to build the largest telescopes ever conceived using structural techniques that were rudimentary even by the standards of the late eighteenth century.
His most famous instruments are known by the lengths of their tubes—the Large Twenty-Foot (6.1 metres) of 1783, and the Forty-Foot (12.2 metres), completed six years later. These telescopes were built at Herschel’s later home in Slough, near Windsor. They were monumental timber structures carrying metal mirrors that, in the larger telescope at least, weighed a significant fraction of a tonne. The observing position on both was high on the rigging and very exposed. They were dangerous instruments to work with, and when the Large Twenty-Foot was blown over in a gale, in March 1784, it was only by chance that no one was injured. Herschel merely noted in his journal that, ‘fortunately, it is a cloudy evening so that I shall not lose time to repair the havock that has been made’.
Herschel’s sister, Caroline, an able and accomplished astronomer in her own right, was much more aware of the hazards surrounding the family business. ‘I could give a pretty long list of accidents which were near proving fatal to my brother as well as myself,’ she wrote late in her life. Indeed, she had first-hand experience of William’s neglect when, in the darkness of a winter’s night, she gashed her leg badly on an iron hook hidden in the snow. Likewise, a protruding bar on a telescope caused serious injury to an eminent visiting astronomer whom we met in Chapter 2—Giuseppe Piazzi, the discoverer of the first known asteroid.
Herschel himself experienced several heart-stopping moments, including one with his younger brother, Alexander, in 1807, when a beam supporting the 1-tonne mirror of the Forty-Foot broke as it was being removed from the telescope for its regular repolishing. Fortunately, it didn’t have far to fall onto its handling carriage, but Caroline noted with evident shock that ‘both my brothers had a narrow escape of being crushed to death’.
Perhaps the worst episode of all occurred 26 years earlier, however, when William was carrying out his first experiments in casting large telescope mirrors in his house in Bath. In August 1781, he tried to cast a mirror 90 centimetres in diameter for a proposed Thirty-Foot (9.1-metre) telescope. The experiment failed when a quarter of a tonne of molten metal poured with explosive violence out of a broken mould onto the stone floor of the basement workshop. Herschel and his workmen were lucky to escape with their lives, and the project was abandoned. Fortunately for astronomy, Herschel later managed to get the hang of this technique.
Perhaps it is churlish to accuse Herschel of neglecting safety standards when both his telescope making and his observing pushed back the frontiers of knowledge in ways that had never been seen before and have hardly been seen since. But it remains true that he was lucky—very lucky—that no one was killed as a result of his activities. Especially since the life most likely to have been lost was his own.
Before we move on from Herschel, there is one more story of unsafe practice on his part to be told, concerning risky behaviour of a different kind. The tale was uncovered a few years ago by the Cambridge-based Herschel specialist Michael Hoskin.
In 1757, as a nineteen-year-old musician, Herschel moved from his native Hanover to London. We are told in the history books that this was to pursue his ambitions as a composer, but it now seems there was rather more to it than that. The tale may even go some way towards explaining the zeal with which Herschel immersed himself in the culture of his adopted country, discarding the Hanoverian name of Wilhelm Friedrich to become the terribly British William Frederick.
We actually know a great deal about Herschel the musician, particularly since much of his music has survived and is today readily available in recordings by leading musicians. There’s no doubt that he was a composer of great talent, and if you want to acquire insight into his cheerful disposition you can hardly do better than listen to some of his organ works, as recorded, for example, by the modern-day French astronomer-musician Dominique Proust. Indeed, participants in the Stargazer II tour, in 2010, were delighted when Proust gave us a private recital at the church of Notre-Dame de l’Assomption in Meudon, near Paris, after showing us the highlights of the Meudon Observatory. Given the optimistic nature of Herschel’s music, it’s surprising to discover that his departure from Hanover took place in the midst of chaotic upheaval.
He had been born into a musical family, the son of an oboe-player in the Hanoverian Guards. In 1753 he followed his father and his older brother, Jacob, into the regimental band, but within a few years military responsibilities overtook musical ones. French ambitions against Hanover resulted in the defeat of the Guards at the Battle of Hastenbeck, in July 1757. William Herschel, then eighteen, was told by his father to hotfoot it home to escape the fighting. When he arrived in Hanover, however, his mother told him he would be far better off with his regiment, since a civil defence force was being mustered in town and he risked being conscripted into it. At least in the army he was officially a non-combatant. So back he went, stealing unnoticed to his post.
It’s a measure of the concern Herschel’s father had for his two sons that he then plotted to spirit them across the English Channel to escape the ongoing skirmishing with the French—who, by now, had occupied Hanover. This was not so much a problem for Jacob, whose musical talents had allowed him to revert to civilian status, but William was still in the army. So, late in 1757, the two brothers arrived safely in the United Kingdom, then ruled by the Hanoverian dynasty of the royal family. Back home, however, Herschel’s father was promptly arrested ‘by way of enforcing the return of the Deserter’, as Caroline put it in her autobiography, although it failed to have the desired effect. It was another two years before the Hanoverian troubles subsided, with the defeat of the French at the Battle of Minden, in August 1759. Jacob quickly returned home, but that option was not open to ‘the Deserter’, who elected to remain in the United Kingdom. It was not until 1762 that William Herschel received his discharge from the army—probably through Jacob’s influence—and was able to visit his native city once again.
Herschel might not have been happy to be labelled a ‘deserter’, but most of us would have done exactly the same thing in such circumstances. His father—entirely understandably—was the instigator of these events, and he paid the price with his detention. It’s easy to imagine that, had he not taken the course of action he did, his gifted son might have met an early end on the battlefields of Lower Saxony—and astronomy would have been immeasurably the poorer.
Perhaps the one hint of embarrassment on Herschel’s part, highlighted by Michael Hoskin, is that when he wrote of the events a quarter of a century later, Herschel was rather sparing with the truth. He explained that the war had made his situation in Hanover ‘very uncomfortable’, but also said that ‘the known encouragement given to Music in England determined me to try my fortune abroad & accordingly about the year 1759 I came to settle in this country’. Who can blame him for glossing over the details?
ULTIMATE JOURNEY?
As a study tour destination, Hanover has much to recommend it, and no doubt will figure in future science history trips. I’ve been there once, but it was under quite different circumstances from the relative calm of an astronomy tour. It was a mission—something that just had to be done. My brother, John, and I took our elderly Aunt Dorothy to Hanover on a brief summertime visit that, I guess, was our way of saying thank you for all the wonderful times she had given us decades before, when we were youngsters. It was a pilgrimage that had already been made by her father and sister, and we had wanted to ensure that she made it, too.
By then, though, Aunty Dot was seriously cantankerous, more than slightly incontinent and wont to chain-smoke her way through almost every waking moment. Her manner towards John and me was reminiscent of the way you’d deal with a pair of badly behaved ten-year-olds, despite the fact that we were both in our fifties and had grown-up kids of our own. But we coped with all that and tried to give her the best experience we could.
Our destination was in a place called Harenberg, on the western outskirts of Hanover, and, as we approached through open countryside along the Harenberger Meile, we could see our objective off to the right. On a gentle south-facing slope, sparkling in the sunlight after a passing shower, stood row upon row of identical white headstones. John parked the car, and we walked among them, reading the inscriptions as we went. The most sobering aspect was the age of the brave young men whose headstones they were. Most had been between 19 and 22, barely in their prime, as they took to the skies in their thousands to inflict a mortal blow on a psychopathic regime. The neat rows stood in stark contrast to the chaos that would have surrounded those Allied airmen as they fell. Gathered from all over Lower Saxony, their bodies suffered similarly horrific injuries to those of the fallen of Marston Moor, exactly 300 years before. It made me wonder what we had learned. Of course, we were looking for one name in particular. And, yes, we found it.