Eighteenth-century eclipse maps by Halley and Whiston

Earlier this month I published a post at the H Word on ‘Halley’s Eclipse’ of 1715. It has been associated with Edmond Halley because, using the best theory and data then available, he made impressively accurate predictions of its timing and path, publicised through a broadsheet map and the Royal Society. As I explain in the post, however, he was not the only one to do so: London was a competitive market for scientific publications and authority.

This post is an appendix, where I can show more of the eclipse maps published than I could on the Guardian’s website. I should add, too, that these were not the first predictions or maps of solar eclipses, and that there were earlier German, Dutch and French maps.

Here, however, is Halley’s first map, from Eclipse Maps, which was published in advance of the event, encouraging observation. It is titled “A Description of the Passage of the Shadow of the Moon over England, In the Total Eclipse of the Sun, on the 22d Day of April 1715 in the Morning”. I am not sure where the original is kept, but it may be the same as that reproduced in black and white in Jay Pasachoff’s article on Halley’s eclipse maps, which is from the Houghton Library. The full text, which is not high enough resolution to read here, has been transcribed by Pasachoff.

Halley's predictive map of the 1715 eclipse, from Eclipse-Maps.com.
Halley’s predictive map of the 1715 eclipse, from Eclipse-Maps.com.

Halley seems to have produced more than one edition of the map before 22 April 1715 (O.S. – the anniversary was celebrated on 3 May N.S.), and also one after the event, showing the path as corrected by observations. This copy of his “A Description of the Passage of the Shadow of the Moon over England as it was Observed in the late Total Eclipse of the Sun April 22d, 1715 Manè” is from the Institute of Astronomy, University of Cambridge, where you can see some superbly high-resolution images.

Halley's map of the 1715 eclipse, produced and corrected after the event. Institute of Astronomy, University of Cambridge
Halley’s map of the 1715 eclipse, produced and corrected after the event. Institute of Astronomy, University of Cambridge

Halley came back to his winning formula when another eclipse rolled along. His map, published in 1723 (annotated November 17123 here), showed both the recomputed path of the 1715 eclipse and the predicted path of 11 May 1724. This image is from the Houghton Library’s Tumblr, where it is available in higher resolution. The text declares that the first map “has had the desired effect” in encouraging observation and uses this one to demonstrate that his predictions had been pretty good in 1715 and were worth acting on again.

Halley's map showing the 1715 and 1724 solar eclipses. Houghton Library (EB7 H1552 715d2b).
Halley’s map showing the 1715 and 1724 solar eclipses. Houghton Library (EB7 H1552 715d2b).

However, as my post discussed, William Whiston was also in the business of predicting eclipses and selling scientific paraphernalia.  Like Halley, he was making predictions based on John Flamsteed’s observations at the Royal Observatory and corrected with Isaac Newton’s theory, and encouraging observations. Whiston made comparison of his observations with Halley’s and his  two eclipse-predicting broadsheets are again from the Cambridge Institute of Astronomy’s Library here and here.

The one I think is the earlier from Whiston was dated 2 April 1715 and titled “A Compleat Account of the great Eclipse of the Sun which will happen Apr. 22 in the Morning”. It is much more text-heavy and technical in content, and the map is a celestial one, showing the positions of the heavenly bodies rather than the path of the shadow on Earth.

Whiston's broadsheet predicting the timing and path of the 1715 comet. Institute of Astronomy, University of Cambridge (AMI/11/B).
Whiston’s broadsheet predicting the timing and path of the 1715 comet. Institute of Astronomy, University of Cambridge (AMI/11/B).

A second broadsheet by Whiston did show the Sun’s shadow on the Earth, but from a global point of view. The title too emphasised that this was not just an English matter: “A Calculation of the Great Eclipse of the Run, April 22d 1715 in ye Morning, from Mr Flamsteed’s Tables; as corrected according to Sr Isaac Newton’s Theory of ye Moon in ye Astronomical Lectures; with its Construction for London Rome and Stockholme”. It also advertised an instrument that could be bought from Whiston.

Whiston's second 1715 eclipse broadsheet. Institute of Astronomy, University of Cambridge (AMI/11/C).
Whiston’s second 1715 eclipse broadsheet. Institute of Astronomy, University of Cambridge (AMI/11/C).

John Westfall and William Sheehan’s new book on observing eclipses, transits and occultations, indicates the Whiston and Halley’s estimates varied by about 25 miles, which perhaps puts the more triumphant claims of accuracy in perspective. I think (correct me below if I am wrong) that Halley’s prediction was the more accurate, but there was an element of luck involved. Above all, his map, showing geographical detail of England beneath the path of totality, was much more persuasive and appealing – this is the main reason that the 1715 eclipse became ‘Halley’s’.

Whiston had learned the importance of the image by 1724. His “The Transit of the Total Shadow of the Moon” this time showed familiar coastal outlines, although again other parts of Europe were included: Paris would be a better observing site than London this time. This version is from the Science & Society Picture Library and belongs to the Royal Astronomical Society.

Whiston's map showing the predicted path of the 1724 eclipse. Science & Society Picture Library/Royal Astronomical Society.
Whiston’s map showing the predicted path of the 1724 eclipse. Science & Society Picture Library/Royal Astronomical Society.

And so the maps continued: there are many to explore in the wonderful albums at Eclipse Maps. It was a flourishing business come eclipses in the 1730s and beyond, especially that of 1764, as many publishers jumped on the opportunity that Halley and Whiston had spotted in 1715. So too, of course, had the person that links all the images shown here: the engraver and cartographer John Senex, who deserves a much fuller biography on Wikipedia than this!

 

Maskelyne: Astronomer Royal – book now available

Now available from the publisher, Robert Hale Books currently cheaper than AmazonMaskelyne: Astronomer Royal has been edited and partly written by me, with contributions from seven other curators and historians of science.

9780719809125

 

Stemming from a public symposium at the National Maritime Museum in 2011, marking the bicentenary of Maskelyne’s death, the book aims to be readable. It is also very well illustrated, particularly with photographs of objects, drawings and papers from the Museum’s Maskelyne collection. The full contents are as follows:

Introduction (Rebekah Higgitt)

Chapter 1: Revisiting and Revising Maskelyne’s Reputation (RH)

Case study A: The longitude problem (RH)

Chapter 2: ‘The Rev. Mr. Nevil Maskelyne, F.R.S. and Myself’: The Story of Robert Waddington (Jim Bennett)

Case study B: The projects of eighteenth-century astronomy (RH)

Chapter 3: Maskelyne the Manager (Nicky Reeves)

Case study C: The Astronomer Royal at Greenwich (RH)

Chapter 4: Nevil Maskelyne and his Human Computers (Mary Croarken)

Case study D: Maskelyne and the marine timekeeper (RH)

Chapter 5: Maskelyne’s Time (Rory McEvoy)

Case study E: Instruments of exploration (RH)

Chapter 6: ‘Humble servants’, ‘loving friends’, and Nevil Maskelyne’s Invention of the Board of Longitude (Alexi Baker)

Case study F: The Royal Society and Georgian science (RH)

Chapter 7: Friend and foe: The Tempestuous Relationship Between Nevil Maskelyne and Joseph Banks (Caitlin Homes)

Case study G: Visualizing and collecting the Maskelynes (RH) 

Chapter 8: The Maskelynes at Home (Amy Miller)

Coda: A life well lived (RH)

Cosmos and Giordano Bruno: the problem with scientific heroes

Cross-posted from The H Word blog.

 

Statue of Giordano Bruno, erected at Campo de' Fiori in Rome, 1889.
Statue of Giordano Bruno, erected at Campo de’ Fiori in Rome, 1889.

Although it’s not as big news in the UK as it has been in the US, readers of the Guardian science pages may have noticed that Carl Sagan’s classic series Cosmos: A Personal Voyage is being remade by Fox and presented by Neil deGrasse Tyson as Cosmos: A Spacetime Odyssey.

Broadcast in the US last Sunday, I saw a lot of love being expressed on my Twitter timeline. However, it has also prompted some interesting comments from historians of science. We in the UK can see it for ourselves this Sunday (if we have access to the right channels), but here are some articles and posts that give food for thought.

In The Atlantic, Audra Wolfe looked at the Cold War context in which the original Cosmos succeeded, or could, at least, be credited by many with having kicked off a decade-long “popular science boom”. What the Cosmos effect actually was does not seem to have been measured but, even if real, Wolfe points out that times have changed. She argues that Cosmos Can’t Save Public Support for Science today, particularly if it is “weigh[ed] down with Cold War-era fantasies that confuse the public understanding of science with its appreciation.”

Other historians have been prompted to comment on Cosmos because, as in the original, history of science is part of the package. Much has been said about the importance the remake, as a high-profile broadcast that can reflect the extent to which science has moved on since 1980. History of science has also moved on: is this reflected in the new series?

The answer, it seems, is yes (a bit) and (mostly) no. In the first episode, a rather hefty portion of airtime (11 out of 43 minutes) is devoted to an animation on the life of Giordano Bruno. Burnt at the stake by the Roman Inquisition in 1600, he was there to play the role of scientific hero and martyr. It is an ill-fitting part for this idiosyncratic Dominican monk.

Laudably avoiding any temptation to snark, Meg Rosenburg took the sudden interest in this reasonably obscure figure as an opportunity to help those who might Want to Know More About Giordano Bruno. While Bruno’s cosmological poetry and mystical thought included heliocentrism, he was not, of course, a scientist, nor was he sentenced to death for “scientific” ideas or anything like “the nice-mannered, doe-eyed dissenter” that appears on the screen.

In fact, Bruno is so obviously a problematic choice as a scientific martyr that several non-historians have also picked up on the issue. Corey S. Powell in Discover Magazine suggested that Cosmos picked the wrong hero, and that another – even more obscure but significantly more astronomical – early Copernican, Thomas Digges, might have been a better bet. Hank Campbell at The Federalist picked the Bruno problem as the most significant of Five Things that Cosmos Gets Wrong.

Becky Ferreira at Motherboard carefully explained What Cosmos Gets Wrong About Giordano Bruno, the Heretic Scientist, although, as she notes, it was not all bad as the account “did a pretty good job of covering its butt by shoehorning in some of Bruno’s contradictions, like the fact that he was a crappy scientist (and many historians argue he shouldn’t be considered one at all).”

Yet, nevertheless, the overriding message appears to have been about heroic passion for truth against dogma and science versus religion. And, despite the nod the nuance, this is a case of turning history into parable.

This is problematic for many reasons, one of which is that it doesn’t exactly sit well with claims to champion evidence-based knowledge. Another is that hiding parts of Bruno’s story that undermine the image of the scientific martyr plays into the hands of those who are only too pleased to highlight what might appear to be anti-religious propaganda coming from the scientific and media establishment (thanks to Rosenburg for tweeting that link).

Historical figures who lived in a very different world, very differently understood, cannot be turned into heroes who perfectly represent our values and concerns without doing serious damage to the evidence. It reminds me of one of the 19th-century men of science-cum-historians I researched, who learned this lesson the hard way.

In 1831 David Brewster published a short biography of Isaac Newton, portraying him as a hero that represented everything the author wanted to say about the moral status of science and its practitioners, and how they should be supported in late Georgian Britain. A couple of decades later he produced a much expanded biography, this time based in part on the unpublished archive. Lo and behold: Newton was a nasty piece of work, he was unorthodox in his Christian belief and he was a dedicated alchemist.

Poor Brewster! Although, as a reviewer said, he attempted to “do his best” by his hero, he was sufficiently dedicated to the evidence to “admit” the faults in public. It undermined his overriding narrative and seems to have caused him real personal anguish. Let this be a cautionary tale against those who invest too much in their heroes – and a call for some evidence-based history to help us better understand what science has been, is now and could be in the future.

 

Picturing science: inside a Georgian observatory

Cross-posted from The H Word blog.

Detail of Shirburn Castle Observatory

Detail of engraving of the observers at Shirburn Castle Observatory. Source: National Maritime Museum

*

I only recently, and by accident came across this rather delightful 1778 mezzotint by James Watson among the collections of the National Maritime Museum. It was a somewhat hidden gem, having not been fully catalogued, although there are copies to be found elsewhere.

I have now updated the description, having realised that the full imageshows two servants-cum astronomical assistants of George Parker, 2nd Earl of Macclesfield (c.1696-1764). They are depicted in his private and exemplary observatory at Shirburn Castle, erected in about 1739.

In the detail at the top of this post is Thomas Phelps, then aged 82, and with him (see below) is John Bartlett, then aged 54. Most of what we know about them is what appears in the text given within this engraving. It is a tale of common men made good, thanks to natural ability, hard work, access to books and recognition by their superiors.

Detail of Shirburn Castle Observatory

Phelps, “who from being a stable-boy in the year 1718, to the then Lord Chief Justice Parker, afterwards Earl of Macclesfield, rose by his merit to the upper employments in that family, and at last, for his uncommon genius, was promoted to be observer, in their Observatory”. John Bartlett was “originally a shepherd, in which station he by books and observation acquired such a knowledge in computation, and of the heavenly bodies, as induced the late George, Earl of Macclesfield, to appoint him assistant observer in his Observatory”.

Phelps and Bartlett are shown in the observatory’s transit room, with Phelps at the eye-piece of the 5-foot transit telescope, made byJonathan Sisson. This instrument is fixed to supporting pillars and aligned to the meridian in order ensure the accuracy of repeated positional measurements of the heavenly bodies.

Behind Bartlett is an astronomical regulator, an accurate observatory clock, by George Graham. To the left is an equatorially-mounted telescope, probably by John Dollond, These were tip-top London instrument makers. Macclesfield spared no expense to create an observatory that, with a salaried observer and assistant, rivalled or, indeed, trumped the establishment at the Royal Observatory in Greenwich.

Macclesfield was a remarkable individual. He was instructed in mathematics by Abraham De Moivre and William Jones, and the sciences became his passion. Under Jones’s influence he formed an exceptionallyimportant collection of 17th-century mathematical manuscripts andbooks. He erected his observatory with the assistance of James Bradley, then Savilian Professor of astronomy at Oxford and later Astronomer Royal. He also built a chemical laboratory, in which his observer, Thomas Phelps also assisted.

Macclesfield was, as well as being an MP, President of the Royal Society for 12 years, from 1752 until his death. From both positions he was a principal proponent of the adoption of the Gregorian calendar. His son, Thomas Parker, 3rd Earl of Macclesfield, was also elected FRS, and evidently kept the observatory going, under Phelps and Bartlett, joined in about 1776 by someone called Redding. Regular observations seem to have ceased in the 1790s.

This engraving is a remarkable celebration of two relatively unknown individuals who, otherwise, survive only in the manuscript observations. It is relatively rare, before the advent of photography, that we see images of people engaged in the activity of astronomical observation. It is also rare to see the assistants, rather than the owner of such fine instruments.

The engraving is, of course, also a celebration of those instruments, which were still impressive in the 1770s. In addition to the telescopes and clock, core tools of the well-quipped working observatory, is a celestial globe. This plays a iconographic rather than a practical function, and is unlikely to have been placed in the observatory itself.

Detail of Shirburn Castle Observatory

However, perhaps my favourite part of the image depicts some rather more humble, but no less essential, aspects of observatory equipment. They are a ratcheted, adjustable observing chair, against which Phelps leans, and the pen and paper with which Bartlett notes the time on the clock at the moment that Phelps calls a star as crossing the meridian of the telescope.

Detail of observing chair in Shirburn Castle observatory

These ordinary things – a chair and writing materials – remind us that the work of these observers was not simple star-gazing but, even in this private observatory, something precise, regular, regulated and tiring. It was the hard work of making and recording observations with an eye to posterity.

Picturing science: sharing knowledge, selling ideas

William Huggins' depiction of the solar surface. Source: National Maritime Museum
William Huggins’ depiction of the solar surface (National Maritime Museum)

This image looks like a curving, curling, abstract mosaic. It is, in fact, an attempt to capture what one observer saw when he looked through a filtered telescope lens at the Sun’s surface. Before photography developed, if astronomers wanted to share their visual experience they could only do it by drawing, adding an ability with pencil to the many necessary accomplishments of the observer. Photographing detail on the bright Sun was to prove a particular challenge.

When you know what it is you should be looking for, it is much easier to see. Familiar as we are today with spectacular images of the Sun in all kinds of different wavelengths, we have come to expect pattern, difference, structure, feathery and filament-like shapes and vast bursts of gases. This was unknown before telescopes could supply sufficient magnification and resolution.

Careful drawings were backed by verbal descriptions, but it was only by looking for themselves that other astronomers might come to accept your interpretation. Was the surface pattern “feathered”, “granulated”, “rice-grain”, “slashed straws” or “willow-leaf”? These were all terms used by observers like William HugginsSamuel Pierpont Langley and James Nasmyth, who revealed that the Sun was not the anticipated smooth, bright disc, punctured only by a few sunspots.

These images tell two stories. One is about the astronomers who looked at, tried to capture and explain the nature of the solar surface. The other is about sharing those images, knowledge and possible explanations with a wider public. These solar close-ups were published in scientific papers, but I have taken them from a set of 38 lantern slides, produced toillustrate lectures on the Sun by a company called York & Son in around 1880.

Drawing of sunspots by James Nasmyth (National Maritime Museum)
Drawing of sunspots by James Nasmyth (National Maritime Museum)

The set includes images that show observational instruments, experimental or demonstration equipment and diagrams to explain possible theories of solar activity. The slides allowed the lecturer to, for example, introduce the audience to competing explanations of the appearance of sunspots. William Herschel had suggested that they were openings in the Sun’s luminous atmosphere, revealing a cooler surface beneath; Alexander Wilson considered them depressions in the solar surface.

Experiment for using a prism to split sunlight (National Maritime Museum)
Experiment using a prism to split sunlight (National Maritime Museum)

I don’t know how many of this set of slides were produced, nor whether any of them were used to enliven one or more actual lectures on the Sun (apart from my own). If they did, the part on sunspots and the solar surface might have run similarly to this 1872 article in the Popular Science Monthly, by the editor Edward Livingston Youmans. While sunspots had, of course, been long known, their complex structure was newly revealed:

But, when a telescope of high magnifying power is directed to the sun, its aspect is greatly changed: the spots lose their simplicity, and the photosphere its uniformity, and in both there are a revelation of structure, a diversity of parts, and a variety of changes, which at once provoke questions in the mind of the observer, as to the causes of this diversified appearance, and the constitution of the body which presents them. The hypotheses put forth are ingenious; but, while the facts of observation are rapidly increasing, and there is a growing agreement on many points, there is still profound uncertainty as to the interpretation to be given to the leading phenomena.

An article or a lecture on the Sun, presented in the last quarter of the 19th century would have introduced its audience to a whole new vocabulary of penumbra, faculae and photosphere. It would also have focused on the use of novel techniques in astronomy, above all the photography and spectroscopy that opened the way to a whole new branch of science. It also introduced the idea that surface irregularities on the Sun might be linked to magnetic activity and terrestrial climate.

It was an exciting topic for a lecture around 1880 – something that a commercial producer of visual aids probably rightly took up as an opportunity.

Messing with time

Cross-posted from The H Word blog, first posted on 31 March 2013, the first day of British Summer Time.

Analogue clock

It’s hardly surprising that I’ve become very aware of time and how we measure it since beginning work at the Royal Observatory Greenwich. What has really struck me is how much we, on the one hand, are resentful at any suggestion that we alter the way we measure time and, on the other, have done just that many times over the course of history.

Although it’s useful publicity for the Observatory, I never cease to be amazed that the change of the clocks, which happens twice a year ever year like … err… clockwork, is always a news story. Suggestions that we might do away with British Summer Time, or shift to what is euphemistically called Double Summer Time (aka Central European Time) are huge debating points. The fact that we do, or the fact that we might cease to, add leap seconds are stories that both receive many column inches.

Although the introduction of BST was a very 1900s notion of making better – that is, more healthful and productive – use of our long summer days*, history suggests that it takes something like a world war to implement such seemingly radical changes. There is often a sense that diverting from whatever it is we are used to is, somehow, unnatural. It certainly seems unnatural when we are ripped untimely from our beds but, even before the arrival of this annual ritual, there was nothing natural about the way we measured time.

Take GMT, which traditionalists are keen to defend by rejecting summer time and by adding leap seconds to ensure that we do not drift too far from having the midday sun above the meridian at Greenwich at noon. In the scheme of things, it is almost as much of a novelty as BST. It only became official standard time in Britain in 1880, even if it had been used in specific contexts, like railway timetables or in navigation, some time before. Its use as a standard to which international time zones are aligned was a matter of slow adoption from the late 19th century onward.

The implementation of a national standard time, which might be some 20 minutes different from your local time, should you live in the west of the country, was seen by some as an unnecessary novelty. There were those who made a stand, and even today the chimes at Christ Church in Oxford still stick to local time. As can be imagined, the idea being floated at the end of the 19th century that there might be a universally-adopted International Time was much mocked, resented or worried about.

But the national or local times that seemed more meaningful to people are, of course, also artificial products. They are expressed as mean time, which is an averaging out of Sun’s the apparent motion that was adopted in deference to the introduction of a new technology – the clock. Clock time is produced by an artificial system that imperfectly mimics “real” time, which is a product of the Earth’s daily rotation and annual orbit.

The difference between mean time and “real” or apparent time is expressed by what’s called the Equation of Time. This was first calculated in the second half of the 17th century, when the introduction of pendulum clocks made the business of artificial timekeeping sufficiently precise. The fact is, the Sun is rarely at its highest point over the Greenwich meridian at the moment our watches show noon.

Things get even more complex when we start looking into how calendars have been calculated and established. These are fascinating histories that are intertwined with everything from the story of astronomy to how we live and order our lives. Our time has been messed with for centuries and it is not, forgive the pun, a clock that can be turned back.

* Personal gripe: many people seem to think that putting the clocks back in Winter is “daylight saving” and is designed, somehow, to give us more daylight. Guys: “daylight saving” is used in Summer and nothing, but nothing, will create more daylight in Winter.

Book review: Venus Seen on the Sun

This review was first published in the British Journal for the History of Science 46 (March 2013)

Jeremiah Horrocks and Wilbur Applebaum (trans.), Venus Seen on the Sun: The First Observation of a Transit of Venus by Jeremiah Horrocks. Leiden: Brill, 2012. Pp. xxiv +82. ISBN 978­90­04­22193­2. €99.00 (hardback). 

Jeremiah Horrocks' observation of the 1639 transit of Venus, as published by Johannes Hevelius with Horrocks' Venus in sole visa in 1662.
Jeremiah Horrocks’ observation of the 1639 transit of Venus, from Johannes Hevelius’ version of Venus in sole visa (1662).

The June 2012 transit of Venus was the occasion to turn our attention once again to the observers of the previous transits, in 1639, 1761, 1769, 1874 and 1882. Thus it is that we have the first English translation since the nineteenth century of Jeremiah Horrocks’s account of his 1639 observation. This seems long overdue, especially given the fact that the only other available translation, which is ‘more free in style than necessary’ (p. xxii), was produced by someone who lacked familiarity with the history of astronomy and introduced a number of errors.

The text of Venus in Sole visa, first published by Johannes Hevelius in 1662, is not only an account of the first observation of this rare event but also a fascinating commentary on astronomy at a period of significant change. The transit gave Horrocks the opportunity to judge and correct the work of Copernicus, Lansberge, Longomontanus and Kepler, with the Rudolphine Tables of the last being proved much the superior. It was this, rather than the observation itself, or even its indication of the planets’ great distance and lack of luminosity, that marked the significance of the work. In addition, the text is remarkably readable: as Applebaum writes in the brief introduction, ‘It is filled with an unrestrained enthusiasm and intensity of commitment from which a youthful and refreshing naiveté is never wholly lacking’ (p. xxiii).

Short though the introduction is, it helpfully outlines Horrocks’s life, the history of the four draft manuscripts of the treatise, and the astronomical context in which it was produced and read. Applebaum’s notes in the main text are full and extremely helpful, in technical matters and in relation to the books and manuscripts that Horrocks was referring to, both scientific and literary. I cannot comment on the faithfulness of the translation but it reads well, with the exception, perhaps, of Horrocks’s poetry, which has been translated for meaning rather than scansion.

A sense of Horrocks’s personality arises from the text, in part due to his adhering to ‘a style now completely gone from scientific literature’ (p. xxiv). There is infectious zeal, leading to amusingly damning judgements, as well as the poetry, digressions and classical allusions. (The transit of Venus is a subject for which coy personifications and metaphors of seduction seem not yet to have gone out of style.) It is not hard to see why successive readers of Horrocks have taken him to their hearts. The Victorians, with Arundell B. Whatton’s 1859 Memoir and a series of essentially fictional memorials and portraits, naturally led the way, bequeathing their vision of a pious and persevering young cleric, fighting ill health to perform first his Christian and then his scientific duty.

Jeremiah Horrocks' observation of the transit of Venus, as imagined in 1891 by Eyre Crowe
Jeremiah Horrocks’ observation of the transit of Venus, as imagined in 1891 by Eyre Crowe

We, no less enthused by a local hero with his finger on the pulse of Continental astronomy, will still rejoice in the account of a young astronomer’s greatest moment. Although touched by the thought of his work being cut short by tragically early death, Horrocks nevertheless comes across as wonderfully vital. The modern, positively reclaimed term ‘geek’ comes to mind in reading Horrocks’s description of astronomers who ‘immoderately delight in trifling things, which do not move others in the least’ (p. 16). Something similar arises from his lauding of Kepler, ‘the unparalleled prince of true astronomy’ (p. 51), and his dismissal of the ‘boasts’ and ‘impotent clamour’ (p. 72) of Philippe van Lansberge and those who relied on his tables.

Apart from Kepler, Horrocks’s greatest praise is for ‘the recent and wonderful invention of the telescope’ (p. 8). Despite writing three decades after the instrument was patented, Horrocks clearly felt that ‘the Belgian telescope’ still required a better reputation, and thus he affirmed the increased accuracy it allowed and defended it against those who suggested it could create illusions. It is eulogized in verse, as readers are urged to ‘learn the wonders of such a great tube’ (p. 11) and join him, lying in wait to spy Venus.

Being a review of a book published by Brill, this must end with the inevitable comment about cost. Ninety-nine euros for just over a hundred pages is steep by any measure. Given the accessible style of Horrocks’s writing and Applebaum’s translation, it is a shame that this should simply be a library-based reference work. The author’s preface promises a full-length biography of Horrocks in the near future. It is much to be hoped that this does indeed appear, and that it is available at a price that places it within reach of significantly more pockets.

Picturing science: comet watching

Cross-posted from The H Word blog.

Detail of a caricature showing a man watching a comet
‘Looking at the comet till you get a criek in the neck’. Detail of a caricature by
Thomas Rowlandson, 1811. Source: National Maritime Museum
Having begun my series called Picturing Science, I realised that I have stolen the title of another website, which does at least give me an excuse to point those interested in imagery in the history of science to the Origins of Science as a Visual Pursuit project. This fascinating academic project is looking in detail at images as an integral part of doing science, while my series is – for now at least – more focused on science in the public sphere.

Thus, while last week’s fanciful image was produced in the sober, educational context of an encyclopedia, this week’s takes us from the heavens right down to earth. It is a caricature by Thomas Rowlandson, published by Thomas Tegg in 1811, and can be viewed in full here.

On one level the print satirises the increasing popular interest in astronomy in the first half of the 19th century. With telescopes increasingly affordable, and comets in the news, there were undoubtedly more individuals than ever who, like this man in his nightcap and nightgown, were straining to view the heavens until they “get a criek [sic] in the neck”.

1805 had seen what is now known as Encke’s comet and Biela’s comet, two years later there was the much more spectacular Great Comet of 1807. In the year that this print was published, another bright comet, with a remarkable reddish colour and broad tail, was visible to the naked eye for around 260 days. This was the Great Comet of 1811.

As so often, in history and even today, the appearance of a bright comet was connected to particular events on earth. 1811, for example, saw a particularly good wine vintage, and so Comet Wine was marketed. However, it was also interpreted as having portended Napoleon’s invasion of Russia the following year – not least by Napoleon himself – and became known as Napoleon’s Comet. However, something else of earthly – or, perhaps, earthy – concern is happening in this caricature.

Detail from a caricature showing a man watching a comet while his wife enjoys the attentions of another manWhile the old man’s eye is glued to his telescope, and his mind contemplating the heavens, another man takes advantage of the situation, paying lascivious attention to the astronomer’s young and attractive wife. Just to make the relationship clear, her fur stole appears to add a tail to the older man – a symbol, like horns, of the cuckold.

This joke, about astronomers and enthusiasts being so wrapped up in their ideas, views of nature and gadgets that they fail to see what is going on under their noses, is an old one. It appears in Gulliver’s Travels among the inhabitants of the floating island Laputa, who I mentioned inmy post on Swift and satire. It is, unsurprisingly, a common trope of caricature, something I discussed with some other examples in an old post on caricaturing astronomers.

You can see some other distracted astronomers and some 19th-century comet imagery from the National Maritime Museum’s collections and elsewhere on my Pinterest boards. Also on Pinterest are some morePutti of Science, collected by Danny Birchall after last week’s optical putti.

Drawing Mars in Greenwich: recreating an experiment for Stargazing Live

Cross-posted from The H Word blog.

Recreating Mars drawing experiment in Greenwich
Filming for Stargazing Live at Queen’s House in Greenwich. Photograph: Marek Kukula

This week [NB This post was first published on 7 January 2013] sees the return of the BBC’s highly successful Stargazing Live. It starts on Tuesday, in an episode that follows last year’s biggest astronomy story by focusing on Mars.

In thinking about the search for possible life on Mars, the programme will include some of the historical observations and debates that I discussed in a previous post. I’m delighted that the programme gave us at theRoyal Observatory a chance to recreate a key Greenwich contribution to the story.

This was the 1903 experiment carried out by E. Walter Maunder, an assistant at the Observatory, exploring perception at the limits of vision. It was one element in his campaign against the then-dominant view that the Martian surface was covered with immensely long, wide and straight “canals”, thought by many to the work of an advanced civilisation.

Maunder was not alone, being joined by Eugène Michel Antoniadi andWilliam Campbell, together described in Michael J. Crowe’s The Extraterrestrial Life Debate as “the leaders of a wrecking crew” that demolished the Martian canals.

Maunder, with the assistance of the headmaster of the Royal Hospital School in Greenwich, asked a number of the school’s pupils to draw from different depictions of Mars, placed on a board at the front of the room.His results suggested that, particularly at certain distances, the eye tended to resolve indistinct waves and dots into straight lines, suggesting that the “canals” were an optical illusion rather than real surface features.

Ever since I heard about this experiment, I have wanted to recreate it. Asking people to undertake an exercise like this is a wonderful way to understand the problems and contingencies surrounding astronomical observation and recording (imagine not only peering at this small image, but it flickering in an unsteady atmosphere, and having to keep taking your eyes away in order to represent it on paper). I also wondered if it really worked as Maunder described.

Maunder claimed in his paper that the boys, aged around 12 to 14, were all “wholly and entirely ignorant of the appearance of Mars in the telescope, and of the discussions which have taken place as to the markings on his surface.” I have always wondered if this was true, given the widespread popularity of the Martian canal idea at this period.

Our guinea pigs were probably familiar with what Mars looks like when photographed today, but less likely than the 1903 schoolboys to think of drawings or canals. An interesting difference was their age and the fact that most of them were art students. This probably produced different results than had we picked people off the street but might compare interestingly with the naval cadets. The latter were encouraged by Maunder, and probably by their education, simply to draw what they could see. Our art students may have been more likely, despite my instructions, to attempt to interpret the image and to consider different graphic approaches to its re-depiction.

It is likely that the experiment took place in the school’s old gymnasium. This no longer exists, so the BBC team opted for another of the school’s former buildings – the beautiful Queen’s House. They set up the experiment pretty faithfully, with distances and scales as specified in Maunder’s paper. Told to draw, our students obliged, and demonstrated that their eyesight and drawing ability was a good deal keener than mine.

Did our results back Maunder’s? Sort of. I didn’t see the generation of any “canals” where little or nothing appeared on the original image, but there were certainly more straight lines. In our small sample, it also appeared that the middle rows were more likely to see these lines than those nearest (who saw more detail) or those furthest away (who saw little distinctly). It could be argued that these distances mimicked the experience of observing with particular-sized telescopes, creating the conditions where the eye tends to resolve indistinct detail into non-existent straight lines.

Maunder’s report of this experiment apparently brought a key ally to the campaign against Martian canals – the veteran Canadian-American astronomer Simon Newcomb. It was, however, just one of the arguments brought – one of the simplest being the point that if straight canals like those reported by Percival Lowell did exist on the curved surface of Mars, they ought to appear curved to the observer on Earth.

In his writings, Maunder focused on scientific evidence and his own experiences as an astronomical observer. He chose to stay clear of the philosophical and religious dimension of the debate, despite the fact that his popular writings in astronomy were usually framed with natural theology and Biblical references.

Religious beliefs could support either position in the debate about the existence of life on other planets. However, it was clear that Maunder, an active member of a small pentecostal, adventist sect, believed man’s relationship with God and place in the universe were unique. He could not countenance intelligent, canal-building Martians – and thus his scientific arguments were motivated by religious belief.

Watch on Tuesday to see how the experiment went and how it fits into the long history of observing Mars and the search for extra-terrestrial life. Also visit Alien Revolution a small, free exhibition at the Royal Observatory, opening in March.

In the end the section of the film that included the experiment wasn’t run live on Stargazing, due to lack of time. Happily, the whole thing was made available online and you can see it here.

First catch your spider: astronomical arachnids

Cross-posted from The H Word.

Garden spider in web.

Spiders have played a key role in the history of astronomy. This is not simply in being creatures that have kept vigil with the nocturnal astronomer, who is inspired, Robert-the-Bruce-like, by their skill and tenacity, but something far more fundamental.

Spider silk was sufficiently fine, sufficiently uniform and sufficiently strong to be used in the focus of a telescope’s eyepiece for precise measurement. Rather than cross-hairs, astronomers spoke of “wires”, against which the position of a star might be read. Several such spider-silk “wires” or “threads” might help time the transit of a star across the local meridian or, moveable, help measure the distance between binary stars.

Looking the other day for something else, I was pleased to come acrossan 1894 article in the journal of the British Astronomical Association by one of the Royal Observatory’s assistants, E Walter Maunder, that was a how-to guide to “Making a Spider Line Reticule”.

My headline is taken from Maunder, who refers to “Mrs Glasse“, whoseThe Art of Cookery was famously supposed to have instructed readers to “First catch your hare”. In the spirit of the best how-to and make-and-mend housewife, Maunder was sharing his knowledge as money-saving advice for those who could not afford a professionally made filar micrometer. That said, spiders were being caught and used by astronomers at Greenwich for years, and were to be until at least the 1950s.

Unlike Mrs Glasse, Maunder had some hints on animal capture. The spider required was Epeira diadema, “the handsome coronetted spider of our gardens”, although “she has no astronomical monopoly” and an ordinary house spider might do. As he says, “The best time for a raid is the month of October” – until it recently turned cold I spotted many beautiful garden spiders with magnificent webs even in uninspiring urban front gardens.

To catch and keep your spider, she should be “lifted out of her web and placed in a small paper bag, the bag being closed by gently twisting up its mouth. Any number of spiders may be secured and kept ready for use when required if each one is imprisoned in a separate bag.”

Next comes the crucial step, with the acquisition of a “fork”, aka “a piece of wire bent into the shape of a U”, about 12-15 inches long, with the two points about 3 inches apart; “of sufficient width, that is, to well overlap the frame to be webbed, so as to give enough tension to the webs to keep them straight”.

Just previous to winding, the fork should be coated with the usual commercial “brown hard varnish.” The operator then mounts on a stool, so as to give his spider a further drop, places his fork ready to his hand, and taking the paper bag in his left hand, and a small straight piece of wood, gently lifts out the spider. The operator then takes the fork, and when the spider has dropped two or three feet, puts in his fork, and gently winds up, pushing forward the fork as it is rotated, so that the thread lies on it in a zig-zag manner. Other forks may be filled if the spider is in the humour for spinning. If Arachne is inclined, however, to be obstinate, gently blow on her with a full steady breath…

The filled forks were to be placed vertically for about an hour, after which time it was possible to pack them away in boxes until required.

Maunder’s article then carefully describes the process of fitting the threads to a frame, and fixing them at a proper tension with some more varnish – applied, he suggests, with another unlikely astronomical instrument: a knitting needle.

Of such things – and sealing wax and string – are the most distinguished careers made.