Tag: history of science

Aug 26 2015

Book Review: Stargazers–Copernicus, Galileo, the Telescope and the Church by Allan Chapman

stargazersIt’s been a while since my last book review here but I’ve just finished reading Stargazers: Copernicus, Galileo, the Telescope and the Church by Allan Chapman.

The book covers the period from the end of the 16th century, the time of Copernicus and Tycho Brahe, to the early 18th century and Bradley’s measurement of stellar aberration passing Galileo, Newton and others on the way. Conceptually this spans the full transition from a time when people believed in a Classical universe with earth at its centre, and stars and planets plastered onto crystal spheres, to the modern view of the solar system with the earth and other planets orbiting the sun.

This development parallels that in Arthur Koestler’s classic book "The Sleepwalkers”, however Chapman’s style is much more readable, his coverage is broader but not so deep. Chapman introduces a wealth of little personal anecdotes and experiments. For instance on visiting Tycho Brahe’s island observatory he recounts a meeting with a local farmer who had in his living room a marked stone from the Brahe’s observatory (which had been dismantled by the locals on Brahe’s death). Brahe was hated by his tenants for his treatment of them, a hate that was handed down through the generations. Illustrations are provided in the author’s own hand, which is surprisingly effective. He discusses his own work in reconstructing historical apparatus and observations.

Astronomy was an active field from well before the start of this period for a couple of reasons: firstly, astrology had been handed down from Classical times as a way of divining the future. To was believed that to improve the accuracy of astrological predictions better data on the locations of heavenly bodies over time was required. Similarly, the Christian Church required accurate astronomical measurement to determine when Easter fell, across increasingly large spans of the Earth.

The period covered by the book marks a time when new technology made increasingly accurate measurements of the heavens possible, and the telescope revealed features such as mountains on the moon, sunspots and the moons of Jupiter visible for the first time. Galileo was a principle protagonist in this revolution.

Amongst scientists there is something of the view that the Catholic Church suppressed scientific progress with Galileo the poster boy for the scientist’s case. Historians of science don’t share this view, and haven’t for quite some time. Looking back on Sleepwalkers, written in 1959 I noted the same thing – the historians view is generally that Galileo brought it on himself in the way he dismissed those that did not share his views in rather offensive terms. Galileo lived in a time when the well-entrenched Classical view of the universe was coming under increased pressure from new observations using new instruments. In some senses it was the collision with the long-held Classical view of the universe which led to his problems, the Church being more committed to this Classical view of the physical universe rather than to anything proposed in Scripture.

The role of the Church in promoting, and fostering science, is something Chapman returns to frequently – emphasising the scientific work that members of the Church did, and also the often good relationships that lay “scientists” of different faiths had with Church authorities.

Chapman introduces some of the lesser known English (and Welsh) contributors to the story. Harriet who made the earliest known sketches of the moon. The Lancashire astronomers, who made the first observations of the transit of Venus. John Wilkins whose meetings were to lead to the foundation of the Royal Society. He also notes the precedent of the Royal College of Physicians, formed in 1518. The novelty of the Royal Society when compared with earlier organisations of similar character was that the Fellows were responsible for new appointments, rather than them being imposed by a patron. This seems to have been an English innovation, repeated in the Oxbridge colleges, and Guilds.

Relating to these English astronomers was the development of precision instruments in England. This seems to have been spurred by the Dissolution of the monasteries. The glut of land, seized by Henry VIII, became available to purchase. The purchase of land meant a requirement for accurate surveying, and legal documents. Hence an industry was born of skilled men wielding high technology to produce maps.

I was distracted by the presence of Martin Durkin in the acknowledgements to this book, he was the architect of “polemical” Channel 4 documentary “The Great Global Warming Swindle”, so it cast doubt in my mind as to whether I should take this book seriously. On reflection Chapman’s position as presented in this book seems respectable, but it is interesting how a short statement in the acknowledgements made me consider this more deeply.

Overall, Stargazers is rather more readable than Sleepwalkers, not quite so single-tracked in it’s defence of the Catholic Church as God’s Philosophers and a different proposition to Fred Watson’s book of the same name, which is all about telescopes.

Jan 20 2015

Book review: Sextant by David Barrie

sextantThe longitude and navigation at sea has been a recurring theme over the last year of my reading. Sextant by David Barrie may be the last in the series. It is subtitled “A Voyage Guided by the Stars and the Men Who Mapped the World’s Oceans”.

Barrie’s book is something of a travelogue, each chapter starts with an extract from his diary on crossing the Atlantic in a small yacht as a (late) teenager in the early seventies. Here he learnt something of celestial navigation. The chapters themselves are a mixture of those on navigational techniques and those on significant voyages. Included in the latter are voyages such of those of Cook and Flinders, Bligh, various French explorers including Bougainville and La Pérouse, Fitzroy’s expeditions in the Beagle and Shackleton’s expedition to the Antarctic. These are primarily voyages from the second half of the 18th century exploring the Pacific coasts.

Celestial navigation relies on being able to measure the location of various bodies such as the sun, moon, Pole star and other stars. Here “location” means the angle between the body and some other point such as the horizon. Such measurements can be used to determine latitude, and in rather more complex manner, longitude. Devices such as the back-staff and cross-staff were in use during the 16th century. During the latter half of the 17th century it became obvious that one method to determine the longitude would be to measure the location of the moon relative to the immobile background of stars, the so-called lunar distance method. To determine the longitude to the precision required by the Longitude Act of 1714 would require those measurements to be made to a high degree of accuracy.

Newton invented a quadrant device somewhat similar to the sextant in the late 17th century but the design was not published until his death in 1742, in the meantime Hadley and Thomas Godfrey made independent inventions. A quadrant is an eighth of a circle segment which allows measurements up to 90 degrees. A sextant subtends a sixth of a circle and allows measurements up to 120 degrees.

The sextant of the title was first made by John Bird in 1757, commissioned by a naval officer who had made the first tests on the lunar distance method for determining the longitude at sea using Tobias Meyer’s lunar distance tables.

Both quadrant and sextant are more sophisticated devices than their cross- and back-staff precursors. They comprise a graduated angular scale and optics to bring the target object and reference object together, and to prevent the user gazing at the sun with an unprotected eye. The design of the sextant changed little since its invention. As a scientist who has worked with optics they look like pieces of modern optical equipment in terms of their materials, finish and mechanisms.

Alongside the sextant the chronometer was the second essential piece of navigational equipment, used to provide the time at a reference location (such as Greenwich) to compare to local time to get the longitude. Chronometers took a while to become a reliable piece of equipment, at the end of Beagles 4 year voyage in 1830 only half of the 22 chronometers were still running well. Shackleton’s mission in 1914 suffered even more, with the final stretch of their voyage to South Georgia using the last working of 24 chronometers. Granted his ship, the Endeavour had been broken up by ice and they had escaped to Elephant Island in a small, open boat! Note the large numbers of chronometers taken on these voyages of exploration.

Barrie is of the more subtle persuasion in the interpretation of the history of the chronometer. John Harrison certainly played a huge part in this story but his chronometers were exquisite, expensive, unique devices*. Larcum Kendall’s K1 chronometer was taken by Cook on his 1769 voyage. Kendall was paid a total of £500 for this chronometer, made as a demonstration that Harrison’s work could be repeated. This cost should be compared to a sum of £2800 which the navy paid for the HMS Endeavour in which the voyage was made!

An amusing aside, when the Ordnance Survey located the Scilly Isles by triangulation in 1797 they discovered its location was 20 miles from that which had previously been assumed. Meaning that prior to their measurement the location of Tahiti was better known through the astronomical observations made by Cook’s mission.

The risks the 18th century explorers ran are pretty mind-boggling. Even if the expedition was not lost – such as that of La Pérouse – losing 25% of the crew was not exceptional. Its reminiscent of the Apollo moon missions, thankfully casualties were remarkably low, but the crews of the earlier missions had a pretty pragmatic view of the serious risks they were running.

This book is different from the others I have read on marine navigation, more relaxed and conversational but with more detail on the nitty-gritty of the process of marine navigation. Perhaps my next reading in this area will be the accounts of some of the French explorers of the late 18th century.

*In the parlance of modern server management Harrison’s chronometers were pets not cattle!

Dec 28 2014

Book review: Maskelyne – Astronomer Royal edited by Rebekah Higgitt

MaskelyneOver the years I’ve read a number of books around the Royal Observatory at Greenwich: books about finding the longitude or about people.

Maskelyne – Astronomer Royal edited by Rebekah Higgitt is unusual for me – it’s an edited volume of articles relating to Nevil Maskelyne by a range of authors rather than a single author work. Linking these articles are “Case Studies” written by Higgitt which provide background and coherence.

The collection includes articles on the evolution of Maskelyne’s reputation, Robert Waddington – who travelled with him on his St Helena trip, his role as a manager, the human computers used to calculate the tables in the Nautical Almanac, his interactions with clockmakers, his relationships with savants across Europe, his relationship with Joseph Banks, and his family life.

The Royal Observatory with its Astronomer Royal was founded by Charles II in 1675 with the goal of making astronomical observations to help with maritime navigation. The role gained importance in 1714 with the passing of the Longitude Act, which offered a prize to anyone who could present a practical method of finding the longitude at sea. The Astronomer Royal was one of the appointees to the Board of Longitude who judged applications. The observations and calculations done, and directed, from the Observatory were to form an important part of successful navigation at sea.

The post of Astronomy Royal was first held by John Flamsteed and then Edmund Halley. A persistent problem to the time of Maskelyne was the publication of the observations of the Astronomers Royal. Flamsteed and Newton notoriously fell out over such measurements. It seems very odd to modern eyes, but the observations the early Astronomers Royal made they essentially saw as their personal property, removed by executors on their death and thus lost to the nation. Furthermore, in the time of Maskelyne the Royal Observatory was not considered the pre-eminent observatory in Britain in terms of the quality of its instruments or observations.

Maskelyne’s appointment was to address these problems. He made the observations of the Observatory available to the Royal Society (the Visitors of the Observatory) on an annual basis and pushed for the publication of earlier observations. He made the making of observations a much more systematic affair, and he had a keen interest in the quality of the instruments used. Furthermore, he started the publication of the Nautical Almanac which provided sailors with a relatively quick method for calculating their longitude using the lunar distance method. He was keenly aware of the importance of providing accurate, reliable observational and calculated results.

He was appointed Astronomer Royal in 1765 not long after a trip to St Helena to make measurements of the first of a pair of Venus transits in 1761, to this he added a range of other activities which including testing the lunar distance method for finding longitude, the the “going” of precision clocks over an extended period and Harrison’s H4 chronometer. In later years he was instrumental in coordinating a number of further scientific expeditions doing things such as ensuring uniform instrumentation, providing detailed instructions for observers and giving voyages multiple scientific targets.

H4 is a primary reason for Maskelyne’s “notoriety”, in large part because of Dava Sobel’s book on finding the longitude where he is portrayed as the villain against the heroic clockmaker, John Harrison. By 1761 John Harrison had been working on the longitude problem by means of clocks for many years. Sobel’s presentation sees Maskelyne as a biased judge, favouring the Lunar distance method for determining longitude acting in his own interests against Harrison.

Professional historians of science have long felt that Maskelyne was hard done by Sobel’s biography. This book is not a rebuttal of Sobel’s but is written with the intention of bringing more information regarding Maskelyne to a general readership. It’s also stimulated by the availability of new material regarding Maskelyne.

Much of the book covers Maskelyne’s personal interactions with a range of people and groups. It details his exchanges with the “computers” who did the lengthy calculations which went into the Nautical Almanac; his interactions with a whole range of clockmakers for whom he often recommended to others looking for precision timepieces for astronomical purposes. It also discusses his relationships with other savants across Europe and the Royal Society. His relationship with Joseph Banks garners a whole chapter. A proposition in one chapter is that such personal, rather than institutional, relationships were key to 18th century science, I can’t help feeling this is still the case.

The theme of these articles is that Maskelyne was a considerate and competent man, going out of his way to help and support those he worked with. To my mind his hallmark is bringing professionalism to the business of astronomy.

In common with Finding Longitude this book is beautifully produced, and despite the multitude of authors it hangs together nicely. It’s not really a biography of Maskelyne but perhaps better for that.

Sep 21 2014

Book review: Falling Upwards by Richard Holmes

fallingupwardsI read Richard Holmes book The Age of Wonder some time ago, in it he made a brief mention of balloons in the 18th century. It pricked my curiosity, so when I saw his book Falling Upwards, all about balloons, I picked it up.

The chapters of Falling Upwards cover a series of key points in the development of ballooning, typically hydrogen balloons from the last couple of decades of the 18th century to the early years of the 20th century. One of the early stories is a flight from my own home city, Chester. Thomas Baldwin recorded his flight in Airopaidia: Containing the Narrative of a Balloon Excursion from Chester, the eighth of September, 1785. The book does not have the air of a rigorous history of ballooning, it introduces technical aspects but not systematically. It is impressionistic to a degree, and as a result a rather pleasant read. For Holmes the artistic and social impact of balloons are as important as the technical.

In the beginning there was some confusion as to the purposes to which a balloon might be put, early suggestions included an aid to fast messengers who would stay on the ground to provide but use a small balloon to give them “10 league boots”, there were similar suggestions for helping heavy goods vehicles.

In practice for much of the period covered balloons were used mainly for entertainment – both for pleasure trips but also aerial displays involving acrobatics and fireworks. Balloons were also used for military surveillance.  Holmes provides chapters on their use in the American Civil War by the Union side (and very marginally by the Confederates). And in the Franco-Prussian war they were used to break the Prussian siege of Paris (or at least bend it). The impression gained though is that they were something like novelty items for surveillance. By the time of the American Civil War in the 1860’s it wasn’t routine or obvious that one must use balloon surveillance, it wasn’t a well established technique. This was likely a limitation of both the balloons themselves and the infrastructure required to get them in the air.

Balloons gave little real utility themselves, except in exceptional circumstances, but they made a link to heavier-than-air flight. They took man into the air, and showed the possibilities but for practical purposes generally didn’t deliver – largely due to their unpredictability. To a large extent you have little control of where you will land in a balloon once you have gone up. Note, for example, that balloons were used to break the Prussian siege of Paris in the outbound direction only. A city the size of Paris is too small a target to hit, even for highly motivated fliers.

Nadar (pseudonym of Gaspard-Félix Tournachon), who lived in Paris, was one of the big promoters of just about anything. He fought a copyright battle with his brother over his, adopted, signature. Ballooning was one of his passions, he inspired Jules Verne to starting writing science fiction. His balloon, Le Géant, launched in 1863 was something of a culmination in ballooning – it was enormous – 60 metres high but served little purpose other than to highlight the limitations of the form – as was Nadar’s intent.

From a scientific point of view Falling Upwards covers James Glaisher and Henry Coxwell’s flights in the mid-nineteenth century. I was impressed by Glaisher’s perseverance in taking manual observations at a rate of one every 9 seconds throughout a 90 minute flight. Glaisher had been appointed by the British Association for the Advancement of Science to do his work, he was Superintendent for Meteorology and Magnetism at the Royal Greenwich Observatory. With his pilot Henry Coxwell he made a record-breaking ascent to approximately 8,800 meters in 1862, a flight they were rather lucky to survive. Later in the 19th century other scientists were to start to identify the layers in the atmosphere. Discovering that it is only a thin shell – 5 miles or so thick which is suitable for life.

The final chapter is on the Salomon Andrée’s attempt to reach the North Pole by balloon, as with so many polar stories it ends in cold, lonely, perhaps avoidable death for Andrée and his two colleagues. Their story was discovered when the photos and journals were recovered from White Island in the Artic Circle, some 30 years after they died.

Falling Upwards is a rather conversational history. Once again I’m struck by the long periods for technology to reach fruition. It’s true that from a technology point of view that heavier-than-air flight is very different from ballooning. But it’s difficult to imagine doing the former without the later.

Aug 23 2014

Book review: Greenwich Time and the Longitude by Derek Howse

greenwich_timeI am being used as a proxy reader! My colleague drj, impressed by my reviewing activities, asked me to read Greenwich Time and the Longitude by Derek Howse, so that he wouldn’t have to.

There was some risk here that Greenwich Time and the Longitude would overlap heavily with Finding Longitude which I have recently read. They clearly revolve around the same subjects and come from the same place: the National Maritime Museum at Greenwich. Happily the overlap is relatively minor. Following some brief preamble regarding the origins of latitude and longitude for specifying locations, Greenwich Time starts with the founding of the Royal Observatory at Greenwich.

The Observatory was set up under Charles II who personally ordered it’s creation in 1675, mindful of the importance of astronomy to navigation. The first Royal Astronomer was John Flamsteed. Accurate measurement of the locations of the moon and stars was a prerequisite for determining the longitude at sea both by lunar-distance and clock based means. Flamsteed’s first series of measurements was aimed at determining whether the earth rotated at a constant rate, something we take for granted but wasn’t necessarily the case.

Flamsteed is notorious for jealously guarding the measurements he made, and fell out with Isaac Newton over their early, unauthorised publication which Newton arranged. A detail I’d previously missed in this episode is that Flamsteed was not very well remunerated for his work, his £100 per annum salary had to cover the purchase of instruments as well as any skilled assistance he required which goes some way to explaining his possessiveness over the measurements he made. 

Greenwich Time covers the development of marine chronometers in the 18th century and the period of the Board of Longitude relatively quickly.

The next step is the distribution of time. Towards the middle of the 19th century three industries were feeling the need for precise timekeeping: telegraphy, the railways and the postal service. This is in addition to the requirements of marine navigators. The first time signal, in 1833, was distributed by the fall of a large painted zinc ball on the top of the Greenwich observatory. Thereafter, strikingly similar balls appeared on observatories around the world.

From 1852 the time signal was distributed by telegraphic means, and ultimately by radio. It was the radio time signal that ultimately brought an end to the publication of astronomical tables for navigation. Britain’s Nautical Almanac, started in 1767, stopped publishing them in 1907 – less than 10 years after the invention of radio.

With the fast distribution of time signals over large distances came the issue of the variation between local time (as defined by the sun and stars) and the standard time. The problem was particularly pressing in the United States which spanned multiple time zones. The culmination of this problem is the International Date Line, which passes through the Pacific. Here the day of the week changes on crossing the line, a problem discovered by the very first circumnavigators (Magellan’s expedition in 1522), identified when they reached travellers who had arrived from the opposite direction and disagreed on the day of the week. I must admit to being a bit impressed by this, I can imagine it’s easy to lose track of the days on such an expedition.

I found the descriptions of congresses to standardise the meridian and time systems across multiple nations in the 1880s rather dull.

One small thing of interest in these discussions: mariners used to measure the end of the day at noon, hence what we would call “Monday morning” a mariner would call “the end of Sunday”, unless he was at harbour – in which case he would use local time! It is from 18th century mariners that Jean Luc Picard appears to get his catchphrase “Make it so!”, this was the traditional response of a captain to the officer making the noon latitude measurement. The meridian congresses started the process of standardising the treatment of the day by “civilians”, mariners and astronomers.

The book finishes with a discussion of high precision timekeeping. This is where we discover that Flamsteed wasn’t entirely right when he measured the earth to rotate at a constant rate. The earth’s rotation is showing a long term decrease upon which are superimposed irregular variations and seasonal variations. And the length of the year is slowly changing too. Added to that, the poles drift by about 8 metres or so over time. It’s testament to our abilities that we can measure these imperfections but somehow sad that they exist.

The book has an appendix with some detail on various measurements.

Not as sumptuous a book as Finding Longitude it is an interesting read with a different focus. It has some overlap too with The History of Clocks and Watches by Eric Bruton.