Tag: history of science

Book review: Eye of the Beholder by Laura J. Snyder

A return to more traditional fare with snyderEye of the Beholder by Laura J. Snyder. This is a collective biography of Johannes Vermeer and Antonie van Leeuwenhoek who were both born in Delft in 1632. Vermeer, a painter, lived for 43 years and Leeuwenhoek most famous as a microscopist lived for 91 years. Alongside the stories of their lives, Snyder also talks about the events in Delft, and the wider Netherlands, and the evolving understanding of optical phenomena that is relevant to both painting and microscopy.

A theme of the book is the idea that Vermeer and Leeuwenhoek knew each other, and possibly knew each other quite well – with their expertise feeding in to each other. This is a link that Snyder has discovered, and is somewhat circumstantial since there is no direct evidence of correspondence between the two men. The main evidence for the assertion is that Leeuwenhoek acted as executor to Vermeer’s estate, some have seen this as no particular evidence since Leeuwenhoek was a public official who might be expected to take on this role. But he only did this for four people, three of whom had known personal links. The other piece of evidence is that they lived within a few hundred yards of each other in a relatively small city and shared common interests in optical phenomena so very likely knew each other, they both knew Constantijn Huygens. In some ways the existence of a personal link is not important, rather the drawing together of technologies of camera obscura and microscopes as new ways to see and understand the world.

I note that as someone who has worked both as a microscopist and in photorealistic computer graphics this book is particularly close to my interests, and strikes a chord with me. One of the challenges of microscopy is understanding what on earth you are seeing, and photorealistic computer graphics brings in to sharp focus the mechanisms by which an image is formed. Even now, three hundred years after Vermeer and Leeuwenhoek, specialists in these fields will have undergone a personal journey of discovery where they sought out the thing they were looking for down the eyepiece of a microscope (possibly spending more time than they’d admit focused on the top surface of the coverslip rather than the sample). In photorealistic computer graphics rendering forgetting to include a light in their model and pointed the virtual camera in the wrong direction, leading to a completely black image are not uncommon beginners mistakes.

In the 17th century the Netherlands was a hotbed of scientific discovery, trade and art – the so-called Golden Age which had started in 1588 and came to an end in 1672 with the Franco-Dutch War. Despite much scientific work, the Netherlands were not to have a scientific society like the the Royal Society until the 18th century. Private art was commonplace in 17th century Netherlands, Snyder associates this with religious sensibilities – as a protestant nation the Dutch did not favour extravagant public, religious art but compensated with art in their own homes. On average each Delft household had two paintings. Also relevant to the story is the fact that the Dutch had only recently started adopting surnames in the 17th century, and it seems in the beginning they were often chosen thoughtfully which is alien to the modern mind for whom surnames are generally a given.

In Delft the biggest event of the book is the "Delft Thunderclap" in 1654, an explosion at a gunpowder store that killed over a hundred people and injured thousands more.

The camera obscura is the focus of the artist side of the story, it had been invented some time around the 13th century, and it was to join other optical aids for artists. A camera obscura is basically a box with a hole in it (originally room sized), where an image of what lies outside the box is projected onto a wall. Hyperrealism though the use of the camera obscura was something of a passing fad, Da Vinci had been scornful of the use of such aids, and there usage was something of a trade secret for artists. By the 17th century the camera obscura had evolved from a simple room with light entering through a hole to a system, possibly even a portable box featuring mirrors and lenses. The camera obscura allowed the artist to capture the geometry of a scene by copying the projected image (indeed camera obscura were also used by surveyors). What’s more by separating the image from the scene it served as a tool to better understand how light interacted with materials. Vermeer’s work shows signs of his use of the camera obscura from the late 1650s.

This is not to diminish the skill of a painter, it struck me that Vermeer’s style had elements in common with the much later Impressionists with subtle uses of colour and line being used to give the impression of a scene rather than painting and exact replica to the canvas.

Vermeer was to die in 1675 at the age of only 43, 1672 "Rampjaar" had left him close to destitute as the art market collapsed, and he had 11 children to provide for. He left behind only 45 paintings from his 20 year career.

The microscope is the focus of Leeuwenhoek’s side of the story, the microscope had been invented in the early part of the 17th century but was not much used until much later in the century with Robert Hooke’s magnificent book Micrographia showing what it could achieve. Leeuwenhoek’s microscopes are quite different from those we use today, they are simple spherical lenses mounted in metal plates smaller than playing cards. Leeuwenhoek’s skill was persistent and careful observation over a period of 40 or so years, reported to the Royal Society in London in over 300 letters. He discovered microbes, red corpuscles in blood, as well as the wriggling tails of sperm amongst much else. He studied the inner workings of things rather than just the surface appearance, as Robert Hooke had done. His preparation of samples equals those prepared today. I recall that Leeuwenhoek was long ignored in the history of microscopy because his work was so much in advance of anything for years after his death and he kept his methods secret, although Snyder makes no mention of this so perhaps I mis-remember.

I really liked this combination of biography, national history and history of ideas. Snyder’s style is warm and clear, I also enjoyed her earlier "The Philosophical Breakfast Club".

Book review: The clock and the camshaft by John Farrell

camshaftThe clock and the camshaft by John Farrell is the story of technology through the Middle Ages which went on to support the Renaissance and the Scientific Revolution.

The book is structured by invention, and although some of the inventions are technologies as we would generally understand them there are also chapters on universities and monasteries, and languages. Each chapter looks at the ancient antecedents of a technology, where there is one, before looking at its place in the Middle Ages and how it played on to the Renaissance that followed. The antecedents are typically in the Roman Empire, China and the Middle East. The overall structure of the book is reminiscent of the technology “trees” one finds in a certain sort of computer game (Civilisation/Age of Empires).

There was a huge drop in population after the end of the Roman Empire in Europe in the 5th century CE until the 9th or 10th century. People no longer lived in towns or cities, and the art of building with stone appears to have been lost across much of Europe.

Food is a core concern at anytime and there were a couple of technological developments during the Middle Ages which helped here. The plough, used in the Mediterranean, was developed to better suit heavy Northern European soils. Horses were adopted to pull ploughs through the development of horse shoes and suitable harnesses.

In the Middle East water wheels were used in irrigation, from several centuries BCE. In Northern Europe irrigation was not quite such a concern but water wheels for power, in the first instance for milling wheat were important. This is not a simple technological development, for most individuals working the land it is convenient to hand mill wheat for your own consumption – a water powered mill is not worth the effort in maintenance or in initial capital outlay. This is where feudalism and monasteries get involved, feudal barons and monasteries can build and maintain a mill economically and they have subjects whose grain can be milled, for a price. Feudal masters obliged their subjects to use their mills, and pay a tariff to do so and under threat of punishment if they were found to be milling their own grain.

Once you have something that goes round and round, driven by a water or wind mill, then the next step is something that goes forwards and backwards. Or, more prosaically, converting rotation motion to linear motion. This might be to power a saw, or more often, to hammer things. Hammering things is important in the production of cloth (fulling), paper (pulping), and metal (crushing ore).Who would have thought hammering things was so important?

Paper is another key technology, the earliest writing is found in clay which was then superseded by papyrus – produced almost exclusively in Egypt. For rough notes codexes were used – parallel thin pieces of wood tied together. In Europe, after the fall of the Roman Empire, parchment made from the skins of goats or calves was used but this required a lot of dead animals. Meanwhile in China paper made from rags was being developed. This innovation was developed in Europe too, this arrival was key for new businesses. Now tradespeople could write things down relatively freely, critical for banking, and important in other businesses.

The challenge with clocks is to allow an power source to release its energy at a steady rate, this is done using an “escapement” mechanism. The first mechanical clocks were recorded in Europe towards the end of the 13th century.

Having forgotten how to build with stone at the end of the Roman Empire the cathedrals of the Middle Ages, built mostly in the 12th and 13th centuries were a sign that the skill of building with stone had been rediscovered. They were an evolution of Roman designs for grand buildings which allowed for much greater light through the insertion of windows. They followed the stone built castles of the Norman period around 1000 CE. Cathedrals are a rather more complex building than a castle but castles provided a good training ground.

Religion provided the impetuous for collecting manuscripts from the Arab world, during the 12th and 13th centuries with a view to improving their astronomic determinations of the date of Easter. Along the way they collected other manuscripts, returning to Spain and Italy to translate them.

Eye lenses were introduced in the first half of the 12th century, and appeared to evolve from glass used to display relics. There were antecedents of lenses found in ancient Egypt even back to the Bronze Age. The Venetians were early specialists in glass making, founding a guild in 1320. There was also expertise north of the Alps in Nurembourg but the quality of ground lenses dropped from 1500 with the first telescope makers towards the end of the century making their own lenses rather than buying them.

Monasteries, and monks, played an important role in carry knowledge across the Middle Ages after the fall of the Roman Empire. They were also important players in the material world, taking the part of a sort of feudal lord in some instances. Universities were in some senses a spin off from the collision between the Church and the Secular state, they arose originally as a place to study law – a topic which came to the fore in disputes between the Church and secular states over which had legal authority. Universities and monasteries are both examples of legal entities which were not people, an important innovation in law.

The book finishes with a chapter on lodestones which lead to the development of compasses for navigation, astrolabes and boats. Astrolabes were designed for astronomical measurement but also served as timekeepers, their design fed into the layout of the clock face. Boats were another technology which evolved as it moved north, the key innovation was switching to a skeleton-based design where the keel and ribs were laid down first, and then planks attached to them.

I liked this little book, much of what I’ve read in the history of science covers a later period – from the 17th century onward – The Clock and the Camshaft provides useful background, and is also very readable.

Book review: Science City by Alexandra Rose and Jane Desborough

science_cityOn Twitter I hang out with a load of historians of science, and this has lead me to Science City: Craft, Commerce and Curiosity in London 1550-1800 by Alexandra Rose and Jane Desborough. This is an edited volume which accompanies the new Linbury Gallery at the Science Museum, combining objects from the Science Museum, King George III collection and the Royal Society. This book touches on many of the books I’ve read previously on the Board of Longitude, the transit of Venus, surveying and map making.

The main part of the book is four roughly chronological chapters covering the development of an instrument making industry in London, the Royal Society, public displays of science, and global expeditions. At the beginning of the period covered by the book, 1550, London was not a particularly notable city – it was a quarter the size of Paris and only twice the size of Norwich – England’s second city at the time. It had no universities, in fact it wasn’t to have a university until 1826.

The instrument trade in London started with a need to fulfil the requirement for “mathematical instruments” for surveying, gunnery and architecture. It was boosted by immigrants from the Low Countries fleeing persecution. In 1571 5% of the London population were “strangers” – born outside of England. These immigrants were not unwelcome, foreign manufactured goods were often seen as better quality which caused some resentment in the Guilds. Skills were developed and maintained by apprenticeships. These were typically found by personal contacts in the 16th century, there was no advertising of positions. Science City traces some apprenticeship “lineages”. In the early days there was no specific Guild for instrument making.

The second chapter brings in the Royal Society founded in 1666. As well as the instrumental needs of Robert Hooke, its Curator of Experiments, it stimulated a wider trade in instruments. The members of the Royal Society were keen to replicate experiments, or do their own experiments to share with the Society (or at least keen enough to spend money on instruments). Variants of the air pump demonstrations Hooke did were still being done 40 years later. The Royal Society put London at the centre of a network of scientific correspondents, and to some degree defined the way to be a scientist that maintains to this day.

In the ensuing years public science became a popular entertainment. Popularisers of science needed instruments to ply their trade. By this point in the first half of the 18th century there are 300 instrument makers in London, their business is divided into mathematical instruments (theodolites, sextants and the like), optical instruments (microscopes and telescopes) and philosophical instruments (those used to demonstrate physical principles). Its interesting to see the birth of branding at this point, makers were known by their shops signs and for clarity they would typically use a consistent image across there pamphlets and shopfront (rather than simply words). Examples include Benjamin Martin’s “spectacle” logo, and Edward Culpeper’s crossed daggers.

The final chapter covers the second half of the 18th century, this is at a time where the Ordnance Survey is founded alongside triangulation surveys with France. The chapter speaks to the global reach of London in trade and in science. This is the time of the Board of Longitude which was founded, making its major awards to John Harrison for his chronometer in the second half of the 18th century. The expeditions to view the transit of Venus in 1769 were also significant – the Royal Society petitioned the King to fund an expedition to Tahiti, this was accompanied by other expeditions which led to a requirement for moderately standardised instrumentation to make the measurements. London was able to supply this demand.

Science City finishes with interviews with an instrument maker (Joanna Migdal), the President of the Royal Society and the Lord Mayor of London (also a trustee of the Science Museum). The first of these I found really interesting I wish there were photos of the sundials the interviewee made, you can find some here on their website. Migdal’s work, individual, handcrafted items, is probably in the character of the instrument making of this book but differs from the typical instrument ecosystems these days.

The book is rather smaller than I expected but it is beautifully illustrated, more a bedside table than a coffee table book. I enjoy these catalogues of museum exhibitions more than the exhibitions themselves. In the gallery you are pushed for time and space, reading the descriptions can be difficult cross-referencing to other things you have read is impractical. A book makes it a more comfortable process but just lacks the immediacy of seeing the objects “in-person”.

Book review: The Pope of Physics by Gino Segrè and Bettina Hoerlin

fermiThe Pope of Physics by Gino Segrè and Bettina Hoerlin is the biography of Enrico Fermi. I haven’t read any scientific biography for a while and this book on Enrico Fermi was on my list. He is perhaps best known for leading the team that constructed the first artificial nuclear reactor as part of the Manhattan Project. As a lapsed chemical physicist I also know him for Fermi surfaces, Fermi-Dirac statistics, and the Fermi method. Looking on Wikipedia there is a whole page of physics related items named for him.

Fermi was born at the beginning of the 20th century, his parents were born before Italy was unified in 1870 when illiteracy was not uncommon and people typically stayed close to home since travel quickly involved crossing borders.

Fermi was identified as something of a prodigy whom a friend of his father, Adolfo Amidei, took under his wing and smoothed his path to Pisa Scuola Normale Superior. As I sit here in in a mild lockdown I was bemused to note that the entrance exams Fermi took were delayed by the 1918 Spanish Flu pandemic. At Pisa Fermi learned largely under his own steam, at the time physics was not an important subject – the Pisa Scuola had five professors in physics and only one in physics. Fermi graduated at the top of his class.

After Pisa Fermi fell into the path of Orso Mario Corbino, a physicist, politician and talented organiser who set about helping Fermi to build a career in physics. At the time a new quantum physics was growing, led primarily by young men such as Pauli, Dirac, Heisenberg and Schrödinger who was a little older. Fermi met them on a scholarship to Göttingen in Germany. He later went to Leiden on a scholarship where he met Ehrenfest, and Einstein who was very taken with him. This was preparation for building a new physics capability in Italy.

The fruits of this preparation were a period in the mid-1930s which saw Fermi and his research group at Rome University invent a theory of nuclear decay which revealed the weak nuclear force and postulated the existence of the neutrino (this theoretical work was Fermi’s alone). The wider research group studied the transmutation of elements by slow neutron bombardment. This work was to win Fermi the 1938 Nobel Prize for Physics.

This research led on directly to the discovery of nuclear fission and the chain reaction which became highly relevant as Fermi fled Italy to the US with his wife on the eve of the Second World War. Many of Fermi’s friends, including his wife Laura, were Jewish. Fermi steered clear of politics to a large degree, he benefitted from the patronage of Mussolini but was no fascist enthusiast. The Italian uses of chemical weapons in Ethopia and, ultimately, the racial laws of the late 1930s which expelled Jews from their positions drove him from the country. He had visited the US a number of times in the early 1930s and had little trouble finding a position at Columbia University.

The route to the atomic bomb was not quick and smooth in the early years of the war, a number of physicists had noted the possibility of the fission bomb and attempted to warn politicians of its potential. This all changed when the Americans joined the war, following the Japanese attack on Pearl Harbour.

Building an atomic bomb presented a number of scientific challenges which Fermi was well-placed to address, primary amongst these was building “Critical Pile 1” the first system to undergo a self-sustaining nuclear chain reaction. It was constructed, slightly surreptitiously, in a squash court at Chicago University. It was built there as a result of a dispute with the contractor who was due to build it a little outside Chicago, at Argonne.

The “critical pile” demonstrated two things: firstly that chain reactions existed, and secondly it provided a route to producing the nuclear isotopes required to produce a bomb. It still left the question of how to purify the isotopes, and the question of how to produce a critical mass fast enough to cause a worthwhile explosion.

Fermi would go on to help in the Manhattan Project at Hanford and then Los Alamos where he held a position combining both universal scientific consultancy and administration, or at least organisation.

It is difficult to talk about Fermi’s strengths as a physicist – he had so many – he is almost unique in being both a top flight experimentalist, and theoretician. This is the great divide in physics, and people who are talented in both fields are rare. He was also clearly an excellent teacher, as well as undergraduate teaching and writing a high school physics book he supervised 7 students who would go on to earn Nobel Prizes in physics. Alongside this he was clearly personable.

Fermi died in November 1954 a little after his 53rd birthday, leaving in his wake a large number of prizes, buildings and discoveries as a memorial.

I found The Pope of Physics highly readable, the chapters are quite short but focused.

Book Review: The Egg & Sperm Race by Matthew Cobb

egg_and_spermI follow quite a few writers on Twitter, and this often leads me to read their books. The Egg & Sperm Race by Matthew Cobb is one such book. It traces the transition in thinking on the reproduction of animals, including humans, which occurred during the second half of the 17th century.

Prior to this we had some pretty odd ideas as to how animals reproduced, much of it carried over from the Ancient Greeks. Ovid and Virgil both claimed that you could make bees by burying a bull with its horns protruding from the ground, waiting and then cutting off the horns to release the bees! This confusion is not surprising, the time between mating and the appearance of young is quite long, and the early stages of the process are hidden by being very small, and deep inside animals.

A random “fact” I cannot help but repeat is that Avicena wrote that “a scorpion will fall dead if confronted with a crab which a piece of sweet basil basil has been tied”. I wonder sometimes with quotes such as these whether they are a result of mistranslation, or a bored scribe. The point really is such ideas were not discounted out of hand at the time. The Egg & Sperm Race starts with a description of da Vinci’s copulating couple which is beautiful but wrong – da Vinci connects the testicles to the brain – these structures do not exist.

The heart of the action in The Egg and Sperm Race is in the Netherlands, in England the Royal Society showed relatively little interest in generation aside from some experiments on the spontaneous generation of cheese mites. The Chinese and Arab scholars who had worked in various fields showed little interest in generation.

The central characters are Jan Swammerdam, Niels Stensen (known as Steno) and Reinier de Graaf, who met in Leiden at the university in the early 1660s when they were in their early twenties. Swammerdam and Steno were a little older than de Graaf and were close friends. Soon after meeting in Leiden they visited Paris where they continued to build contacts in the scientific community.

In understanding generation a first step was to realise that all animals came from other animals of the same species, and that this meant mating between two animals of the same species. Steno went to Italy and worked with Francesco Redi’s whose experiments were key to this, he checked exhaustively that insects did not arise from the putrefaction of material. Swammerdam was also interested in insects, classifying four different types of invertebrate development and showing that in moths traces of the adult form are found in the caterpillar. At the time it was not clear that the larval stage and the adult were the same species.

A second step was to realise that all animals came from eggs of some sort, William Harvey –  of blood circulation fame – did experiments in this area but although he stated this conclusion but it was not well-supported by his experiments. In the period at the beginning of this book, the role of the ovary was not understand. Steno carried out dissections on fish both those that laid eggs, and those that gave birth to live young from this he concluded that the ovaries were the source of eggs and asserted that this was the case for humans as well. This idea rapidly gained acceptance.

The discovery of the human egg, and its origins in the ovary, was the subject of a dispute between de Graaf and Swammerdam on priority. The Royal Society decided in favour of van Horne with whom Swammerdam had worked on the dissection and illustration of female reproductive anatomy. To modern eyes the written record of the dispute, in letters, and publications is surprisingly personal. De Graaf died at the age of 32 just prior to the Royal Society decision. It was a difficult time in the Netherlands with the country at war with England and France with France troops invading parts of the country.

Leeuwenhook cast a spanner into the works with his microscopical studies, he observed spermatozoa but not the female egg and as a result became a “spermist”, believing that life came from the sperm in contrast to the “ovists” who believed life came from the egg. We now know that they are both right. The human egg was not observed until 1826 by von Baer. And I have to mention Spallazani’s experiments on frogs wearing taffeta shorts, demonstrating that male sperm was required to fertilise the female egg.

The final chapter covers events from the end of the 17th century or a little later to present day. Linneaus’s classification work, and Darwin’s theory of evolution follow on from some of the core realisations of this earlier period. Neither Linneaus’ work nor Darwin’s work make much sense if you don’t believe that animals (and plants) grow from eggs/seeds which came from the same species. It wasn’t until von Baer’s work in the early 19th century that the female egg was observed.