Tag Archive: history of science

Aug 13 2017

Book review: The Comet Sweeper by Claire Brock

thecometsweeperA return to women in science in this post where I review The Comet Sweeper: Caroline Herschel’s Astronomical Ambition by Claire Brock, a biography of a woman who discovered comets and nebulae and published a catalogue of astronomical objects in the later years of the 18th century. For scientists the name “Herschel” will not be unknown. Caroline Herschel’s brother William discovered Uranus, and was paid as an astronomer by King George III. Her nephew, John was also well known as a scientist. However, relatively little has been written about Caroline.

The Comet Sweeper is based substantially on the autobiographical writing of Herschel. However, she was sufficiently well-known at the time to be referenced elsewhere, and indeed later in her life was bestowed with various honours and medals for her astronomical work.

Herschel was born in Hanover in 1750, her father Isaac was a musician and very much a self-taught man – something he passed on to Caroline. Anna, her mother, gets a less than sympathetic treatment from her daughter and consequently this book. For her early years Anna treated Caroline as a servant, and stopped her education as soon as it appeared it would help her leave the Herschel household in Hanover. She was finally given a means of escape when her brother, William, invited her to Bath to work in music with him in 1771. She had no previous training in music and put herself assiduously to learning what she needed to know. William Herschel was earning up to £400 per year from music lessons and the like when he invited his sister to join him. It seems that Caroline became a significant musician in her own right, at least until her brother dragged her into astronomy.

This is something of a theme through the book, Caroline Herschel is clearly very capable and when given the opportunity can excel in whatever she turns her hand to. But the choices she has are limited. In the first instance her mother controls what she can do, then her brother – switching her from music to astronomy with little regard for her own wishes.

In astronomy Herschel started by assisting her brother in the workshop – at the time, to get the best telescope, you built them from scratch yourself. She supported him in his observations but she also carried out observations on her own. The “sweeping” of the title is the systematic scanning of the night sky with a telescope to identify static features such as stars and nebulae but more specifically to find comets. To a degree the discovery of nebulae was incidental to the main task of finding comets, nebulae were easily confused with comets so recording their locations was an essential part of finding comets. The Herschel’s work followed, but only by a few years, the publication of Charles Messier’s first catalogue of diffuse celestial objects in 1774.

As well as discovering comets and nebulae Herschel was also responsible for publishing Catalogue of Nebulae and Clusters of Stars in 1798, which built on the earlier work of Flamsteed. Ultimately this became the New General Catalogue of stars. Amateur astronomers will know this work, Messier’s catalogue provides information on the 100 or so most prominent objects whose identifying numbers are prefixed with an M- beyond this are the NGC objects – from the New General Catalogue which is the descendant of Herschel and Flamsteed’s catalogue.

Herschel was honoured in her own lifetime with a gold medal from the Royal Astronomical Society, as well as honorary membership and medal from the King of Prussia, at the age of 96. She was the first woman to be published in Philosophical Transactions the journal of the Royal Society. These awards did come until quite late in her life although she was paid £50 per annum by King George III as an assistant to her brother. He was paid rather more, £200, but notably rather less than he earned as a musician.

I found the broader insight that The Comet Sweeper gave into the lives of Georgian women was interesting. Women did not have formal positions within the scientific community of the time but they contributed as wives, sisters, daughters. At the time there was little in the way of formal, paid, scientific community – it was very much a gentleman’s club but there was a place for women in it although not necessarily of equal status.

This was to change later in the 19th century when science became institutionalised, as a result women were excluded by, for example, not being able to receive degrees or even attend lectures at university. 

The Comet Sweeper is not a long book, it is readable and casts an interesting light on women in science in Georgian England and the specific contributions of Caroline Herschel.

Aug 01 2017

Book review: Inventing Temperature by Hasok Chang

inventing_temperatureMy next read is more academic in character, Inventing Temperature: Measurement and Scientific Progress by Hasok Chang. As an undergraduate chemical physics student, temperature was important to me. On the chemistry side of the equation, increasing the temperature of a reaction by 10 degrees doubles its rate. Statistical mechanics forms the core of chemical physics, and this is very much about temperature and equilibrium. In a laser, light is emitted when population inversion is achieved which some describe as negative temperature. It’s fair to say that measuring temperature is one of the core activities of any physical scientist, even if all you are trying to do is keep your experiment at a fixed temperature.

The book starts with a discussion of the fixed points used in thermometry. For the familiar Celsius temperature scale these are (crudely) the melting point of ice and the boiling point of water. The temperature difference between these two fixed points is divided into 100 equal divisions, and the scale can be extrapolated above and below these fixed points.

But this isn’t so easy, it isn’t necessarily a given that ice always melts and water always boils at the same temperature – superheating and supercooling are things that will dog you, particularly if you take great care with your experiments! In a theoretical sense we now know that melting and boiling happen at fixed temperatures under fixed conditions. Experimentally exactly how you set your water boiling and your ice melting can change the temperature at which they appear to melt or boil. In the early days of temperature measurement these questions were all consuming and took many years to resolve.

Another question is “what does it mean to measure temperature"?”. Chang proposes a Principle of respect in the development of measurement and also epistemic iteration. That is to say that the development of the measurement of temperature is guided – respects – our perception of temperature but is not dominated by it. Sometimes our perception of temperature is wrong, epistemic iteration allows us to correct that perception or at least make our measurement correct. If you’d like an example of an incorrect temperature perception try testing the same water having run your hand under hot and cold taps – we perceive a different temperature even when there is no difference.

The next step in the process of measuring temperature is trying to make a linear scale which does not depend on the precise nature of the thermometer you use. This is difficult to achieve without having a clear idea of what temperature is. Linked to this is the problem of what the best “working fluid” is for your thermometer – although we are familiar with mercury and alcohol thermometers, from a scientific point of view “air thermometers” are the best behaved. To a 20th century physicist this is unsurprising but in the late 18th and early 19th century this was not obvious. Furthermore, air was more difficult to work with.

After considering the problem of the linearity of the temperature scale Chang turns to temperatures far above and below the fixed points of the scale, below where mercury freezes and above where glass melts. The challenge at low temperatures was attaining low temperatures, the challenge at high temperatures was finding any sort of device that could survive and keep working at high temperatures. For a long time a pyrometer invented by Josiah Wedgewood was used which relied on measuring the shrinkage of clay pellets as a measure of temperature. Joining this temperature scale to one measured at lower temperatures with conventional thermometers was hard.

Finishing the specific sections on measuring temperature is a chapter on theoretical considerations, focusing on the work of Joule and Thomson. Who established an absolute temperature scale, and under what circumstances a gas could be used to measure such a scale.  Epistemic iteration plays a part here as the combatants need to find a concrete system to demonstrate an abstract principle, and show that their concrete system is close to being abstract!

The book ends with two chapters on more general matters in the history and philosophy of science. The first of these is on Chang’s view of how science progresses. The second is on what Chang calls “complementary science”, how the history and philosophy of science could lead to an increase in scientific knowledge. In my view scientific progress would likely be improved if students were taught better in the history of their subject.

I found this book fascinating, as far as I can recall I came across a much abbreviated form of some of this work during my A-levels when I wasn’t really able to appreciate the scale of the challenge in the now simple act of measuring temperature. Once at university measuring temperature was a given but I gained a more sophisticated understanding of what temperature meant – an understanding that was based on theories developed in the late 19th century.

Nov 17 2016

Book review: The Invention of Science by David Wootton

inventionofscienceBack to the history of science with The Invention of Science by David Wootton which covers the period of the Scientific Revolution.

Wootton’s central theme is how language tracked the arrival of what we see as modern science in a period from about 1500 to 1700, and how this modern science was an important thing that has persisted to the present day. I believe he is a little controversial in denying the ubiquity of the Kuhnian paradigm shift and in his dismissal of what he refers to as the postmodern, “word-games” approach to the history of science which sees scientific statements as entirely equivalent to statements of beliefs.This approach is exemplified by Leviathan and the air-pump by Steven Shapin and Simon Schaffer which gets several mentions.

Wootton argues contrary to Kuhn that sometimes “paradigm shifts” happen almost silently. He also points out that Kuhn’s science is post-Scientific Revolution. One of the silent revolutions that he cites is the model of the world. “Flat-earth” in no way describes the pre-Colombus model of the world which originated from classical Greek scholarship. In this theoretical context the sphere is revered and the universe is built from the four elements: earth, wind, fire and water. The model for the “earth” is therefore a variety of uncomfortable attempts to superimpose spheres of water and earth. The Ancients got away with this because in Classical times the known world did not cover enough of the earth’s sphere to reveal embarrassing discrepancies between theory and actuality. With Colombus’s “discovery” of America and other expeditions crossing the equator and reaching The Far East over land these elemental sphere models were no longer viable. The new model of the earth which we hold to today entered quietly over the period 1475 to 1550. 

Colombus’s “discovery” also marks one of the key themes for the book, the development of new language to describe the fruits of scientific investigation. Prior to Colombus the idea of an original discovery was poorly expressed in Western European languages, writers had to specifically emphasise that they were the first to find something or somewhere out rather than a having a word to hand that expressed this. Prior to this time, Western European scholarship was very much focused on the “re-discovery” and re-interpretation of the lost wisdom of the Ancients. Words like “fact”,”laws” (of nature), “theories”, “hypotheses”, “experiment” and “evidence” also evolved over this period. This happened because the the world was changing, the printing press had arrived (which changed communication and collaboration entirely). Machines and instruments were being invented, and the application of maths was widening from early forms of banking to surveying and perspective drawing. These words morphed to their modern meanings across the European languages in a loosely coupled manner.

Experimentation is about more than just the crude mechanics of doing the experiment, it is about reporting that work to others so that they can replicate and extend the work. The invention of printing is important in this reporting process. This is why alchemy dies out sometime around the end of the 17th century. Although alchemy has experiments, clearly communicating your experiments to others is not part of the game. Alchemy is not a science, it is mysticism with scientific trappings.

As a sometime practising scientist all of these elements of discovery, facts, evidence, laws, hypotheses and theories are things whose definitions I take for granted. They are very clear to me now, and I know they are shared with other working scientists. What The Invention of Science highlights was that there was a time when these things were not true.

The central section of the book finishes with some thoughts on whether the Industrial Revolution required the Scientific Revolution on which to build. The answer is ultimately “yes”, although the time it takes is considerable. It flows from the work of Denis Papin on a steam digester in the late 17th century to Newcomen’s invention of the steam engine in the early 18th century. Steam engines don’t become ubiquitous until much later in the 18th century. The point here is that Papin’s work is very much in the spirit of a “academic” scientist (he had worked with Robert Boyle), whereas Newcomen sits in the world of industrial engineering and commerce.

I’ve not seen such an analysis of language in the study of the Scientific Revolution before, the author notes that much of this study is made possible by the internet. 

The editor clearly had a permissive view of footnotes, since almost every page has a footnote and more than a few pages are half footnote. The book also has endnotes, and some “afterthoughts”. Initially I found this a bit irritating but some of the footnotes are quite interesting. For example, the Matses tribe in the Amazon include provenance in their verb forms, using the incorrect verb form is seen as a lie. In my day to day work with data this “provenance required” approach is very appealing.

The Invention of Science is very rich, and thought provoking and presents a thesis which I had not seen presented before, although the “facts” of the Scientific Revolution are well known. I’m off to read Leviathan and the air-pump partly on the recommendation of the author of this book.

Dec 17 2015

Book review: The Invention of Nature by Andrea Wulf

inventionofnatureThe Invention of Nature by Andrea Wulf is subtitled The Adventures of Alexander von Humboldt – this is his biography.

Alexander von Humboldt was born in Berlin in 1769, he died in 1859. The year in which On the Origin of Species was published. He was a naturalist of a Romantic tendency, born into an aristocratic family, giving him access to the Prussian court.

He made a four year journey to South America in 1800 which he reported (in part) in his book Personal Narratives, which were highly influential – inspiring Charles Darwin amongst many others. On this South American trip he made a huge number of observations across the natural and social sciences and was sought after by the newly formed US government as the Spanish colonies started to gain independence. Humboldt was a bit of a revolutionary at heart, looking for the liberation of countries, and also of slaves. This was one of his bones of contention with his American friends.

His key scientific insight was to see nature as an interconnected web, a system, rather than a menagerie of animals created somewhat arbitrarily by God. As part of this insight he saw the impact that man made on the environment, and in some ways inspired what was to become the environmentalist movement.

For Humboldt the poetry and art of his observations were as important as the observations themselves. He was a close friend of Goethe who found him a great inspiration, as did Henry David Thoreau. This was at the time when Erasmus Darwin was publishing his “scientific poems”. This is curious to the eye of the modern working scientist, modern science is not seen as a literary exercise. Perhaps a little more effort is spent on the technical method of presentation for visualisations but in large part scientific presentations are not works of beauty. 

Humboldt was to go voyaging again in 1829, conducting a whistle-stop 15,000 mile 25 week journey across Russia sponsored by the government. On this trip he built on his earlier observations in South America as well as carrying out some mineral prospecting observations for his employers.

Despite a paid position in the Prussian court in Berlin he much preferred to spend his time in Paris, only pulled back to Berlin as the climate in Paris became less liberal and his paymaster more keen to see value for money.

Personally he seemed to be a mixed bag, he was generous in his support of other scientists but in conversation seems to have been a force of nature, Darwin came away from a meeting with him rather depressed – he had not managed to get a word in edgewise!  

I’m increasingly conscious of how the climate of the time influences the way we write about the past. This seems particularly the case  with The Invention of Nature. Humboldt’s work on what we would now call environmentalism and ecology are highly relevant today. He was the first to talk so explicitly about nature as a system, rather than a garden created by God. He pre-figures the study of ecology, and the more radical Gaia Hypothesis of James Lovelock. He was already alert to the damage man could do to the environment, and potentially how he could influence the weather if not the climate. There is a brief discussion of his potential homosexuality which seems to me another theme in keeping with modern times.

The Invention of Nature is sub-subtitled “The Lost Hero of Science”, this type of claim is always a little difficult. Humboldt was not lost, he was famous in his lifetime. His name is captured in the Humboldt Current, the Humboldt Penguin plus many further plants, animals and geographic features. He is not as well-known as he might be for his theories of the interconnectedness of nature, in this area he was eclipsed by Charles Darwin. In the epilogue Wulf suggests that part of his obscurity is due to anti-German sentiment in the aftermath of two World Wars. I suspect the area of the “appropriate renownedness of scientific figures of the past” is ripe for investigation. 

The Invention of Nature is very readable. There are seven chapters illustrating Humboldt’s interactions with particular people (Johann Wolfgang von Goethe, Thomas Jefferson, Simon Bolivar, Charles Darwin, Henry David Thoreau, George Perkins Marsh, Ernst Haeckel and John Muir). Marsh was involved in the early environmental movement in the US, Muir in the founding of the Yosemite National Park (and other National Parks). At first I was a little offended by this: I bought a book on Humboldt, not these other chaps! However, then I remembered I actually prefer biographies which drift beyond the core character and this approach is very much in the style of Humboldt himself.

Sep 21 2015

Book review: The Values of Precision edited by M. Norton Wise

valuesofprecisionThe Values of Precision edited by M. Norton Wise is a collection of essays from the Princeton Workshop in the History of Science held in the early 1990s.

The essays cover the period from the mid-18th century to the early 20th century. The early action is in France and moves to Germany, England and the US as time progresses. The topics vary widely, starting with population censuses, then moving on to measurement standards both linear and electrical, calculating methods and error analysis.

I’ve written some notes on each essay, skip to the end of the bullet points if you want the overview:

  • The first article is about the measurement of population, mainly in pre-revolutionary France. This was spurred by two motivations: firstly, monarchs were increasingly seeing the number of their subjects as a measure of their power and secondly, there was a concern that France was experiencing depopulation. In the 17th century the systematic recording of births, deaths and marriages was mandated by royal direction. In the period after this populations were either estimated from a count of “hearths” or from the number of births. The idea being that you could take either of these indirect measures and multiple them by some factor to get a true measure of population.
  • The second article is by Ken Alder, he of “The Measure of All Things” and is another trip to revolutionary France and their efforts to introduce a metric system of measurement. The revolutionary attempt failed but the system of standards they created prevailed in the middle of the 19th century but not without some effort. Alder highlights the resistance of France to metrification, and also how the revolution bred a will to introduce a rational system based on natural measurements rather than a physical object created by man. He also discusses some of the benefits of the pre-metric system: local control, the ability for workers to take a cut without varying price, connection to effort expended/quality. This last because land was measured in terms of the amount of grain used to seed it or the area one person could harvest in a day – this varies with the quality of the land.
  • Jan Golinski writes on Lavoisier (again from France at the turn of the Revolution) regarding “exactness” and its almost political nature. Lavoisier made much of his exact measurements in the determination of the masses of what are now called hydrogen and oxygen in producing a known mass of water. This caused some controversy since other experimenters of the time saw his claims of exactness in measurement to be mis-used in supporting his theory for chemical reactions. There were reasons to be sceptical of some of his claims, he often cited weighed amounts to more significant figures than were justified by the precision of his measurements and there are signs his recorded measurements are a little too good to be true. These could be seen as the birthing pains of a new way of doing science which didn’t just apply to chemical measurements of the time, but also to surveying and the measurement of population. These days the inappropriateness quoting of more significant figures than are justified by the measurement is drummed into students at an early age.
  • Next we move from France to Germany and a discussion of the method of least squares, and the authority of measurements by Kathryn M. Olesko. Characters such as Legrendre and Laplace had started to put the formal analysis of error and uncertainty in measurement on the map. This work was carried forward by Gauss with the method of least squares, essentially this says that the “true” value of a measurement is that which minimises the squared difference of all the measurements made of that value. It is an idea related to probability, and it is still deeply embedded in how we make measurements today and also how we compare measurement to theory. In common with events in France, the drive for better measurement came in Germany with a drive to standardise weights and measures for the purposes of trade. The action here takes place in the first half of the 19th century.
  • The trek through the 19th century continues with Simon Schaffer’s essay on the work in England and Germany on electrical units with a particular view to establishing whether the speed of light and the speed of propagation of electromagnetic waves were the same. This involved the standardisation of units of electrical resistance. It was work that went on for some time. Interesting from a practicing scientists point of view was the need for the bench scientist and instrument makers to work closely together.
  • The next chapter is a step away from the physical sciences with a look at life insurance and the actuarial profession in the first half of the 19th century. Theodore Porter describes the attitude of this industry to precision and calculation, noting that they fended off attempts to regulate the industry too tightly by arguing that there business could not be reduced to blind calculation. The skill, judgement and character of the actuary was important.
  • The Image of Precision is about Helmholtz’s work on muscle physiology in around 1850, he used an apparatus which showed the extension of a muscle graphically following stimulation, and measured the speed of nerve impulses using similar methods. The graphical method was in some senses less precise than an alternative method but it was a more compelling explanatory tool and provided for better understanding of the phenomena under study.
  • Next up is a discussion of the introduction of so-called “direct-reading” ammeters and voltmeters by Ayrton and Perry in around ~1870. This was an area of some dispute, with physicists claiming that determinations of volts and amps be made by reference to the basic units of length, time and mass. Ayrton and Perry were interested in training electrical engineers whose measurements would be made in environments not conducive to these physicist-preferred measurements. Not conducive in both a technical sense (stray magnetic fields, vibration and so forth) nor in the practical sense (an answer within 1 percent in 10 minutes was far superior to one within 0.5 percent in 2 hours).
  • As we approach the end of the book we learn of Henry Rowland, and his diffraction gratings, made at John Hopkins university. Rowland had toured Europe, and on his return set to making high quality diffraction gratings to measure optical spectra. This is a challenging technical task, to be useful a diffraction grating needs many very closely spaced lines of the same profile. Rowland sent out his diffraction gratings for a nominal price, making no profit, but did not reveal the details of his methods. It took many years for his work to be better, and even longer yet for better diffraction gratings to be available generally.
  • The collection finishes with the construction of mathematical tables, starting with a somewhat philosophical discussion of the limits of calculation but moving onto more pragmatic issues of the calculation and sharing tables. The need for these tables came original with the computationally intensive calculations for determining the longitude by the method of lunar distances. The 19th century saw the growth in mathematical analysis in a range of areas, spreading the need to make mathematical tables. Towards the end of the century machine calculation was used to help build these tables, and do the analysis they supported. Students of my generation will likely just about remember using tables of trigonometric and other functions, these days in my practical work they are entirely replaced by computer calculations done on demand.

There is a lot in here which will speak to those with a training in science, physics in particular. The techniques discussed and the concerns of the day we will recognise in our own training. The essays hold a slight distance from practitioners in this arts but that brings the benefit of a different view. Core to which is the way in which precision in measurement is a social as well as technical affair. To propagate standards of measurement requires the community to build trust in the work of others, this does not happen automatically.

I like this style of presentation, each essay has its own character and interest. The range covered is much larger than one might find in a book length biography, and there is a degree of urgency in the authors getting their key points across in the space allocated.

In this book the various chapters do not overlap in their topics and cover a substantial period in time and space with the editor providing some short linking chapters to tie things together. All in all very well done.

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