Category: Book Reviews

Reviews of books featuring a summary of the book and links to related material

May 27 2012

Book Review: The History of Clocks & Watches by Eric Bruton

The-History-of-Clocks-Watches-by-Eric-BrutonEarlier, it was telescopes, now I’m on to clocks! Here I review Eric Bruton’s book “The History of Clocks & Watches”. I came to it via an edition of the Radio 4 programme “In Our Time” on the measurement of time (here). The book was originally published in 1979, the edition I read was from 2002. I mention this because there is some evidence that the text has not been fully updated.

1 Earliest clocks

The book starts with a slightly cursory look at the use of the sun to measure time, and mentions briefly the use of candles. The first mechanical clocks were based on water, and in Europe were used as timekeepers in monastic communities. No direct physical evidence appears to remain for these clocks, although there are detailed descriptions in books from the time such as Su Sung’s 1092 “New Design for a (Mechanised) Armillary (sphere) and (celestial) globe”. They appear to have been used widely in ancient times. The sandglass, superior to the water clock because of the flow properties of sand when compared to water, first appears in illustrations in 1337.

2 Advent of clockwork

“Clockwork” clocks started to appear started to towards the end of the 13th century, they were found in monasteries to call the monks to prayer. The key components of a clock are a mechanical oscillator, initially a bar with weights at the end know as a foliot, an “escapement” to allow motion coupled to the mechanical oscillator to work a display and a driving force to keep the oscillator going. In these early clocks falling weights provided the driving force. The first escapements were known as “verge escapements” and were in use until 1800, several hundred years after they were introduced. In fact it took an awfully long time for mechanical clockwork to replace solar clocks. Improvements to timepieces are in the quality of the mechanical oscillator: making it insensitive to pressure and temperature, and making sure the driving force and display train interferes minimally with the going of the oscillator.

3 Domestic Clocks

The first spring driven clocks appeared around 1430, the spring enables a rather more compact clock but the problem is the power it generates varies with how far it is unwound, this problem was addressed using a fusee which moderates the output power, apparently adapted from siege engines where it is used in reverse to enable men to wind up catapult style devices. Another trick is to use the spring only in a small part of its unwinding.

4 European mechanical clocks

It was not until 1657 that Christiaan Huygens introduced the pendulum as the oscillator for clocks, which produces a big improvement in accuracy – it actually becomes relevant for a timepiece to have a minute hand. Huygens made repeated contributions to the development of the clock, although he had a clockmaker implement his ideas in much the same manner as Robert Hooke had Thomas Tompion implement his ideas.

5 The Time at sea

As early as 1598 Philip III of Spain had offered a reward for a method to find the longitude, it was a well-recognised problem well before the Board of Longitude was created in England to provide a prize for its solution. John Harrison and his marine chronometers for determining the longitude are covered in some detail, extending beyond his life to cover the developments of other clockmakers including John Arnold, Thomas Mudge, Thomas Earnshaw and Pierre Le Roy. Harrison is famous for his dispute with Nevil Maskelyne, the Astronomer Royal, and something of an embodiment of the Board of Longitude that funded his work but it seems that clockmakers of the time were disputatious with each other and the Board.

The fields of astronomy and timekeeping are tied together, many early clocks went to great lengths to show astronomical information such as the phases of the moon. Even in the 20th century the most precise mechanical clocks were made for astronomical use, in the past Thomas Tompion was renowned for his precision timepieces supplied to the Royal Observatory. Whilst Christiaan Huygens made revolutionary advances in both clock design and telescopes. There is a relationship between dividing a quadrant, a device for measuring angles in astronomy, accurately into increments and dividing the gear wheels of a clock accurately to position the teeth.

6 The development of the watch

Personal timepieces date from the late 15th century, in fact prior to this people carried personal sundials or even used themselves as the pointer in a simple sun clock. The challenge with a watch is to produce a compact timepiece, meaning small parts, which is robust to the forces that being carried around all the time exert. I have to say here that the watches that Abraham-Louis Breuguet made at the end of the 18th century are absolutely gorgeous (see here, for example).

7 Mass production

I found it surprising the degree of precision achieved in the pre-Industrial age in the manufacture of timepieces, but then I also found pre-Industrial lens grinding semi-miraculous. This probably says more about me then anything else but perhaps the message is that bespoke precision pre-dated the Industrial Revolution whose strength was in standardising components, introducing continuous workflows and making use of less skilled labour. At points in time specific areas of England, France, Germany, Switzerland and the US were predominant centres of manufacture with the US leading the way in mass production but the Swiss picking it up in Europe.

8 The Technological Age

The 19th century saw the arrival of trains and telegraph, these bring the need to standardise time and the means to do it. Scheduling of trains means that standardising time is to some degree a safety issue, the adoption of time zones in the US in 1876 was also driven by the railways. The adoption of Greenwich Mean Time occurred in 1880, the Greenwich Observatory had been providing a time single in the form of a dropping ball since 1833. The telegraph enabled such time signals to be distributed more broadly, and used automatically. Electricity was also incorporated in the running of the clock, the 1921 Synchronome electromechanical clock providing the ultimate in accuracy until the introduction of quartz and atomic timekeepers.

9 Watches for the people

The final part of the book covers the reduction of cost to mass produce watches which all could afford, this process includes simplifying the mechanisms and sacrificing accuracy where possible. It highlights the development of digital watches in the 1970s where the prevailing mechanism for testing the quality of electronic components was to sell them and see how many were returned!

For my own amusement I present the following table which presents the accuracy of various landmark timepieces in standardised form, the first two entries are from this wikipedia article whilst the remainder are from the book:

pre-1657 15 minutes per day 328500 seconds/year
1657 Christiaan Huygens 15 second per day 5475 seconds/year
1766 Pierre Le Roy 7.5 seconds over 46 days 60 seconds/year
1921 Synchronome Fractions of a second per year 0.5 second/year
1955 Atomic clock 1s in 3000 years 0.00033 seconds/year

Coincidently the improvement in accuracy for successive entries in this table is 100-fold.

The book is heavily illustrated with pictures of timepieces, diagrams of mechanisms and engravings of workshops. I rather like this, but in places it feels like you’ve seen an image before in relation to an earlier section of the book. Although the book is logically arranged, in fact I borrowed the logic to structure this post, the presentation of how clock mechanisms work is disjoint, and scattered throughout the book.

My follow on reading from this book is on Christiaan Huygens, he isn’t a central character here but he just turns up in so many different places!

Footnotes

  • My Evernotes on the book are here.
  • The Breguet at the Lourve exhibition looks interesting (here)

May 12 2012

Book review: Measure of the Earth by Larrie D. Ferreiro

Measure-of-the-EarthThis post is a review and summary of Larrie D. Ferreiro’s book “Measure of the Earth” which describes the French Geodesic Mission to South America to measure the length of a degree of latitude at the equator. The action takes place in the 2nd quarter of the 18th century, the Mission left France in 1735 with the first of its members returning to Europe in 1744.

The book fits together with The Measure of All Things by Ken Alder, which is about the later French effort to measure a meridian through Paris at the turn of the Revolution in order to define the metre, The Great Arc by John Keay on the survey of India and Map of a Nation by Rachel Hewitt on the triangulation survey of the United Kingdom.

The significance of the measurement was that earlier triangulation surveys of France had indicated that the earth was not spherical, as had pendulum measurements made by Jean Richer in Guyana in 1671 which showed a pendulum there ran 2:28 slower there than in Paris. A Newtonian faction believed that the earth was flattened at the poles, its rotation having led to a bulging at the equator. A Cartesian school held that the earth was flattened around the equator and bulged at the poles, this was not a direct result of work by Rene Descartes but seems to have been more a result of scientific nationalism. Spoiler: the earth is flattened at the poles.

From a practical point of view a non-spherical earth has implications for navigation – ultimately it was found that polar flattening would lead to a navigational error of approximately 20 miles in a trans-Atlantic crossing although at the time of the Mission it was believed it could have been as much as 300 miles. Politically the Mission provided an opportunity for the French to form an alliance with the Spanish, and to get a close look at the Spanish colonies in South America which had provided huge wealth to Spain over the preceding 200 years. Ferreiro provides a nice overview of the L’Académie des Sciences under whose aegis the mission was conducted,and of the Comte de Maurepas, French minister of the navy and sponsor of the Mission.

The core members of the Geodesic Mission were Pierre Bouguer, Charles-Marie de La Condamine, and Louis Godin they were accompanied by Spanish Naval cadets Antonio de Ulloa y de la Torre-Guiral  and Jorge Juan y Santacilia. Other members were Joseph de Jussieu (doctor and botanist), Jean-Joseph Verguin (engineer and cartographer), Jean-Louis de Morainville (draftsman and artist), Theodore Hugo (instrument maker), Jean-Baptiste Godin des Odonais and Jacques Couplet-Viguier.

Louis Godin, an astronomer, was the senior academician and nominal leader of the mission. Pierre Bouguer, was a mathematician, astronomer and latterly geophysicist: as well as the measurement of the degree of latitude he also attempted to measure the deflection of a plumb-line by the mass of a mountain – an experiment which Nevile Maskelyne was to conclude successfully in 1775, I wrote about this here. Bouguer also wrote a treatise on ship building whilst away in South America. Charles-Marie de La Condamine could best be described as an adventurer although he was also a competent mathematician and geographer, it was his more lively writing on life in South America which would have a bigger impact on their return to Europe.

The scheme for the determination of the length of a degree is to measure the length of a meridian (a line of longitude) close to the equator by triangulation, making a ground measurement baseline to convert the angular measurements of the triangulation survey into distances and a second baseline to confirm your workings; the latitudes of the ends of the triangulation survey are determined astronomically by measuring the positions of stars. I’ve read of this process before, the new thing I learnt was the method for aligning up your zenith sector with the meridian – which I’m tempted to try at home.

These measurements were done in the area around Quito, in modern Ecuador (named after the equator), the endpoints of the survey were at Quito in the north, close to the equator and Cuenca approximately 200 miles south. During the survey, through the Andes, the team scaled peaks as high as Mont Blanc (and suffered altitude sickness for their troubles) which would not be climbed for another 50 years. The survey was repeated in the early years of the 20th century and even then it took 7 years – the same length of time as the original survey, due to the transport difficulties presented by the terrain.

The work of measuring the meridian was made more difficult by the journey to get there (which took the best part of a year), the terrain and conditions when they got there (mountainous and cloudy), the poor leadership of Godin, local political machinations and the mother country cutting them loose financially. Ferreiro makes a lot of Godin’s poor leadership, some of which is justified – he spent Mission money on prostitutes and regarded the Mission funds as his own purse. Frequently the Mission split into two groups, one containing Bouguer and La Condamine and the other Godin – sometimes this is quite appropriate, in duplicating measurements for consistency whilst on other occasions it is simply fractiousness.

To a degree the Mission was scooped by measurements made above the Arctic Circle in Lapland, this mission was also promoted by the L’Académie des Sciences, led by Pierre Maupertuis (a rival of Bouguer) and Anders Celsius. It completed its work in 6 months, well before the Geodesic Mission had finished their work, discovering that the poles of the earth were flattened. However, doubts remained over the results and the full determination required the data from the equator. Bouguer presented this on his return to France, to great acclaim, showing that the earth was flattened by 1 part in 179 (later measurements showed that the flattening is actually smaller at 1 part in 298).

The Mission spawned a wide range of publications by its members, covering not only the geodesic component of the work but also regarding life and nature in South America. Ferreiro credits La Condamine’s work in particular has setting the context of how South America was viewed for quite some time after the mission. The Spanish officers also made in impact an highlighting colonial misrule back to their home country. Arguably the international collaborative elements of the Mission set the scene for the measurements of the transit of Venus later in the 18th century.

Ferreiro makes a comparison between the French Geodesic Mission, which was centrally run by the state and the British Longitude Prize, which although state funded was privately executed, implying that the former was superior. It’s not clear to me whether he’s engaging in a degree of hyperbole here, since the Mission was to some degree an organisational car-crash and was in large part funded from La Condamine’s own purse at the time. Furthermore, L’Académie des Sciences also awarded prizes – having copied the British government in this and the Royal Society was from the outset a very internationally oriented organisation. So the picture as Ferreiro presents it is something of an over-simplification.

I found the book very readable, its clearly based on a large quantity of primary source material and covers a great deal beyond the simple mechanics of the Geodesic measurements.

Footnotes

My Evernotes on the book are here.

Apr 17 2012

Book Review: Stargazers by Fred Watson

41W3OswkqxL._SS500_This post is a review of “Stargazers:The Life and Times of the Telescope” by Fred Watson. It traces the history, and development of the telescope from a little before its invention in 1608 to the present day.

The book begins its historical path with Tycho Brahe, a Danish astronomer who lived 1546-1601. He built an observatory, Uraniborg, on the Danish island of Hven in view of his patron, King Frederick II of Denmark. Brahe’s contribution to astronomy were the data which were to lead to Johannes Kepler’s laws of planetary motion and ultimately Isaac Newton’s laws of gravitation. On the technical side his observatory represented the best astronomy of pre-telescope days with the use of viewing sights, his Great Armillary with it axis aligned with that of the earth and graduated scales to measure angles. Watson also cites him as a first instance of a research director running a research institute – alongside the observatory he ran a print works to disseminate his results.

The telescope was first recorded in September of 1608, when Hans Lipperhey presented one to Prince Maurice of Nassau in the Netherlands. Clearly it was a device of its time since in very short order several independent inventions appeared, Galileo constructed his own version which led to his publication of “The Starry Messenger” in 1610 which reports his observations using the device. The telescope grew out of the work of spectacle makers; there are some hints of the existence of telescope-like devices in the latter half of the 16th century but these are vague and unsubstantiated. Roger Bacon and Robert Grosseteste both conceived of a telescope-like device in the 13th century, around the time the first spectacles were appearing. Although there are a few lenses from antiquity there is no good evidence that they had been used in telescopes.

The stimulus for the creation of the first telescopes seems to have been a combination of high quality glass becoming available, and skilled lens grinders. The lens making requirements for telescopes are much more taxing than for spectacles. The technology required is not that advanced, if you look around the web you’ll find a community of amateur astronomers grinding their own lenses and mirrors now using fairly simple equipment, typically a turntable with a secondary wheel which produces linear motion for the polishing head back and forward across the turning lens blank. The most technologically advanced bit is probably captured in the first step: “acquire your glass blank”.

Through the 17th century refracting telescopes were built of ever greater length in an effort to defeat chromatic aberration which arises from the differential refraction of light as a function of wavelength (colour) – long focal length lenses suffered from less chromatic aberration than the shorter focal length ones which would allow a shorter telescope. Johannes Hevelius made telescopes of 46m focal length (physically the telescope would be a little shorter than this), mounted on a 27m mast; Christiaan Huygens dispensed with the “tube” of the telescope entirely and made “aerial telescopes” with even longer focal lengths, up to 64m.

It was known through the work of Alhazen in the 10-11th century, and others, that reflecting, curved-mirrors could be used in place of lenses. A telescope constructed with such mirrors would avoid the problem of chromatic aberration. However, the polishing tolerances for a reflecting telescope are four times higher than that of a lens. Newton built the first model reflecting telescope in 1668 but no-one was to repeat the feat until John Hadley in 1721.

Theoretical understanding of telescopes developed rapidly in the 17th century both for refracting and reflecting telescopes, indeed for reflecting telescopes there were no fundamental advices in the theory between 1672 and 1905. The problem was in successfully implementing theoretical proposals. Newton claimed that chromatic aberration could not be resolved in a refracting telescope, however he was proved wrong by Chester Hall Moor in 1729, and somewhat controversially by John Dollond in 1758 who was able to obtain a patent despite this earlier work (which was defended aggressively by his son) – the trick is to build compound lenses comprised of glass of different optical properties.

Also during the 18th century the construction of reflecting telescopes became more common, William Herschel started building his own reflecting telescopes in 1773 with the aid of Robert Smith’s “Compleat system of opticks”. Ultimately he was to build a 40ft (12m) telescope with a 48 inch (1.2m) mirror in 1789, supported by a grant from George III. During his lifetime Herschel was to discover the planet Uranus (nearly called George in honour of his patron), numerous comets and nebulae. At the time “official” astronomy was more interested in the precise measurement of the positions of stars for the purpose of navigation. Herschel was to be followed by Lord Rosse with his 1.8m diameter mirror telescope built in 1845 at Birr Castle, this has been recently restored (see here). He too was interested in nebula and discovered spiral galaxies.

During the 19th century there were substantial improvements in the telescope mounts, with engineers gaining either an amateur or professional interest (men such as James Nasmyth and Thomas Grubb). Towards the end of the century photography became important, which placed more exacting standards for telescope mounts because to gain maximum benefit from photography it was necessary to accurately track stars as they moved across the sky to enable long exposure times. This is also the century in which stellar spectrography became possible with William Huggins publishing the spectra of 50 stars in 1864. Léon Foucault invented the metal coated glass mirror in 1857 which were lighter and more reflective than the metal mirrors used to that point. As the century ended the largest feasible refracting telescopes with lens diameters of 1m were just around the corner, above this size a lens distorts under its own weight reducing the image quality.

In 1930 Bernhard Schmidt designed a reflecting telescope which avoided the problem of aberrations away from the centre of the field of view making large field of view “survey” telescopes practicable. As a youth in the 1970s I learnt of the 200-inch (5 metre) Hale telescope at Mount Palomar, since then space telescopes able to see in the infra-red and ultra-violet as well as the visible have escaped the distortion the atmosphere brings; adaptive optics are used to counteract atmospheric distortion for earthbound telescopes and there are “distributed” interferometric telescopes which combine signals from several telescopes to create a virtual one of unfeasible size.

Watson mentions briefly radio telescopes and in the final chapters speculates on developments for the future and gravitational lensing – natures own telescopes built from galaxies and spread over light years.

I enjoyed “Stargazers” as a readable account of the history of the telescope which left me with a clear understanding of its principles of operation and the technological developments that enabled its use, it also provides a good jumping off point for further study.

Footnotes

My Evernotes for the book are here, featuring more detailed but slightly cryptic notes and links to related work.

Apr 06 2012

Book Review: Adapt by Tim Harford

adaptThis is a review of “Adapt: Why Success Always Starts With Failure” by Tim Harford which puts forward the thesis that “trial and error” is the only way forward for complex endeavours to succeed.

Opening up to trial and error is divided into three tasks:

  • Providing scope for variation in what you do;
  • Establishing whether or not a variant has been successful;
  • Making sure that you have systems in place to cope with failure.

Each of these tasks is illustrated with a wide range of real-life examples: using the Iraq War to highlight the difficulties of running “trial and error” inside control structures that are designed to take in information, channel it to the top of the organisation and provide a channel back from the top to the bottom. Donald Rumsfeld, apparently, would not refer to the “insurgents” as “insurgents” so hobbling the US’s ability to fight an “insurgency”.

Alongside these major case studies are smaller ones, such as on Jamie Oliver’s school dinners which showed that feeding children healthy food at primary level led to measurably better outcomes in education and attendance than comparable groups not within the scheme, you can see the study here.

There is also a section on using a carbon tax to address anthropogenic climate change, this fits in as a way of making selection possible by providing a simple measure of “success”. Harford is scathing of the ”Merton Rule” which demands that new build of above a certain size generate 10% of their electricity onsite by renewable means. As put by Harford this means installing capacity rather than demonstrating capacity which has lead to the use of dual fuel systems (nominally able to take renewable fuel) that are ultimately only used with non-renewables so providing no benefit at all.

The Piper Alpha and Three Mile Island accidents are provided as examples of the importance of being able to fail safely, they didn’t or rather Piper Alpha didn’t – arguably Three Mile Island just about failed safely. This was linked to failings in the financial system where large organisations, such as Lehman Brothers failed in a matter of hours with administrators scrabbling around frantically to come up with a controlled-landing plan. This is failure at large scale, but there is also coping with failure at the personal scale. For example, using “Deal or No Deal” as a model system in which contestants can “lose” which changes their estimations of risk for subsequent play for the worse.

One issue with “trial and error” is that the proponents of any method are often so convinced of the value of their method that they feel it immoral to subject anyone to an “inferior” alternative in order to conduct a trial. This is highlighted with a story about Archie Cochrane, pioneer of the randomised control trial in medical studies. He had been running a study on coronary care, comparing home-based care to hospital care. This had met with some opposition, with medics insisting that the home-based arm of the trial was unethical because it was bound to be inferior. When results started to come in it turned out that one branch of the trial was inferior to the other – Cochrane misled his colleagues into believing it was the home-based arm that was inferior – they demanded that it should be closed down but were rather silent when he revealed that it was in fact the hospital-based arm of the trial that was inferior!

Harford also discusses funding for research, in particular that blue-skies research could not be valued because the outcomes were so uncertain, highlighting the success of the Howard Hughes Medical Institute which funds speculative biomedical research in the US. What he goes on to say is that the use of prizes is a way out of this impasse. Using as an example the Longitude Prizes, his presentation plays up the friction between Harrison and the Board of Longitude. The Academie Des Sciences also ran prizes but until recently the method had been out of favour for approaching 200 years. The recent revival has included things like the DARPA challenges for self-driving cars, Ansari X Prize, the Bill and Melinda Gates Foundation prize for vaccines and Netflix’s film selection challenge. These have been successful, however it’s difficult to see them finding more general favour in the academic community since the funding is uncertain and appears only after researchers have expended resources rather than receiving the resource before doing the work.

From a practical point of view “trial and error” happens in the private sector, if not within companies then between. In the voluntary sector it has taken some hold, for me some of the more compelling examples were by the “randomistas” studying the effectiveness of aid programmes. In the public sector “trial and error” is more difficult: there is less scope for feedback on the success of a trial – you can’t meaningfully count customers through the door, or profits made, so there is a need for proxy measures. Furthermore, the appearance of failure carries a high price in the political sphere. This is not to say it shouldn’t happen, simply that “trial and error” face particular challenges in this area.

I like the central thesis of the book, it fits with my training as a scientist; my field allows for more direct experimentation than a randomised trial but the principle is the same. It also has pleasing parallels with biological evolution, which Harford explicitly draws. The book is well referenced, in fact I hit the end unexpectedly as I was reading on a Kindle – I couldn’t “see” the length of the end notes!

Mar 25 2012

Book Review: The Great Arc by John Keay

TheGreatArcThis is a review of “The Great Arc: The Dramatic Tale of How India Was Mapped and Everest Was Named” by John Keay. This book does exactly what it says in the lengthy subtitle: describe the Great Triangulation Survey of India which was conducted in the first half of the 19th century.

It fits together with “Map of a Nation” by Rachel Hewitt and “The Measure of All Things” By Ken Alder. The former describes the detailed mapping of the United Kingdom by the Ordnance Survey, whilst the later describes the measurement of the Paris meridian by Méchain and Delambre. Of the three surveys the French one had been completed first at the beginning of the 19th century whilst the mapping of the UK was going on at the same time as the Indian survey.

The book is centred around the Great Arc survey originally proposed by William Lambton at the beginning of the 19th Century. Lambton’s aim was primarily to measure a meridian (a line of longitude), in the same manner as the Paris meridian in order to gain more information on the shape of the earth (geodesy). For his sponsors in England and the administration of India the survey served as a military and commercial exercise. Military action is often a spur to survey, since getting your troops and their equipment from point A to point B and ensuring they prevail over any forces they come across on the way is a high-value activity which is greatly assisted by the provision of accurate maps. Surveying is also invaluable when you are planning infrastructure such as roads, canals and railways.

The survey came a time when the British relationship with the area now known as India was changing from a trading one based on outposts to one in which the British took territory militarily. The Triangulation Survey was not exhaustive, it comprised a central spine (The Great Arc) running along the 78th meridian up through the tip of the Indian peninsular to the edge of the Himalayas with regular “cross-bars” running from West to East, towards the north an array of parallel meridians were also measure. (You can see a map here). The aim was to use this survey to constrain further local surveys.

The Great Arc survey was a great endeavour, taking 40 or so years in total, after Lambton died in 1823 George Everest took on the job of leading the project. Lambton seems to have been a pleasant sort of chap who went a little native, disappearing from the view of his sponsors. Everest, on the other hand, appeared to be a complete git – being abusive to most of his subordinates and apparently also winding up his superiors.

Much of the activity in the book is in common with that which took place during the surveys of France and the United Kingdom. Laying out base-lines: distances measured directly on the ground by means of rods or chains used to pin down the distances in the “triangulation” which is a collection of angular measurements at the vertices of an array of triangles. Once again the precision is impressive, two 7 mile baselines measured out 200 miles apart agree with the triangulation measurement to within a few inches. Angular measurements were made using a theodolite, Keay labels the one used in India as the “Great Theodolite”, which I thought was a term reserved for the Ramsden device used in the UK (we can’t all have a Great Theodolite!).

The Indian survey presented different challenges in the form of the wildlife (tigers, scorpions etc) but also disease. The rate of attrition amongst the surveyors, particularly as they traversed jungle was terrible. The book is not explicit about figures but in the later stages of the survey something like a thousand men were involved and a couple of hundred of those died of disease. Lambton and later Everest both suffered from recurring bouts of malaria.

The “discovery” of Mount Everest and the tallest peaks in the Himalayas was somewhat incidental to the main thrust of the survey. It had become clear in the first decade or so of the 19th century that the Himalayas were the tallest mountains in the world but their precise height was uncertain. Political difficulties with Nepal, their location far from the sea and their immense size meant determinations were poor. Indeed at the time of the beginning of the survey the height of Mont Blanc in Europe was only know to within a thousand feet or so of its currently accepted value. It wasn’t until 1856, after the Great Arc had been completed and Andrew Scott Waugh had taken over the survey that Mount Everest (known at the time as Peak XV) was measured and Waugh proposed Everest be its name. (Everest is apparently pronounced Eve-rest rather than Ever-est, and the man himself was very particular about this).

Put beside “Map of a Nation” and “The Measure of All Things”, “The Great Arc” is a nice, brief introduction to the theme of triangulation surveys and geodesy which covers measuring the height of mountains in a bit more detail than the other two.

The Great Arc survey, along with the French meridian survey fit together with the earlier French Geodesic Mission to Peru by Condamine and Bouger around 1735, which is described in “Measure of the Earth” by Larrie G. Ferreiro – I’ve added this to my wish list.

Footnotes

You can see my Evernotes on The Great Arc here.