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Sunday, 27 September 2020

Circus acrobats and strong men in 1859

This is one of a series of entries are drawn from chapter 7 of my book, Mr Darwin's Incredible Shrinking World, and they all deal with life in that era. For background on the book, see the first entry in the series, Life in 1859, but if you just want to see the others, use the tag 1859, which appears at the end of each entry.

The Romans had wanted their bread and circuses, the folk of 1859 would settle for just a circus, but it was rather less barbaric than the Roman namesake. The “equestrian circus” began in London in 1786, but 1859 was the year that the flying trapeze was added to the bill. The world’s first flying trapeze circus act was performed on November 12 at the Cirque Napoléon in Paris by Jules Léotard, 21, who had practiced at his father’s gymnasium in Toulouse. He wore the daring (for that period) tights which still carry his name.

A whole series of daring young men followed him, but few were as daring or showy as Charles Blondin, the tightrope walker. Starting on June 30, Blondin made 21 crossings during the summer on a rope 1100 feet long stretched 170 feet above the boiling waters of the Niagara Falls, from Prospect Park on the United States side to the Canadian side. 
On August 17 he carried his manager across the gorge on his back. The trip lasted 42 minutes and included 42 rest stops. Scientific American was scathing: “We did not suppose that two such fools existed on this hemisphere. The idea of such a thing is enough to congeal the blood.”

Doctor George Winship, a 25-year-old physician who trained in Cambridge Massachusetts could raise himself by either little finger until he was half a foot above it. He could also raise 200 lb by either little finger and lift 926 pounds dead weight, without the aid of straps or belts, said The Times

Closer to home, Scientific American used the same figures a week earlier, suggesting that both journals drew from the same original source or press release, as there was no time for the American material to have crossed the Atlantic.

The American account says Winship was due to give a lecture in Boston, but fainted twice. He attributed this to the atmosphere being close and impure, though others thought it was because he had not spoken in public before. His lecture was on physical education, but the aptly named the Boston Atlas reported that the strong man proved an infant. Winship seems to have disappeared from public notice thereafter.

For his own pleasure and the amusement of others, a gentleman in Liskeard, Cornwall fashioned himself a suit made solely from 670 rat skins, collected over three and a half years. It included neckerchief, coat, waistcoat, trousers, tippet, gaiters, shoes and even a rat hat.

It was a measure of the way people were being urbanised that dogs were now seen more as companion animals than as work assistants. The world’s first dog show was held at Newcastle-upon-Tyne in June, while Birmingham held another show in November. To this day, Britain’s National Dog Show is organised by the “Birmingham Dog Show Society (founded 1859)”. The Battersea Dogs’ Home was established in 1860.

There was a poultry and pigeon show at London’s Crystal Palace in January. No doubt a few scientists who knew Darwin’s ideas would have dropped in to view the displays, because the selected breeds of birds were central to Darwin’s arguments about what could be achieved by selection of another sort, natural selection. Perhaps they took in a theatrical show while they were in town, but perhaps they did not, because many still thought the theatre lacked propriety.

Thursday, 17 September 2020

Sporting fashions in 1859

This is one of a series of entries are drawn from chapter 7 of my book, Mr Darwin's Incredible Shrinking World, and they all deal with life in that era. For background on the book, see the first entry in the series, Life in 1859, but if you just want to see the others, use the tag 1859, which appears at the end of each entry.

To most Americans and Canadians today, cricket is a mystery, but Abraham Lincoln attended a cricket match between Chicago and Milwaukee in 1859, and a professional All England cricket team toured Canada and the USA during the year, playing five matches, the first overseas tour in any sport. Taking a cricket team to the US back then was not as bizarre as it sounds from today’s perspective.

In 1859, cricket was very popular in the mid-Atlantic states, in Boston and the New England factory towns, but it could also be seen in Baltimore, Savannah, New Orleans, Cleveland, Cincinnati, and even San Francisco, a total of perhaps 300 or 400 clubs.

Cricket even inspired American inventions. In March, M. Doherty of Boston patented a cricket bat that would not jar or bruise, but which would send the ball further. The blade had a wooden shell filled with cork or similar material, while the handle was hollow and contained a strip of whalebone, but in 1859, the baseball craze started to bite, and soon cricket would be eclipsed.

The writing was on the wall for cricket in September, when the ball game for the Massachusetts state championship caused enough interest for several railroads to issue excursion tickets to Boston’s Agricultural Fair Grounds.

Many new sports arose around 1859, perhaps because the lawnmower was now mature technology. The original mower was developed in 1830 from a machine used to remove the nap from cloth, and it allowed smooth, true grass surfaces, something almost impossible to create with a scythe or with grazing animals, but organic mowers still had a presence. The Illustrated London News reported in the middle of 1859 that a lightning bolt had struck a sheep in London’s Hyde Park, summarily terminating its earlier sterling grass control services.

After about 1860, horse-drawn and then motorised mechanical mowers did most of the work.

Lawn tennis was developed in 1859 by
a solicitor, Major Thomas Henry Gem and his friend, a Spanish merchant. The two were living in Birmingham, England, and played a game that they termed “pelota”, based on a Spanish ball game, which they played on Perera’s croquet lawn. This later came to be known as tennis, and 15 years later the two formed the Leamington Tennis Club, which laid out the rules of the game.
Croquet even featured in Alice in Wonderland.

In 1868, the All England Croquet Club was created to provide an official body to control croquet and to unify the laws. The club’s members leased four acres at Wimbledon in 1869, and tennis courts were added later when the croquet fad waned.

The club changed its name to the All England Lawn Tennis and Croquet Club in 1899, and has held that name to the present day, even if the world just thinks of it as ‘Wimbledon’. Croquet had become a British craze in the 1850s, and the first recorded croquet game in the USA was at Nahant, Massachusetts in 1859.

Football was also emerging. In May, the rules for “Australian Rules” football were developed, though the Football Association, the founding body for the world game (or ‘soccer’, if you must) only wrote out its rules in 1863, with Rugby codes developing about 1870.

1859 was the year in which Allan Robertson, the world’s first golf professional died, still hating the new-fangled ‘gutties’, the golf balls with gutta percha in their hearts. They made the game too easy, he thought.

Not all sports owe their birth to lawn mowers. Polo was started in India in 1859 by the Maharajah of Manipur, Sir Chandrakirti Singh (who called it by a name which literally meant “horse hockey”).

It was the year lacrosse was named as Canada’s national sport and the first ice hockey game appears to have been played in Halifax in 1859 (ice hockey became Canada’s national winter game in 1994).

The first modern Olympic Games were staged in Athens, not in 1896 but in 1859! A Hellenic grain merchant named Evangelos Zappas convinced the Bavarian-born King Otto I of Greece to patronize an Olympic festival at Athens.

Otto was driven out of Greece in 1862, which caused the second Olympiad to be somewhat delayed, and these days, we take the second attempt of 1896 as the first of the modern series.

A Meyerbeer opera, Le Prophète, opened in 1849. It featured apparent ice-skaters (roller skaters), but that and an 1849 ‘spin-off’ ballet, Plaisirs de l’Hiver ou Les Patineurs helped to make roller skates popular, while Les Patineurs remains in the orchestral repertoire today.

In 1859, the Woodward skate with vulcanised rubber wheels, was unveiled in London, but people did more than demonstrate their own strength and agility. They went to see the experts in action.

Saturday, 12 September 2020

Hidden fashions in 1859

This is one of a series of entries are drawn from chapter 7 of my book, Mr Darwin's Incredible Shrinking World, and they all deal with life in that era. For background on the book, see the first entry in the series, Life in 1859, but if you just want to see the others, use the tag 1859, which appears at the end of each entry.

The problem with writing social/domestic history is that all too often, people at the time did not record the details of their everyday activities. We cannot always get the details we need to understand everyday life, even two life-spans in the past. William Perkin’s mauve, discovered in 1856, was new and different enough to draw attention, so we know it came into production in a major way in 1859, giving ladies a new (and safe) fashionable colour, even if it was derived from the noxious remnants of coal gas and coal oil production.

Sometimes an industrious journalist filled in the background while earning his fee, as when Septimus Priesse wrote about making and colouring bonnets. He described mordanting straw bonnets with an ounce of iron sulfate in two gallons of water, boiling them for an hour, then hanging them out to dry, adding that chip or leghorn straw needed less mordanting. Next, the bonnets were boiled in 2 gallons of clean water for an hour with half a pound of broken nutgalls and half a pound of logwood, two common dye sources of the time.

Then, he said, leave two ounces of best glue in two quarts of water overnight before boiling to dissolve it and straining the glue, now referred to as size. The next step was to soak the bonnets in the size, one at a time, before removing them, sponging off the excess size and drying before carefully shaping the hat, or placing it on a block to dry. The result will be a nice black bonnet. A few details might be deemed too intimate, but more often, they seemed too ordinary, so we sometimes have to rely on inference, or unpublished sources.

Diaries and letters are useful. Because Eliza Edwards’ letters described life in Hawaii to her family in New York, she included ordinary matters like donning rubber boots to walk through knee-deep rushing water. In her diary, Caroline Cowles Richards, a young girl in upstate New York, revealed how a friend pierced her ears for her so she could wear ear-rings — as well as revealing the fashion influences she experienced:

Mary Wheeler came over and pierced my ears to-day, so I can wear my new earrings that Uncle Edward sent me. She pinched my ear until it was numb and then pulled a needle through, threaded with silk. Anna would not stay in the room. She wants her’s done but does not dare. . . . It is nice, though, to dress in style and look like other people. I have a Garibaldi waist and a Zouave jacket and a balmoral skirt.

Not everybody agreed with fashion. Empress Eugénie of France had pioneered the crinoline, but she declared in 1859 that she was giving it up. Unmoved by the edict of a mere empress, the style held on. It was claimed in the press that in Istanbul, the Ottoman sultan had, by decree, imposed a limit upon the luxury of the Turkish women of high position, and ordered certain changes in their costume.

This does not ring true: perhaps it was put about by somebody annoyed by the challenge of trying to pass crinolined ladies on a narrow street, or to fit them into a pew, a doorway, an omnibus, or a carriage.

On the other hand, the crinoline was good for business. It had sparked 100 patents in France in four years: 4 in 1855, 16 in 1856, 30 in 1857, 37 in 1858, and 13 by July 1859. Covered steel crinoline (wire) sold at 50 cents a pound, and about three quarters of a pound was needed for one hooped skirt. The estimated usage in 1859 was 5 million pounds. At the end of the November, Scientific American reported that in Derby, 950,000 hoop skirts had been made since April 1, using 9,100,000 yards of tape and 445 tons of steel.

A Mr Wappenstein in Manchester received a patent in 1859 for making artificial whalebone from animal horn. This would be cut in long helical strips which were then flattened and heated before being coloured. They were suitable for use in both umbrellas and crinolines.

According to cricket lore, round-arm bowling was developed by a cricket player’s sister, who found that her crinoline got in the way of conventional underarm bowling. She is usually named as Christine or Christina Willes, but she is alleged to have come up with her innovation in the early 1800s, half a century before the crinoline. Her dress may not have been embroidered, but it appears that the story was.

An advertisement in the Victorian Cricketer’s Guide of 1859-60 offers batting gloves, wicket-keeping gloves, and “leg guards” but no protective boxes for the male players. There was no real call for them at the time, as the umpire would call ‘no ball’ if any bowler raised his arm above his shoulder.

Saturday, 5 September 2020

Life in 1859

In 2007, I realised that the sesquicentenary of the publication of Charles Darwin's The Origin of Species was coming. As an active historian of things scientific, I decided to write my own account, and casting around for themes, I read Richard Dawkins' comment to the effect that "the world changed after Darwin published", the suggestion being that the book caused change, when my view was that Darwin's book was but a symptom of a fast-changing world.

1859 was the year that Charles Darwin and Abraham Lincoln turned 50 (they were born on the same day in 1809) and by the end of the year, their names were becoming known, all over the civilised world. It was the year of the first oil well, the invention of the slide rule and spectroscopy (rapidly giving us enough extra chemical elements to make the Periodic Table mean something). It was also the year in which Mendel started investigating the genetics of peas, the Suez canal was started, key evidence for the germ theory of disease was being assembled, and tobacco-smoking was first identified as a cause of cancer—and that's just for starters!

Railways, telegraphs under the sea, steamships and internal combustion were all tying the world together in amazing ways.

The end result was a work entitled Mr Darwin's Incredible Shrinking World, which saw the light of day in 2008 as a print book which you may or may not be able to pick up somewhere: here's a quick outline.

The work is certainly available from Amazon as a Kindle e-book, and also from Booktopia, or you can listen to me talking about it here.

Anyhow, my next few entries are drawn from chapter 7 of that book, and they serve to describe life in that era. If you want to see the others, use the tag 1859, which appears at the end of each entry. I will begin with fashions.

Fashions, after all, are only induced epidemics.
George Bernard Shaw, Doctor’s Dilemma, preface.

British men in the 19th century were generally clean-shaven until soldiers returned from the Crimea with beards, though “literary men” had beards sooner. The young Charles Darwin had no beard, old Charles Darwin was bearded. In early 1861, Abraham Lincoln explained just before his inauguration why he would be the first US President to have a beard in office: an 11-year-old girl, Grace Bedell, wrote and suggested he should grow one because his face was thin, but if fashion did not sway Lincoln, it must surely have influenced Grace Bedell.

Men used lead-based dyes on grey beards or hair and many bright colours contained a variety of heavy metals. Women who dyed their hair were at risk, but they had more to fear from arsenical dyes in their gowns, while everybody was threatened by green wallpaper, dyed with arsenic compounds — but it was fashion. Fashion was just as lethal to the whales which supplied whalebone for corsets and crinolines, and it had been as bad for the beavers which had provided the fur needed to make gentlemen’s hats until the 1850s.

Then the varnished silk hat took over, but Scientific American did not like them, saying the hard-shell hats were a menace. Some of these had gauze tops for ventilation, but most did not. While felt hats are somewhat porous and so somewhat ventilated, silk plush hats were saturated with lac-varnish and completely airless. They needed perforations at or near the band, argued the reporter. Later in the year, William Warburton obtained a patent for a machine that used heated points to perforate the sides of a hat, a system that Scientific American recommended for any headwear coated with varnish.

Ladies’ underwear was causing some worry. With the development of the crinoline, where hoops of whalebone, wire or other stiffening converted the dress into a giant bell, exposure of the limbs was more likely. Legend has it that ladies, fearful of being blown on their sides by wind or swooning, suddenly wanted more modest underwear, but the evidence is, at best, scanty — unlike the new underwear, it seems.

And in Britain, the poor were still being banged up in workhouses. I may or may not get back to discuss the fate of Thomas Drewery's orphans in Victoria, not long after that, but I have already described the fate of Australian poet, Jennings Carmichael, who died in an English poorhouse.

What is a good scientist?

Before I take one last look at the scientific method, what makes somebody a scientist? In the world of advertising, anybody pushing a treatment or cure and wearing a white coat is seen as a scientist, and most people who say they can refute Darwin, Einstein or “Big Pharma” will also claim to be a scientist — as will a goodly proportion of climate deniers.
Is it all about equipment? This is
Tycho Brahe's Uraniborg.

The term has been used since 1840 to describe people who study scientific subjects: “We need very much a name to describe a cultivator of science in general. I should incline to call him a scientist”, said William Whewell (1794 – 1866), writing in 1840. Before this date, scientists were usually referred to as natural philosophers.

In general, we expect that scientists will work in accordance with the scientific method, and that they will report their findings in such a way as to allow others to repeat the experiments they describe. There are also expectations that the work of a scientist will not be based on fraud, faith or pious hopes, and that the work will be properly notified in the “scientific literature”, that is, by a “paper”, a report published in a peer-reviewed journal devoted to such reports.

Most people see an advantage in calling their subject “a science”, while the “real scientists” prefer to keep science pure, so that “social sciences”, “political science”, and especially “creation science” are rejected by mainstream scientists, on the ground that these other “scientists” do not have a clear body of theory and laws which can be used to generate new experiments and studies.

That said, we can’t ignore the scientists, because they are strange beasts. Gilbert White, vicar of Selborne and Jane Austen’s near neighbour, had a gentleman amateur’s fascination with weather records. So did John Dalton, schoolmaster and amateur chemist, who gave us the modern notion of the atom in 1808. Dalton kept a weather diary for 57 years until he died in 1844.
Dolly Pentreath memorial, Mousehole, Cornwall.

White also corresponded with people like lawyer Daines Barrington who, among other things, examined the young Wolfgang Amadeus Mozart to see if the boy was a clever hoax, managed by boy’s father. Barrington suggested in a report to the Royal Society that the lad was not only genuine, but likely to be greater than Händel. Barrington also interviewed the last speaker of Cornish, Dolly Pentreath, and had some original ideas about fossils and polar exploration. White wrote to him about the keys in which owls hooted at Selborne.

Gilbert White died in 1793, Daines Barrington in 1800, at a time when the men of science were still expected to commit themselves to a range of endeavour and enquiry. By the late 1850s, that era was over and the up-and-coming scientists had begun to specialise.

The names of those planning to attend the Leeds meeting of the British Association in 1858 were listed in The Times, ahead of the meeting. The list reads “Sir David Brewster, Professor Faraday, Sir Roderick Murchison, Dr Whewell, Professor Wheatstone, Professor Airy, Sir William Hamilton, Sir Benjamin Brodie, Robert Stephenson, M. P., General Chesney, Mr. Hopkins, Mr. Darwin …”.

Darwin’s name is followed by 33 others, few of them known today, even to those familiar with the period. Darwin was top-drawer, but not one of the truly great names like Astronomer Royal George Airy or William Whewell, the man who coined the word ‘scientist’.

Brodie (a surgeon who opposed amputating diseased joints), Chesney (Francis Rawdon Chesney, who surveyed a Suez Canal route in 1829) and Hopkins (probably William Hopkins, a mathematician, geologist and Cambridge coach), people barely heard-of today, were all mentioned ahead of Darwin, but like him, many of them entered science through a back door. It was a field that any determined person could enter.

Michael Faraday was a bookbinder’s apprentice who read then books he was binding, carried out some experiments, attended some lectures, and then joined the world of experimental science. Wheatstone first came to attention as a maker of musical instruments (and the inventor of the concertina) but he went on from there.

Brewster trained as a clergyman, and in 1825 Darwin was a medical student at the University of Edinburgh but was so horrified by an operation performed on a child without anaesthetic that he gave up his studies without completing the course. Scientists were not trained as such before about 1850: they emerged, and got together and talked, like the members of the Birmingham Lunar Society.

I suppose you want to know about them, well you should have been paying attention: I did them three weeks back!

Sunday, 23 August 2020

Disaster theories

Did you know that I collect volcanoes?

I wrote this some years back, but it remains relevant.

One of the hallmarks of popular science is the disaster scenario, because it sells well. Sometime, though, the scenarios are popular, but not science. Let us consider the view that asteroid strikes cause volcanoes to erupt.

The world’s flood basalt provinces are the remnants of the largest eruptions of lava on Earth, with known volumes of individual lava flows exceeding 2000 cubic kilometres. By comparison, the ongoing eruption of Kilauea volcano on Hawaii has produced just 1.5 cubic kilometres in 16 years!

The very largest are the Deccan Traps and the Siberian Traps (‘trap’ in this case is a Sanskrit word meaning ‘step’, because of the way the flows weather and erode later to produce stepped hillsides). The Columbia River flows shown above are rather smaller.

A number of the flood basalts formed at times close to the occurrence of certain extinction events, in particular the Newark outpouring of a million cubic kilometres, some 201 million years ago; the Deccan outpouring of perhaps 2 million cubic kilometres, around 66 million years ago; and the Siberian outpouring, also of some 2 million cubic kilometres, around 249 million years ago.

The Deccan outpour lies close to the Cretaceous-Tertiary, at the time when the dinosaurs all died, and the Siberian event matches closely the Permian-Triassic boundary, while the Newark event matches the end of the Triassic.

The probability of having three major volcanic events that would each typically last about a million years should occur within 1 million years of major extinction events during the last 250 Myr (of which there are about 12) is about one in ten thousand.

This has tempted many in the past to assume that these volcanic outbursts were responsible for the extinction events, and when an asteroid in Mexico was associated with the Cretaceous-Tertiary extinctions, some vulcanologists argued that the impact of the asteroid must have triggered the basaltic flow.

How serious would such an event be? The only flood basalt eruption since written history began was the 1783-84 eruption of Laki in Iceland. This produced a basaltic lava flow of 565 cubic kilometres, which represents only 1% of the volume of a typical large igneous province (or LIP) flow, but the eruption’s environmental impact resulted in the deaths of 75% of Iceland’s livestock and 25% of its population from starvation. If such a relatively small eruption happened today, all air traffic over the North Atlantic would probably be halted for three to six months.

So it seems possible that an eruption bigger than that would be enough to possibly trigger an extinction event, but all the same, the idea that volcanoes can erupt when the Earth is smacked by a large comet or meteorite has become a popular idea in geology. That may be so, but it seems there is no proof to back the claim up.

Not only is there no firm evidence that an impact started a volcanic eruption on Earth or on any other planet, there is no known mechanism by which this can occur. According to Jay Melosh who had studied the matter closely:

This idea probably got its start in pre-Apollo days when early observers of the moon noted the common occurrence of dark material — usually supposed to be lava — filling the nearside impact basins. A logical inference is that this is a genetic association: the impacts caused lava to upwell in the biggest craters after they had formed, eventually filling them.

This view should have collapsed in 1965, when the Russian probe Zond 3 made good photos of the lunar farside that showed that the farside basins are not filled with basalt. Moreover, the samples returned from the moon by the Apollo missions showed that the mare basalts are considerably younger (up to about 1Gyr) than the basins in which they lie.

The main point Melosh makes is that there seems to be no way that the impact of an asteroid could punch a deep enough hole to let all that basalt out: “Even in the 100-km (transient) diameter Chicxulub crater, the Moho beneath it is barely disturbed, with less than a few km uplift beneath the centre. Under these circumstances pressure relief melting seems very unlikely, even in the largest known terrestrial craters.”

So exciting as the scenario may be to movie makers, it seems to be an idea without legs, and that isn’t all the bad news for those who enjoy a bit of doom and gloom.

Wednesday, 19 August 2020

The pendulum and the shape of the planet

The 'researchers' of the Internet, the climate clowns who cherry-pick data to prove their dopey obstructionist theories, commonly demonstrate how little they know of the ways that scientists can measure and discover things.

With the exception of the Flat-Earthers (and even climate clowns hate it when they are treated as latterday Flat-Earthers!), we all believe that the Earth is pretty much a sphere, but pretty much leaves wiggle room, and strange as it may seem, it was an upgraded version of a playground swing that revealed the precise shape of our globe, which some people likened to a watermelon stood on end, while others thought was more like a pumpkin.

This is the story of how they did it, almost three centuries ago.


In some parts here, the main measurements have been converted to their modern equivalents. The unconverted unit called the ‘line’ is 1/4 of a barleycorn, a twelfth of an inch, or about 2 millimetres.

The barleycorn measurement turns up in the oddest of places. Edward I, King of England, decreed in 1305 that “three grains of barley, dry and round, make an inch”, and if you change from a size 7 shoe to a size 8 shoe, the difference in length is one barleycorn.

Now to our story:

In 1672 Jean Richer reported that the period of a pendulum varied with latitude, and Isaac Newton said that Richer’s variation of pendulum was due to equatorial bulge, a comment offended the French. By this time, nobody thought the world was a perfect sphere any more, but France and England disagreed, and national honour was at stake.

Isaac Newton had proposed that the Earth was an oblate spheroid. If this were so, argued Newton, the precession of the equinoxes (we may or may not come to those later) could be explained. French scientists had taken some sloppy measurements, getting results which suggested that the Earth was more like a watermelon on its end than a pumpkin.

The French Académie set out to determine the truth of the matter by experiment, measuring a degree of latitude in Lapland and in Central America. Among those who went to Lapland was Pierre de Maupertuis, while the American group included Pierre Bouguer and Charles La Condamine.

Richer’s pendulum clock had been accurate in Paris but it lost two and a half minutes each day at Cayenne in Africa, closer to the equator. Clearly, more data were needed, and scientists were rushed to different places in 1735, mainly in South America, a mere 63 years after the comment. Newton had died in 1727, but the French still wanted to show him up, the insolent upstart!

We know Pierre Bouguer’s name today mainly in the form of Bouguer anomalies. This name commemorates his pioneering work in the Americas. When the acceleration due to gravity is measured very accurately, small local fluctuations can indicate equally local deposits of high or low density mineralisation — these fluctuations are the Bouguer anomalies.

Bouguer spent much of his life studying gravitational effects. In 1740, he estimated the value of G, the universal gravitational constant, using a mountain as an attracting mass. A method such as this can only be as accurate as the information the enquirer has about the interior of the mountain, and there were other problems which Bouguer could not have known about. We will ignore those for now, but the key word is isostasy, if you want to know more.

The French work in Central and South America between 1735 and 1743 was to measure the length of an arc of one degree of latitude at the Equator. Other scientists went to Lapland to measure a close-to-polar degree. Any difference in the lengths would reveal whether France or Britain had the right shape.
Inserted without comment.

Here, from the French Académie des Sciences Memoirs, is part of a letter from Bouguer to René de Réaumur in 1735, followed by part of Bouguer’s 1749 report of his findings.

I have made here [in San Domingo] a simple pendulum of steel which I have made as invariant as possible. It has a bob of [12 kilograms], about [12 centimetres] in diameter and [3 centimetres] deep. To keep it swinging true, I have put on the rod a crossbar of iron to serve as an axis, at right-angles to the rod. The instrument is mounted on a tempered steel knife-edge on two steel springs. These two springs are mounted on a copper plate in which there is a hole for the rod. The plate rests on a stool [1.5 metres] high, and is levelled by three screws…

We used the barometer that we set up to study the balance between the weight of the mercury and the air in all the accessible parts of the atmosphere. We saw how many feet we had to rise or descend to make the mercury change height by one line. It is then necessary to find the specific weight of air that balances other bodies. In this way, I have found by comparison with copper that on the top of Pichincha, there is a loss from unity of 1/11 000. Now it follows that the weight of my simple pendulum also loses 1/11 000 part of its weight. This loss produces a similar reduction in the restoring force, and naturally, I found the pendulum to be slow by 1/11 000. To correct this loss, it was necessary to adjust the pendulum’s length by 4/100 of a line…

Translation of the translation: Bouguer had an accurate pendulum, mounted on a wooden stand (the stool) and it was adjustable. He used a barometer as a way of measuring altitude. By timing the pendulum, he could get a measure of g at different heights above sea level.

The degree-measuring expeditions succeeded in proving Newton correct, but one of the more lasting effects came from La Condamine’s explorations while he was there, travelling over a large part of South America, and then 5000 km down the Amazon.

When he returned to Europe, La Condamine brought with him what the locals called cauchu, and the French still call caoutchouc. Thanks to Joseph Priestley, we still call it ‘rubber’, because it can be used to rub out pencil marks, and what is an eraser in some English-speaking countries is still called a rubber in others.

Friday, 14 August 2020

Benham's colourful tops.

 Charles E. Benham (1860-1929) was a journalist and inventor, and he deserves more than this, or what his Wikipedia entry, offers. I was triggered to go here this morning because of a comment Stew made about my last entry: there may be more, later.

When I first discovered the Benham disc, I was delighted, because I am colour-blind. The Benham disc is a black and white patterned circle, which looks coloured when it is spun around. I had heard of these things but I had never tried them, and I thought it would be interesting to see whether they had the same effect on a colour-blind viewer. Being colour-blind does not mean that you “see everything in black and white”, as David Brewster said. It simply means you see colours differently. It occurred to me to wonder if maybe I would see different colours in the disc from those other people see.

Benham described his illusion in an article published in Nature  back in 1894. In those days, if you wanted to see the disc, you would look for the design on a children’s top, known, predictably, as ‘Benham’s top’. The first account was a brief and anonymous one, noting that the ‘disc’ on the top was a black semi-circle, with the white half of the circle divided in four, and with black arcs painted in.

As the disc is rotated, people see different colours from the different black arcs. And, as the reporter noted, if “. . the direction of rotation is reversed, the order of these tints is also reversed. The cause of these appearances does not appear to have been exactly worked out.”

An ‘Artificial Spectrum Top’, devised by Mr. C. E. Benham, and sold by Messrs Newton and Co., furnishes an interesting phenomenon to students of physiological optics. The top consist of a disc, one half of which is black, while the other half has twelve concentric circles drawn upon it. Each arc subtends an angle of forty-five degrees. In the first quadrant there are three such concentric arcs, in the next three more, and so on; the only difference being that the arcs are parts of circles of which the radii increase in arithmetic progression. Each quadrant thus contains a group of arcs differing in length from those of the other quadrants. The curious point is that when this disc is revolved, the impression of different colours is produced upon the retina.

(Nature , 51 (1309), November 29, 1894, 113–114.)

There followed an animated correspondence, during which Benham stepped in. Illuminate the top with a bright sodium flame, he said, and you will see a very clear blue, and a very clear red. And now the controversy heats up: immediately underneath, in the same issue, Professor Liveing retorts that he has seen no such colours: the phenomenon is obviously a subjective one. Clearly there is room for more research here.

It is unclear whether Nature  thought so too, for they go on in the same column to publish next a letter from F. G. Donnan in Leipzig, suggesting that we need a new word in chemistry: ‘solute’, and the discussion seems to have died there. Well, as far as I can judge, I see the same colour effects as other people, which means we won’t learn anything about colour blindness from the Benham disc. But how about trying to learn about colour vision? What causes the colour effect as the disc slows down?

Most explanations seem to speculate rather than to explain, but here is the official version as found in psychology text-books. We have three kinds of light receptor in our eyes, in the same way there are three kinds of phosphor in a colour TV. Speaking crudely, these receptors, the cone cells, are all sensitive to just one of red, green and blue.

According to the theory, you need all three kinds of cone in the retina of your eye to see colours normally. Somehow, the cones which pick up one of the colours (red, for example) must react differently to flashing lights of a particular frequency. So with different size black bits on the disc, we get different frequency effects, and so our eyes are stimulated to ‘see’ different colours.

Well, that’s what the theory says. Some time in the future, a careful and critical look at it, will reveal once and for all whether and how this official explanation operates, and where it breaks down. There is probably a Nobel Prize in this for somebody, though they will need to acknowledge Gustav Fechner, and that's a hint.

Thursday, 13 August 2020

The Birmingham Lunar Society

Once upon a time, they say, there was a wonderful Golden Age of scientific communication, an age when the most prominent scientists and admiring lay-people were in frequent contact, either with each other, or with each others’ works. To exist at all this age probably had to await the development of the railway, the telegraph, and machine type-setting.

I suspect this Golden Age came at the absolute height of public scientific interest and endeavour, a time when scientific creativity was pouring out all over the place, and discoveries sparked off other discoveries, almost at the speed of light. All that was required was the transmission of the original idea.

Calculating what destroyed the Golden Age is harder: it might be sufficient to blame television, but the era probably died earlier than that. Maybe there never was any Golden Age of science communication at all. One thing is certain, though: there was a definite Dark Ages for scientific communication, and they died out around 1800, when scientific journals were first published, including the journal which nearly robbed Alessandro Volta of his rightful credit.

If you were a scientist in provincial England in the late 1700s, or worse yet, in colonial Australia, tidings of new discoveries were an unconscionably long time coming, and much of the news came only in the form of private mail. This helps to explain why so many scientists banded together to share their news, but what I find harder to explain is why a few of these groups were so hugely successful. Groups like the Lunar Society of Birmingham, for example.

The ‘Lunatics’ got their name from their solution to the risks of travelling the dangerously rutted roads around Birmingham to get to their meetings. It was unsafe to travel those roads in the dark of a moonless night, so they would meet on the night of the full moon. The real problem with Birmingham was that it might have been a good place for building a factory, but it was the most dreadful starting place for a trip to London.

It wasn’t much better for getting to Edinburgh from either, the city where so many of the members had learned their science. They might as well have been in the colonies! For any sort of intellectual stimulation, they and their friends had to rely on what came to hand in their home town, or near to it.

They were a tightly interlinked and brilliant little group, and the Royal Society in London had nothing on them. The Royal Society’s members were a bunch of dullards and dilettantes by comparison. Upper Class twits, Tories, that sort of thing, nothing like the Birmingham mob at all.

And that brings us to one of the problems with the Birmingham Lunatics: they were seen as a mob of radicals, people who felt American and French Revolutions were Good Things and said so, which wasn’t a good idea, for the spirit of a former-day Senator McCarthy was alive and well in eighteenth century England.

At one point, the mob even burned down Priestley’s house to show what they thought of him. If ‘Congreves’ (the matches, that is, named because, like the incendiary rockets of Sir William Congreve, they set fire to things) had been invented back then, they might have got Joseph Priestley as well, but they had to send off for ‘some fire’, and Priestley made his escape. Recall, though, that while the members called themselves ‘Lunatics’, it was a real lunatic, Farmer George, King of England, who tried to get the Royal Society to reverse its stand on lightning rods, simply to contradict the American rebel, Benjamin Franklin.

You will find this story elsewhere. To its credit, the Royal Society refused the King’s demand, but Farmer George would never have tried the same stunt on the Lunar Society of Birmingham. After all, one of their corresponding members was that same villainous Ben Franklin, and one of the Society’s sources of inspiration (some call him a founder), William Small, had been the teacher of Thomas Jefferson in America, and had now come to Britain.

The other founders included a country doctor, Erasmus Darwin, who is fairly well-known as grandfather to Charles Darwin, but Erasmus was quite an intellectual giant in his own right. As we have seen, long before Charles got into the evolution business, Erasmus had proposed a Lamarckian sort of evolution, beating Jean-Baptiste de Lamarck to the idea by a number of years.

Charles’ other grandfather, Josiah Wedgwood was a member as well. So was William Withering, who discovered that the foxglove plant contained a steroid substance which we call digitalis, and use for heart disease.

It didn’t take long for other members to come rolling up, and the effectiveness of such a society soon became obvious. This was a time of breakthroughs and new ideas, a time for rapid development. It was also a time of simple apparatus to measure the extents of simple principles, so almost any participant could experiment further.

As I mentioned, they were mostly trained at that cradle of scientific education, the University of Edinburgh, and many of them were involved in manufacturing, so new problems arose quite frequently, nice knotty problems for the others to tackle.

But what would it take to establish a similar Golden Age of science and science communication and application today? Was there a magical formula, or was it just good fortune that so many people came together and sparked off each other? Was it because they were elitist, or only attracted an elite? As newsgroups, fora and email lists develop and mature on the Internet, will they begin to fill that role?

Only time can tell — but I think the email list is already dying away.

Water wheels

Left, an overshot waterwheel in Poland, right, an undershot waterwheel, Den Gamle By, Denmark.
The water wheel was the start of a whole, and rather serious set of simple machines, devices that used power. The water wheel gave more power more cheaply (once a mill was built), it helped feed a lot of people, but more importantly, it set people to thinking about the mechanical works of a mill.

Water mills probably started in Greece, some time before 80 BCE, because that was when a Greek poet called Antipater of Thessalonika mentioned young women being relieved of the work of operating a hand-mill, now water had taken over the hard work.
Soon, waterwheels began to spread into other areas where there was plenty of rainfall, all year round, places where slaves were hard to get. It was the first labour-saving device. The water wheel may have got its start, though, as a device used to raise water from a river to fields, high above the river bank, and that requires some explanation.

Today, if a moored paddle steamer sits in a current and the paddle wheel is disconnected from the engine, the wheel will turn. Something similar would happen to a water-raising wheel (usually powered by humans, working it as a treadmeill) when it sits in the current of the river. This is the simplest of water wheels, the undershot wheel, where water passes under the wheel, making it turn.

Then there is the more efficient overshot wheel where water drops onto the front side of the wheel and carries the front of the wheel down. Both the undershot and overshot wheel need at least two gear wheels to transfer the rotation through 90°.

Waterwheels were not as good at gathering energy as the efficient turbines in modern hydroelectric stations. Still, when there were no animals to feed, all you had to do was have a big enough mill, and enough fall to get enough energy from it.

This was a special problem with overshot wheels, where mill owners needed to take water out of the river, somewhere upstream, and run it through a channel that wound around the contours on a gentler gradient than the river bed.

Sometimes this would be helped out by a weir or a dam that raised the water level, but if there were several mills along a river, they would sooner or later start to interfere with each other. The Domesday Book was completed in England in 1086. This inventory of what the Normans had taken when they invaded England listed 5624 waterwheels in England, about one for every 50 households.
Bread was a staple food, and so mills were needed, all over the country. The Domesday book also records two mills in Somerset which paid their rent, before 1086, with blooms of iron, which makes it fairly clear that those mills were being used to forge iron. 

Cistercian abbeys in 12th century France commonly used waterwheel power to grind grain, to sieve flour, to full cloth and to tan leather.

At other times, water power crushed olives and operated bellows for forges and the fires used to brew beer. A paper mill powered by water existed in Spain in 1238, and seven such mills were to be found in Italy by 1268. Paper was made by pounding linen, either by hand, or by foot, or by water power. Guess which one was more popular with the workers?

Water power was easier. when you could get it. In France, a tributary of the Seine River, the Robec, had two mills in the 10th century, four in the 11th, ten in the 13th and twelve at the start of the 14th century. Before long, the medieval world was running out of space for mills, and disputes began to break out as dams and weirs grew higher, backing water up to the next dam upstream, reducing the fall at the upper dam.

At peak times, the Garonne River at Toulouse in France has a flow of up to 9000 tons of water a second, about a fifth of a cubic mile or 780 megalitres of water a day. Damming something like that meant driving thousands of 6-metre oak logs into the river bed in two rows and then filling the gap between with rocks, gravel, oil and wood to make a water-tight wall.

There were three Garonne dams: Château-Narbonnais, La Daurade and Le Bazacle, and between 1278 and 1408, various acts of dam-raising led to lawsuits and orders to demolish dam extensions and pay damages that were mostly ignored. By 1408, the La Daurade company had ceased to exist, its last shares snapped up by the shareholders of Le Bazacle, ending the dispute.

In later times, windmills took over part of the task, simply because they could be located where there was no reliable flow of water, but windmills were not as powerful. The early Industrial Revolution grew up near rivers, but with time, the waterwheels were replaced by steam engines. The world was ready for them, because the mechanical skills needed to build and fix mills driven by water and wind were very much the skills needed to make early steam engines.

Friday, 31 July 2020


In logic, a paradox is a contradictory or implausible conclusion which seems to follow by valid argument from true premises. Aside from Zeno’s paradox, and Maxwell’s demon, proposed by James Clerk Maxwell, Erwin Schrödinger’s cat and Olber’s paradox, all dealt with in other places, the most interesting paradoxes are all logical challenges.

The paradox of the Spanish barber concerns a barber who is asked how business is doing. “Not badly,” says the barber. “I shave everybody in the village who does not shave himself.” The problem: who shaves the barber?
Logicians with a smattering of Greek will
share my delight in this Athenian street sign.

Epimenides of Crete is credited with one of the simplest paradoxes: “All Cretans are liars”, meaning by implication that this statement (made by a Cretan) was necessarily untrue. But if it is untrue, then not all statements made by Cretans are liars, and so on.

There is a more complex form of this paradox, consisting of two sentences. “The next sentence is false” and “The previous sentence is true”. Or "there are two erors in this sentence".

The dilemma of the crocodile: a crocodile seizes a child, but promises to let the child go, if the father guesses correctly whether he will do so or not. If the father offers as his guess the opinion that the crocodile will not return the child, what should an honest crocodile do?

A lawyer is trained by a teacher who says “you must pay me for your tuition after you win your first case”. Several years go by, during which time the teacher gets annoyed because the lawyer has yet to win a case, and sues the lawyer, saying “If I win my case, you must pay me, but if I lose, you have won your first case and must pay me.”

“Not so fast”, says the young lawyer. “If I lose the case, I have yet to win a case and need not pay you. But if I win, then by the court’s judgement, I do not have to pay you.” Does the lawyer have to pay?

Some words describe themselves, so “short” is a short word, but “long” is not a long word, “English” is an English word, but “German” is not a German word, and so on. We call words which describe themselves as autological, while words which do not describe themselves are called heterological.

But what about the word “heterological” — does it describe itself or not? If “heterological” is heterological, then it describes itself, and so it is autological. But if the word is autological, then that means it is a word that does not describe itself … or something.

Paradoxes can be useful ways of extending our knowledge, or at least ways of finding the right questions to ask. Fermi’s conjecture, also known as Fermi’s paradox, was offered by Enrico Fermi. In simple terms, it asks why, if the Galaxy is filled with intelligent and technological civilizations, haven’t they come to us yet?

There are several possible answers to this question (good taste on the ETs’ part, distance, or a recognition that contact with a superior civilisation is damaging to the more primitive one), but as we only have the vaguest idea what the right conditions for life and intelligence in our Galaxy, this paradox probably has no ready answer.

Paradoxes are also useful as a form of the mathematical proof called reductio ad absurdum, an argument which comes to an absurd or contradictory conclusion, hence showing that an initial assumption must be wrong. This shows up well in the so-called grandfather paradox of relativity. Imagine that your grandfather has just built a time machine, which you then use to go back in time, to give your grandfather the plans, so he can later build the time machine.

You reach him at a time where he has yet to meet your grandmother, he refuses to believe you, and in an argument, he steps out into a road, and is run over and killed by a passing car. He has now died before he met your grandmother, so you do not exist, since one of your parents does not exist, and the time machine does not exist, so you cannot be there in any case.

This is one of the arguments physicists use to support their belief in the causality principle. Others say the fact that we have never met time travellers proves that there will never be any, but this is probably one of the most useless of paradox types.

Let's get back to more practical stuff!

Tuesday, 28 July 2020

Zeno's paradox

Zeno of Elea was a philosopher with a wicked imagination, and he made up a puzzle which can be simply described like this. Suppose you have a hundred-metre race between a man called Achilles and a tortoise. Assume that Achilles runs ten times as fast as the tortoise, and that he gives the tortoise a ten-metre ‘start’.

Zeno said that Achilles can never catch the tortoise for while the man runs the first hundred metres, the tortoise waddles ten metres, and is still ahead. The man runs the extra ten metres, but the tortoise gains an extra metre.

As the man sprints desperately across that metre, the tortoise sneaks a further tenth of a metre, and while Achilles is lunging across that tenth of a metre, the tortoise drifts another centimetre, and so the human can never catch the tortoise. The same argument can be used to show that a thrown spear can never reach its target!

Zeno’s aim was to prove that something we can see happening is impossible, from which it follows that since we can see the impossible happening, our senses must be faulty. In other words, his paradoxes were designed to make people think. Later, Aristotle would argue against Zeno’s ideas, and Zeno’s assumption that space and time were infinitely divisible would make Democritus try to resolve the problem by suggesting that matter was not infinitely divisible, finally coming up with the idea of atoms—and all because Zeno believed the senses could not be trusted —because even though Zeno had proved that Achilles could never catch the tortoise, we know that in real life, he can!

Other paradoxes can be more fun...

That is to say: to be continued

Monday, 20 July 2020

Finding iodine

There are thirty recognized isotopes of iodine, but only one of these, iodine–127, is counted among the stable isotopes, and is found in nature. Radioactive iodine-125 is routinely used in tracing problems with the thyroid gland, and another isotope, iodine-131 has been commonly used to treat overactive thyroid conditions. The “iodine” which is commonly used on small wounds is tincture of iodine, a solution of potassium iodide and iodine in ethanol.

Iodine is element number 53 in the periodic table, atomic weight 126.90. This element was first isolated in 1811 by Bernard Courtois (1777 - 1838). 

Like the Germans in the First World war, the French found themselves restricted by a British naval blockade which stopped them accessing American sources of potash during the Napoleonic wars.  The potassium carbonate was used to make potassium nitrate for French gunpowder, but the seaweed also contained a variety of other chemicals, one of which was an iodide.

In treating seaweed ash with acid to get rid of sulfur compounds, Courtois noticed a purple vapour, which condensed to make crystals of iodine. He later passed this information on to Sir Humphry Davy, who proposed the name “iodine”, from the Greek word for the colour violet, iodes. The credit for suggesting the name is sometimes given to Joseph Gay-Lussac, but this is incorrect.

As mentioned above, iodine is needed in the production of thyroxin, and a deficiency in dietary iodine leads to goitre, so that foods (especially table salt and bread) in many parts of the world now have traces of iodine added, although this is unnecessary in areas where seafood is available.

Part of the hormone ‘picture’ was already there in 1905, because a number of diseases were linked to disorders in particular glands: goiter and cretinism were associated with an enlarged thyroid gland, but this was rightly regarded as a deficiency disease caused by a lack of iodine. Many folk remedies used iodised salts or sea foods rich in iodine, even before we knew iodine existed (the element was detected in 1813). Its role in preventing goitre became more obvious after Eugen Baumann (1849–1896) showed in 1896 that iodine was only concentrated in the thyroid gland.

Curiously, Courtois also discovered that major fascination for undergraduates of a certain kind, nitrogen triiodide, which forms tremendously unstable crystals that will even explode when hot water falls on them.

I have no intention of revealing how I discovered this fact, as I conclude now that I had a lucky escape: Pierre Dulong  lost three fingers and an eye investigating this substance — which may explain why, when he was formulating what is now called “Dulong and Petit’s Law”, he chickened out, and did not investigate tellurium, fraudulently manufacturing the data for that and several other elements.

The reason is probably that when you handle tellurium, it is absorbed, and you get “tellurium breath “. Not to mince words, you stink of stale garlic for months after working with tellurium compounds. Dulong  either feared that, or perhaps he was attached to his remaining fingers and wished to stay that way.

Everything (other than Dulong's fingers, perhaps) is connected.

Sunday, 19 July 2020

The art of estimation

Like the previous entry, this comes from my (now) out-of-print volume, The Speed of Nearly Everything.  I may get around to releasing it as an e-book, if enough people think it's a good idea.

To a physicist, the notion of an immortal rabbit is quite acceptable. As a boy, my English teacher encouraged me to psychoanalyse Macbeth, even though I objected that we shouldn’t, since Freud hadn’t been invented when Shakespeare was writing. Ever a historically-minded cuss, I argued that it would be more relevant to look at the political situation in London, with a Scot sitting on the throne. Exasperated, he exhorted the class to engage in the willing suspension of disbelief.

And well he might, if he wanted us to accept some of the artifices and conceits of coincidence found in the 19th century novel, but we scientific types were subjected to much hardier fictional nonsense than that.

We routinely solved problems that involve a steel girder of negligible mass, suspended at its centre of gravity by a silken thread, and before we were too far advanced, we heard our first physics joke. It was about the three scientists who were trying to pick the winner of Australia’s premier horse race, the Melbourne Cup, which is held each November.

The mathematician gathers a wealth of data on weather, rainfall, wind, pollen counts and other possible influences, and three years in a row, fails dismally to pick a winner. At the end of those three years, the geneticist has just finished drafting a plan for a breeding program that should, in five generations, produce a winner, but the physicist has got it right, three times in a row.

The others ask him how he did it. He reaches into his pocket and produces an envelope which he turns over. Then he draws a circle on it. “Consider,” he says, “a spherical horse running in a vacuum…”

In fact a spherical cow or spherical horse can be a useful starting point to explore ideas, to get a first approximation that can be extended. Take the yarn about the bumblebee that was shown not to be able to fly: this is usually trotted out as evidence that scientists are thick, but there is a little more to it than that. In 1934, a French entomologist called Antoine Magnan tried to apply an engineer’s equation to bumblebees, and showed that according to that equation, designed for aircraft that did not flap its wings, the bee could not generate enough lift.

A bumblebee, coming in to land (or fall?)
There is a great deal of folklore wrapped around this “event” and who actually was involved, but it appears that the equation was worked out by André Saint-Lagué, and while the incident is often dressed up as “a scientist proving that bumblebees can’t fly”, all that was really shown was that the equation was inadequate to describe the flight of the bumblebee.

Magnan had shown that you can’t apply that particular equation to bumblebees, rather than proving that spherical bumblebees can’t fly, even if real ones, flapping their wings at 130 times a second, move happily along at 3 metres/sec, 11 km/hr or 7 mph. Like Zeno’s paradox (which will be in the next blog entry), Magnan’s calculation merely showed that there was a faulty assumption in there somewhere. The mathematical model was flawed.

When we escaped from the English classroom to the lab, we learned of marvels that could be done with simple apparatus. The muzzle velocity of a bullet could be measured with nothing more than a block of wood, a piece of string, a protractor and a measuring tape.

Our physics teacher, equally as at home with fiction as our English teacher, explained how, in the days of gunpowder and muzzle-loading firearms, slight variations in the ingredients, their amounts and proportions, could make a lot of difference. The most obvious measure was the speed at which a cannon ball or musket ball left the barrel of the gun, or in physics-speak, the muzzle velocity.

The idea was quite simple. You suspend a large block of wood and fire a bullet at it from close range. The bullet lodges in the block, and the energy of the bullet is transferred to the block, which swings like a pendulum. Then one simply has to measure the swing angle and calculate the height the block reaches.

This device even has a name: it is called the ballistic pendulum, and it has been around since the 1742, when it was invented by Benjamin Robins. From the swing, or so we were told, it is a fairly elementary calculation to estimate the energy and hence the velocity of the bullet. Unfortunately, this explanation ignores the 800-pound spherical horse which is rolling around the room.

Some of the energy goes into deforming the bullet and the wood, some is wasted as friction, and to do any calculations, we have to assume that the bullet stops instantaneously (which is as likely as a girder with negligible mass). Of course, if you are trying simply to compare different grades of gunpowder, rather than measuring the muzzle velocities, the losses will be similar in each case, and can be ignored. Whichever powder produces the biggest swing is the best, if everything else is kept constant — and in fairy physics, that always applies.

Robins was born to Quaker parents, but as a mathematician, he tried to make gunnery a science. Along the way, his ballistic pendulum probably showed that Indian saltpetre made the best gunpowder. He died in India in 1751, supervising the construction of forts, and a few years later, the British drove the French out of India, which let them have all that excellent saltpetre for their own use.

Curiously, the pursuit of novel sources for saltpetre during the Napoleonic wars led a French chemist, Bernard Courtois, to discover iodine, but that's another story...the next story, in fact.

Friday, 17 July 2020

That speedy botfly

I revived this excerpt from my out-of-print book The Speed of Nearly Everything when the image on the right turned up in my Facebook feed, coming from Science Humor.

In case you don't look out for details, the hole that the fly was caught in (or poked into) was actually made by a projectile coming from the other side, so the accompanying question about the fly's speed is, at the very least, just a bit misleading, but somebody is going to cite a legend.

When you enquire about fast animals, more often than not, you will read that the fastest animal of all is the deer botfly, which is credited with an amazing 1287 km/hr, though if you convert this to miles per hour, it comes out as a round 800 mph, a figure that smells a little bit like fudged science—and rightly so.

The story begins with a 1927 article by an entomologist called Charles Henry Tyler Townsend, who reported a speed like this in the Journal of the New York Entomological Society. He actually claimed that the fly was clipping along at 400 yards per second, which works out at 818 mph or 1316 km/hr in metric units. As we will see shortly, any preciseness in the conversion is hardly justified.

Townsend reasoned that these flies passed in a blur, and so must have been travelling very fast. On that scientific basis and no other, he credited them with a nice round 400 yards/second.

That story should have been questioned right away, but people wrote it down, passed it on, quoted it uncritically, and never stopped to wonder what would happen if flies were tearing around at supersonic speeds.

As we will see later (next entry in this blog), some people would stop to prove that the bumblebee could not fly, but nobody stopped to consider and demonstrate the impossibility of the botfly claim until 1938, when Irving Langmuir, a Nobel laureate in chemistry, having given it some thought, tested the assumptions.

First, the air pressure on the fly at that speed would be more than half an atmosphere, surely enough to crush it. The energy needed to maintain the flight would be 370 watts, half a horsepower, which would be quite an ask. Aside from anything else, the botfly would use up its own weight in fuel every second, so it would need to be a voracious feeder.

Next, Langmuir had been hit by these flies, and while it hurt, that weight of fly at 1300 km/hr would have left a significant hole, rather like that of a soft bullet, and the fly would have been mashed inside the wound. Instead, the fly bounced off.

Langmuir mocked up a model of the botfly, using solder to make a pellet that was 1 cm long and 0.5 cm wide. He attached this to a string, and whirled it around his head, timing it so he could work out its velocity. He reported that at 13 mph it was a blur, at 26 mph it was barely visible, at 43 mph an observer could not tell which way it was going, and at 64 mph, it was completely invisible.

He concluded that the blur Townsend had seen came from a fly travelling at 25 mph (40 km/hr). His results were published in Science and reported in Time magazine, but legends are tough things, even when they are debunked by Nobel Prize winners. So even today, the same old values keep emerging from the woodwork.

By a curious chance, Langmuir’s name crept into the record books in an entirely different way in 2006 when plasma physicists used a specially designed holographic-strobe camera to capture pictures of matter waves that were travelling at 99.997% of the speed of light.

Known as Langmuir waves, they are generated by intense laser pulses, and may one day lead to “tabletop” versions of high-energy particle accelerators. One step along the way was taking photographs of the waves to see if they behaved the way scientists thought they would. They did, which is more than we can say about the botfly's behaviour.