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Friday, 11 October 2019

Can we trust statistics?

This chapter began as two radio talks delivered on the ABC, almost thirty years ago. My friend Peter Chubb asked me if I had addressed these issues, and I said that I hadn’t, but that I had provided a link to the text of the talk. Two nights later, I decided to add it, the next night, I rewrote it.
There is enough information here to let readers try the following exercise in Evil Statistics out for themselves.
Boris, Don and Tony went fishing, and caught ten fish. Four weighed 1 kg, two were 2 kg, two were three kg, one was 6 kg, and one was 10 kg. They reported that the average was 1 kg, 2 kg and 3 kg, and all were telling a sort of truth. Boris reported the mode, the most common mass, Don reported the median, the mass of the middle two fish, Tony reported the mean, adding all the masses and dividing by ten. Each value was true, each was different.
It all sounds a bit like “Lies, damned lies, and statistics”, but who first said that? The popular myth is that it was Mr. Disraeli, the well-known politician, but many quite reputable and reliable reference books blame author Mark Twain.
It turns out that it was first published by Twain all right, but Twain attributed the line to Disraeli, and you won't find the story in any earlier publication than Twain's autobiography. In short, Mark Twain made the whole thing up! Disraeli never spoke those words: Twain invented them all, but he wanted the joke to have a greater force, and so gave the credit to an English politician.
Twain wasn't only well-known for his admiration of a good “Stretcher” (of the truth, that is), he even lied when he was talking about lies, and his name wasn't even Mark Twain, but Samuel Clemens! Now would you buy a used statistic from this man?
Last century, when Disraeli is supposed to have made the remark, statistics were just numbers about the State. The state of the State, all summed up in a few simple numbers, you might say.
Now governments being what they are, or were, there was more than a slight tendency in the nineteenth century to twist things just a little, to bend the figures a bit, to bump up the birth rate, or smooth out the death rate, to fudge here, to massage there, to adjust for the number you first thought of, to add a small conjecture or maybe to slip in the odd hypothetical inference.
It was all too easy to tell a few small extravagances about one's armaments capacity, or to spread the occasional minor numerical inexactitude about whatever it was rival nations wanted to know about, and people did just that. Even today, when somebody speaks of average income, if you don’t smell fish, at least remember them, and ask if that’s the mean, the median or the mode.
When I was young, I smoked cigarettes, but the cost and the health risks convinced me, so I stopped, back in 1971. Smokers think we reformed smokers are tiresome people who keep on at them, trying to get them to stop as well.
The non-smokers say those who still puff smoke are the tiresome people, who can't see the carcinoma for the smoke clouds, who deny any possibility of any link between smoking and anything. Like the tobacco pushers, the smokers dismiss the figures contemptuously as “only statistics”. The really tiresome smoker will even say a few unkind things about the statisticians who are behind the figures. Or about the statisticians who lie behind the figures.
By the end of the 19th century, statistics were no longer the mere playthings of statesmen, they were way to clump large groups of related facts into convenient chunks. If you can see how the statistics were arrived at, perhaps you can trust them.
At one stage in my career, I led a gang of people who gathered statistics and messed about with numbers, but we preferred to be called ‘number-crunchers’. People say a statistician is “somebody who's rather good around figures, but who lacks the personality to be an accountant”.
They speak of the statistician who drowned in a lake with an average depth of 15 cm. We are told that a statistician collects data and draws confusions, or draws mathematically precise lines from an unwarranted assumption to a foregone conclusion. They say “X uses statistics much as a drunkard uses a lamp-post: rather more for support than for illumination”.
Crusty old conservatives give us a bad name, pointing out that tests reveal that half our nation's school leavers to be below average, which is true, but it is equally true that the vast majority of Australians have more than the average number of legs. All you need is one Australian amputee!
If somebody does a Little Jack Horner with a pie that's absolutely bristling with statistical items and they produce just one statistical plum, I won't be impressed at all: the plum's rather more likely to be a lemon, anyhow. 
The statistics have to be plausible and significant. Later, I will show you a statistical link between podiatrists and public telephones: this is obviously nonsense, and we will ignore it. There is no logical reason for either to influence the other.
Still, unless there is a plausible reason why X might cause Y, it's all very interesting, and I'll keep a look-out, just in case a plausible reason pops up later, but I won't rush to any conclusion. Not just yet, I won't.
First, I will check on the likelihood of a chance link, something we call statistical significance. After all, if somebody claims to be able to tell butter from margarine, you wouldn't be too convinced by a single successful demonstration, would you? Well, perhaps you might be convinced: certain advertising agencies think so, anyway.
If you tossed a coin five times, you wouldn't think it meant much if you got three heads and two tails, unless you were using a double-headed coin, maybe. If somebody guessed right three, or even four, times out of five, on a fifty-fifty bet, you might still want more proof.
You should, you know, for there's a fair probability it was still just a fluke, a higher probability than most people think. There's about one chance in six of correctly guessing four out of five fifty-fifty events. Here is a table showing the probabilities of getting zero to five correct from five tosses:
zero right
one right
two right
three right
four right
five right

 The clever reader may notice a resemblance to Pascal’s triangle here!
Now back to the butter/margarine study. Getting one right out of one is a fifty-fifty chance, while getting two right out of two is a twenty five per cent chance, still a bit too easy, maybe. So you ought to say “No, that's still not enough. I want to see you do it again!”.
Statistical tests work in much the same way. They keep on asking for more proof until there's less than one chance in twenty of any result being just a chance fluctuation. The thing to remember is this: if you toss a coin often enough, sooner or later you'll get a run of five of a kind.
As a group, scientists have agreed to be impressed by anything rarer than a one in twenty chance, quite impressed by something better than one in a hundred, and generally they're over the moon about anything which gets up to the one in a thousand level. That's really strong medicine when you get something that significant.
There. Did you spot the wool being pulled down over your eyes, did you notice how the speed of the word deceives the eye, the ear, the brain and various other senses? Did you feel the deceptive stiletto, slipping between your ribs? We test statistics to see how “significant” they are, and now, hey presto, I'm asserting that they really are significant. A bit of semantic jiggerypokery, in fact.
And that's almost as bad as the sort of skullduggery people get up to when they're bad-mouthing statistics. Even though something may be statistically significant, that's a long way away from the thing really being scientifically significant, or significant as a cause, or significant as anything else, for that matter.
Statistics make good servants but bad masters. We need to keep them in their places, but we oughtn't to refuse to use statistics, for they can serve us well. Now you are ready to object when I assert that all the podiatrists in New South Wales seem to be turning into public telephone boxes in South Australia, and it all began with Florence Nightingale. Most people think of her as the founder of modern nursing, but as part of that she created ways to use statistics to pinpoint facts.
After her name was made famous, directing nursing in the Crimean war, she returned to London in 1857, and started to look at statistics, and the way they were used. She wrote a pamphlet called “Mortality in the British Army”, and the very next year, she was elected to the newly formed Statistical Society.
She looked at deaths in hospitals, and demanded that they keep their figures in the same way. The Statistical Congress of 1860 had, as its principal topic, her scheme for uniform hospital statistics. It isn’t enough to say Hospital X loses more patients than Hospital Y does, so therefore Hospital X is doing the wrong thing.
We need to look at the patients at the two hospitals, and make allowances for other possible causes. We have to study the things, the variables, which change together. Statistics, remember, are convenient ways of wrapping a large amount of information up into a small volume. A sort of short-hand condensation of an unwieldy mess of bits and pieces.
And one of the handiest of these short-hand describers is the correlation coefficient, a measure of how two variables change at the same time, the one with the other. Now here I'll have to get technical for a moment. You can calculate a correlation coefficient for any two variables, things like number of cigarettes smoked, and probability of getting cancer.
The correlation coefficient is a simple number which can suggest how closely related two sets of measurements really are. It works like this: if the variables match perfectly, rising and falling in perfect step, the correlation coefficient comes in with a value of one. But if there's a perfect mismatch, where the more you smoke, the smaller your chance of surviving, then you get a value of minus one.
With no match at all, no relationship, you get a value somewhere around zero. But consider this: if you have a whole lot of golf balls bouncing around together on a concrete floor, quite randomly, some of them will move together, just by chance.
There’s no cause, nothing in it at all, just a chance matching up. And random variables can match up in the same way, just by chance. And sometimes, that matching-up may have no meaning at all. This is why we have tests of significance. We calculate the probability of getting a given correlation by chance, and we only accept the fairly improbable values, the ones that are unlikely to be caused by mere chance.
We aren’t on safe ground yet, because all sorts of wildly improbable things do happen by chance. Winning the lottery is improbable, though the lotteries people won't like me saying that. But though it's highly improbable, it happens every day, to somebody. With enough tries, even the most improbable things happen.
So here's why you should look around for some plausible link between the variables, some reason why one of the variables might cause the other. But even then, the lack of a link proves very little either way. There may be an independent linking variable.
Suppose smoking was a habit which most beer drinkers had, suppose most beer drinkers ate beer nuts, and just suppose that some beer nuts were infected with a fungus which produces aflatoxins that cause slow cancers which can, some years later, cause secondary lung cancers.
In this case, we'd get a correlation between smoking and lung cancer which still didn't mean smoking actually caused lung cancer. And that's the sort of grim hope which keeps those drug pushers, the tobacco czars going, anyhow. It also keeps the smokers puffing away at their cancer sticks.
It shouldn't, of course, for people have thrown huge stacks of variables into computers before this. The only answer which keeps coming out is a direct and incontrovertible link between smoking and cancer. The logic is there, when you consider the cigarette smoke, and how the amount of smoking correlates with the incidence of cancer. It's an open and shut case.
I'm convinced, and I hope you are too. Still, just to tantalise the smokers, I'd like to tell you about some of the improbable things I got out of the computer in the 1980s. These aren't really what you might call damned lies, and they are only marginally describable as statistics, but they show you what can happen if you let the computer out for a run without a tight lead.
Now anybody who's been around statistics for any time at all knows the folk-lore of the trade, the old faithful standbys, like the price of rum in Havana being highly correlated with the salaries of Presbyterian ministers in Massachusetts, and the Dutch (or sometimes it's Danish) family size which correlates very well with the number of storks' nests on the roof.
More kids in the house, more storks on the roof. Funny, isn't it? Not really. We just haven't sorted through all of the factors yet. The Presbyterian rum example is the result of correlating two variables which have increased with inflation over many years.
You could probably do the same with the cost of meat and the average salary of a vegetarian, but that wouldn't prove anything much either. In the case of the storks on the roof, large families have larger houses, and larger houses in cold climates usually have more chimneys, and chimneys are what storks nest on. So naturally enough, larger families have more storks on the roof. With this information, the observed effect is easy to explain, isn't it?
There are others, though, where the explanation is less easy. Did you know, for example, that Hungarian coal gas production correlates very highly with Albanian phosphate usage? Or that South African paperboard production matches the value of Chilean exports, almost exactly?
Or did you know the number of iron ingots shipped annually from Pennsylvania to California between 1900 and 1970 correlates almost perfectly with the number of registered prostitutes in Buenos Aires in the same period? No, I thought you mightn't.
These examples are probably just a few more cases of two items with similar natural growth, linked in some way to the world economy, or else they must be simple coincidences. There are some cases, though, where, no matter how you try to explain it, there doesn't seem to be any conceivable causal link. Not a direct one, anyhow.
There might be indirect causes linking two things, like my hypothetical beer nuts. These cases are worth exploring, if only as sources of ideas for further investigation, or as cures for insomnia. It beats the hell out of calculating the cube root of 17 to three decimal places in the wee small hours, my own favourite go-to-sleep trick.
Now let's see if I can frighten you off listening to the radio, that insomniac's stand-by. Many years ago, in a now-forgotten source, I read that there was a very high correlation between the number of wireless receiver licences in Britain, and the number of admissions to British mental institutions.
At the time, I noted this with a wan smile, and turned to the next taxing calculation exercise, for in those far-off days, all correlation coefficients had to be laboriously hand-calculated. It really was a long time ago when I read about this effect.
It struck me, just recently, that radio stations pump a lot of energy into the atmosphere. In America, the average five-year-old lives in a house which, over the child's life to the age of five, has received enough radio energy to lift the family car a kilometre into the air. That's a lot of energy.
Suppose, just suppose, that all this radiation caused some kind of brain damage in some people. Not all of them necessarily, just a susceptible few. Then, as you get more licences for wireless receivers in Britain, so the BBC builds more transmitters and more powerful transmitters, and more people will be affected. And so it is my sad duty to ask you all: are the electronic media really out to rot your brains? Will cable TV save us all?
Presented in this form, it's a contrived and, I hope, unconvincing argument. Aside from anything else, the radiation is the wrong wave-length and cannot change any cells. My purpose in citing these examples is to show you how statistics can be misused to spread alarm and despondency. But why bother?
Well, just a few years ago, problems like this were rare. As I mentioned, calculating just one correlation coefficient was hard yakka in the bad old days. Calculating the several hundred correlation coefficients you would need to get one really improbable lulu was virtually impossible, so fear and alarm seldom arose.
That was before the day of the personal computer and the hand calculator. Now you can churn out the correlation coefficients faster than you can cram the figures in, with absolutely no cerebral process being involved.
As never before, we need to be warned to approach statistics with, not a grain, but a shovelful, of salt. The statistic which can be generated without cerebration is likely also to be considered without cerebration. Which brings me, slowly but inexorably to the strange matter of the podiatrists, the public telephones, and the births.
Seated one night at the keyboard, I was weary and ill at ease. I had lost one of those essential connectors which link the parts of one's computer. Then I found the lost cord, connected up my computer, and fed it a huge dose of random data.
I found twenty ridiculously and obviously unrelated things, so there were one hundred and ninety correlation coefficients to sift through. That seemed about right for what I was trying to do.
When I was done, I switched on the printer, and sat back to wait for the computer to churn out the results of its labours. The first few lines of print-out gave me no comfort, then I got a good one, then nothing again, then a real beauty, and so it went: here are my cunningly selected results. I have simply used, for good reasons, the methods of the crooks and con-men.

Tasmanian birth rate
SA public phones
NSW podiatrist registrations
Tasmanian birth rate
SA public phones
NSW podiatrist registrations

Well of course the podiatrists and phones part is easy. Quite clearly, New South Wales podiatrists are moving to South Australia and metamorphosing into public phone boxes. Or maybe they're going to Tasmania to have their babies, or maybe Tasmanians can only fall pregnant in South Australian public phone booths.
Or maybe codswallop grows in computers which are treated unkindly. Figures can't lie, but liars can figure. I would trust statistics any day, so long as I can find out where they came from, and I'd even trust statisticians, so long as I knew they knew their own limitations. Most of the professional ones do know their limitations: it's the amateurs who are dangerous.
I'd even use statistics to choose the safest hospital to go to, if I had to go. But I'd still rather not go to hospital in the first place. After all, statistics show clearly that more people die in the average hospital than in the average home.
The original version is here:

Monday, 7 October 2019

Science Playwiths 1.

I am about to sign a contract for a new book which I want to be called Science Playwiths, because it originated in a long-running web site of that name. It covers STEAM: Science, Technology, Engineering, Arts and Mathematics. Here's a first sample, about curious number facts.
One estimate of the size of the entire universe puts its radius at 3 x 1023 times larger than the size of the observable universe. That is almost exactly half the value of Avogadro’s number, which every good chemist knows to be 6.022 x 1023. So what?
The speed of light in terafurlongs per fortnight is 1.803, close enough for government work to the metric equivalent of a fathom, showing that any measured value can be given almost any number by a cunning choice of units. Any reasoning based on the coincidence of two values needs to be questioned closely to see if the coincidence is just, well, a coincidence—or the work of somebody using peculiar units to get a result.
For example, the number of islands in the Hawaiian island chain is 137, and the ratio 1/137, often referred to as alpha, is the fine structure constant in physics. This value represents the probability that an electron will emit or absorb a photon. It is the square of the charge of the electron divided by the speed of light times Planck’s constant, and it is just a number: there are no dimensions or units involved at all.
The significance of alpha was first spelled out in 1915 by a physicist named Arnold Sommerfeld—at the time, measurement errors made the value closer to 136—and physics ever since has been littered with efforts to explain the number.
The most famous attempt was that of Sir Arthur Eddington, a prominent astronomer who believed that such constants could be used to produce a theory of the universe. He built a huge 16-dimensional equation full of these constants and claimed that alpha could be calculated from the number of terms: (162 - 16)/2 + 16, or 136.
Unfortunately, experiments quickly showed that alpha was really closer to 137. Eddington was not dismayed. He said he had forgotten to add one more factor, alpha itself, and made the value 137. For this, Punch magazine dubbed him Sir Arthur Adding-One.
Eddington was not deterred. Proudly he proclaimed that the firmament contains exactly (137 - 1) x 2256 protons. In 1938, he declared:
I believe there are 15 747 724 136 275 002 577 605 653 961 181 555 468 044 717 914 527 116 709 366 231 425 076 185 631 031 296 protons in the universe and the same number of electrons.
Of course, he may have been right; I have not yet been able to count them all, and it’s hard enough trying to find the value of 2256.

Saturday, 28 September 2019

The first signs of spring

The pedants say we should wait until the first day of September to claim a true spring, but nobody ever told that to a body of water in the mid-Pacific, called El Niño.  This warm wet blob causes profound effects in our weather, and pays no attention to seasons at all.  Instead of having seasons, Australians have the El Niño cycle of flood and drought.  But if we ever have a spring at all, it truly begins somewhere in early August, and drifts into low summer soon after.

Early August is the flowering time for many bush wildflowers, the native flowers that cover our headlands and national parks.  August 1 has always been the traditional day to go out and admire the wattle trees, so it is no surprise to find them flowering, but a minute's searching can detect a dozen other species in five different families, in the bush just behind my house.  Even the imported plants, the magnolias and the flowering peaches and cherries are in full flower, and the first clover flowers are showing up in our lawn by the start of August, to the delight of the bees. Now, in late September, as I write this, the plants are all setting their seed.

Last Sunday, I went for a walk on a local beach.  As I expected, several local teenagers were in the water, boogie-boarding in wet suits, but I was a little surprised to see two more just swimming in the ordinary way, wearing normal swimming costumes.  We breed our kids tough!!

The best indications of promise come from the television, full as it is with football finals fever.  There are four main codes of football in Australia: Rugby League and Rugby Union, soccer (just 'football' to its adherents) and ‘Aussie Rules’, a sort of Gaelic football played 18 a side with eight goal posts.  There is also a bit of Gaelic football here and there, and rather more gridiron.  Each of these codes is reaching season's end, and so the TV news each night is full of rivetting facts about this player's groin injury, that one's hamstring, and the other's suspension for dangerous play.  Once we are free of football, then summer must be here. One more week, and that will be gone.

I drive every Tuesday morning on winding roads, so I am very aware of the sun's annual movements.  No longer does it shine straight down one hill near the sanctuary that I must climb in the morning, for the morning sun was already drifting south along the horizon by August, and now it is high enough in the sky to be behind a tree as I tootle up the hill at 7.30 am.

Our sunrise varies between 7 in winter and 5 in summer, while sunset is between 5 pm and 7 pm (ignoring daylight saving, that is).  By late August, the sunrise is  a minute earlier each day, and sunset is a minute later, so clearly we are over the hump. After October 20, the pace slows down.

An image from my book, Australian Backyard Earth Scientist. This shows sunset movement, close to the solstice.

By late August, the signs of spring were all round us.  Suburban parents send their younger children out wearing plastic ice-cream containers on their heads, with two eyes drawn on the back.  Magpies are beginning to stake out their nesting territories, and children can be pecked on the head quite painfully.

But the best sign that spring is truly sprung comes when we see fifty thousand sweaty, liniment-reeking Australians, all heading from the centre of the city to Bondi Beach in the annual ‘City to Surf’ run. That happens in mid-August.

This race begins almost outside Hyde Park.  Each year in the 1990s, two hundred sensible hedonists gathered on the museum's roof top for a champagne and croissant breakfast, arranged by the Australian Museum Society, one of my favourite organisations.  As sports-loving Australians, of course, we watched the start of the race first, to build up our appetite for breakfast.  The champagne would take a punishing during this gruelling period, but we remain respectfully hungry.

I travelled to town on an early ferry one morning six weeks back with my wife, and strolled up to the museum, through streets unusually full of Lycra and Reeboks. In the past, she has been known to run in the race, though a long-lasting injury has put her out, at least for this year, but she offered me some insights about what goes on when you are on the inside of the Gallant Hundred Thousand (I may be exaggerating: it may be only 70,000).

All competitors are colour-coded, she explained, pointing to the number on a 70-year-old matron trotting past us.  She was a blue, one of the ‘runners’.  Out front, we have the super-elite, people in the top ranks for marathon and half-marathon running.  Just behind them, are the ordinary elite, people who have previously run the 12 km City to Surf in good time. Then come the rest of those entering as ‘runners’, which is where our matron would have been.  There are probably 12 or 15 thousand runners in all, and they start first, led by the elite group.

In a street to the right, there are about the same number of ‘joggers’.  In this area, you will usually find a trio in gorilla suits, four men wheeling a refrigerator, a medical group wheeling a hospital bed, Coke cans, giant grains of rice, and other novelty groups, as well as some serious parents pushing strollers and prams at the jog, and some teenagers.

These classifications are a bit rough and ready, for there are always a few break-away joggers who dash out at the second gun, and quickly begin overhauling the last of the runners, but these are a cut above the ‘walkers’.

Finally, out to the left, are the 20-25 thousand walkers, many of whom run out at the third gun to start working their way up through the joggers.  Many of these are on their first attempt, and will move into higher ranks in later years, but there are also wheelchair pushers here, more parents with prams and strollers, and kids aged from about ten up, running in their own right.  This year, there was also a large group of fat people waddling along, carrying helium balloons.  My wife thought it was to camouflage their obesity, but I think they were hoping to take some of the weight off their feet.

Fifty thousand people make a lot of noise, especially when they cheer together.  They are a good-spirited crowd, and an hour before the start, the walkers were gathered in their starting area.  Soon, four inflated balls were bouncing around over the crowd, continually pushed aloft by willing hands.  If a ball went beyond their area, a marshal would run to retrieve it, and send it back into the crowd again.

Time passed, and people started to warm up in the three seething masses.  Soon sweat shirts, jumpers, and other forms of top cover were taken off and thrown to the sides of the eight-lane roadway.  People wear old ‘discardables’, and you just throw towards the nearest side.  Those closer to the sides take anything that lands on them, and throw it further to the side.  Just before the race, you look down on a sea of faces, with items of clothing leaping in graceful parabolas over the surface, like a school of mullet pursued by a large hungry fish.  Now they are in their racing finery, numbers pinned to their chests.

At the first gun, the runners start, as the marshals who have been standing in front of them sprint to safety at the roadside.  The lesser groups cheer, and then all is silent as they head downhill.  Silent, that is, except for about 30 000 running shoes pattering on the tar surface, which sums to an almost deafening roar. Before the last runners pass the start line, the leaders have reached the valley below, climbed the other side, and headed into the Kings Cross tunnel that leads to the next downhill run.

As the last runners clear the intersection, the joggers have their start, and soon after, the walkers take off.  Ten minutes later, as the last walkers cross the start line, the sweeping machines move in to clear up.  By the time the last Irish dancing team has jigged over the start line, stopping frequently to pose for the curious cameras wielded by swarms of shutter-hungry and bemused Japanese, the first runners have climbed Heartbreak Hill, and they are through the pain barrier at the half-way point.

By the time the last walkers reach the tunnel, the sweeping machines at the start line are done, the barricades are cleared, traffic is back to normal, and the first runner is already pushing through the tape at Bondi, 12 km and 42 minutes away.  People will continue to straggle into Bondi for around three hours more, and there will probably be forty thousand finishers.

As they run, they will pass below a number of cameras mounted strategically over the road, and are photographed from a position which shows their entrant numbers.  In a few weeks, letters will arrive in the mail telling people that there is a delightful picture of them, taken at _____, and available for the surprisingly small fee of $25.  I asked my wife if she had ever bought one.  No, she said: who would want a picture of one's self all hot and sweaty.  Of course, she adds, if it were a group picture, it would make a nice keepsake.  I detect an impending threat, and I am right.

Next year, she says , we will join the walkers as a family team.  I spread more jam on my croissant and say nothing.  I will walk 40 km in a day with a medium load, but only in wilderness.  If I want to be in a crowd, I will take the 200 with their champagne and croissants, not the fifty thousand in liniment, Lycra and Reeboks in the street below.  I decide to change the subject: ‘Look over the road,’ I tell her.

In the park opposite, Sydney's homeless emerged from the undergrowth to pick over the discarded clothing.  Two of the better organised had a long pole that they used to drag the more attractive items out of the trees along the road's edge.  Still, now that summer is coming, they will have less need of extra clothes.

Saturday, 21 September 2019

When the going gets tough...

... the tough go shopping. This is an excerpt of chapter 6 in the same project, and by now, the perceptive reader should have worked out the thrust...

The convicts in general had suffered much through want of clothing and bedding. Indeed, during the late harvest, several gangs were seen labouring in the fields, as free of clothing of any kind as the savages of the country.
—David Collins, An Account of the English Colony in New South Wales, volume 2, 102.

As a rule, everybody needed clothes, and there were set rations, if you were dependent on the Crown. As early as 1804 (though the rules were probably older), the clothing to be provided to convicts was laid down in regulations:

The following Proportion of Cloathing will be issued in future to those at Public Labour, about the 25th of December and the 4th June annually, when the Store will allow of that Distribution viz.
December for each Man 1 Frock, 1 Shirt, 1 Pair of Trowsers, 1 Pair of Breeches, and 1 pair of Shoes;
June For each Man 2 Jackets, 2 Shirts, 1 Pair of Trowsers or Breeches, 1 Hat, and 2 Pair of Shoes. [1]

Just over a year later, there was an issue of “slop clothing” in Sydney. This was a common term in the Royal Navy and also in the colony, where slop or slops meant generic clothing. In 1805, readers of the Gazette saw that there was to be an issue of “Slop Cloathing”:

To Overseers—One Pair of Shoes, two Shirts, one Pair of Trowsers, and a Hat.
To Male Prisoners—A Frock, Shirt, Pair of Trowsers, and Hat.
To Female Prisoners at Public Labour—A Jacket, Petticoat, Shift, Cap, Handkerchief, and Pair of Stockings.
The former Orders, forbidding the Purchase or Disposal of Slop Cloathing issued to Prisoners at Public Labour, remain and continue in force. [2]
Anna Lewin’s advertisement: many items under one roof.  [3]

The honest folk, those not entitled to a handout of slops from the government, went to shops like the one run by Anna Lewin the wife of painter John Lewin. This carried many products (although the reference to ‘gunpowder’ means a type of tea that resembles gunpowder, not the stuff used in muskets).

No shopkeeper could afford to be a specialist when cargoes took three to six months to arrive, or even more, and they would buy anything that would sell. The three advertisements that follow appear in this order on the same page in a single issue of The Sydney Gazette and New South Wales Advertiser, in January 1810. [4]

For Sale by Thomas Abbott, Corner of Barrack Row, frilled shirts 7s. each, Bandanna handkerchiefs 3d. per piece; plain shirts 6s. 6d. each, good tobacco 2s. 3d. per lb. by the basket, sugar 13d. per lb. by the bag, and 12d. per lb. by the ton, yellow soap 2s. 3d. per lb. superfine broadcloths 10s. per yard; printed cambrick by the piece 6s. per yard, check shirts 7s. each, longcloth, 26 yards to the piece, at £7, coffee and tea, flat irons and iron pots 7d. per lb. threads by the lb. and tapes by the dozen, and a variety of other Articles…

John Driver in Chapel Row had even more varied stock:

…Irish linen coarse and fine, black cambrick and capital bombazeens for mourning dresses, toys in great variety, artificial flowers, ladies’ coloured silk bands and tassels, ear and finger-rings, gold lace, knives and scissars, gilt, shirt, and cambrick buttons, gloves, stockings, spy-glasses, writing, paper, pins, needles, thread, sewing cotton, best Hyson tea, common ditto, soap, vinegar, decanters, wine glasses, rummers, tumblers, dishes, plates, mugs, basons, black and coloured silk handkerchiefs, muslin ditto, veils, cambrick muslins,…India muslin, large elegant shawls of superior quality, shoes and boots, sugar candy, pepper, ginger, beans, dried fruits, and many other articles…

Michael Hayes was a leather specialist, but like the other merchants, he was willing to sell anything else that could be obtained, and soon after this advertisement appeared, he was also allowed a wine and spirit licence.

ON Sale, at the warehouse of M. Hayes, an extensive assortment of Leather; consisting of Morocco and Spanish coloured skins, English tanned seal leather and wax calf skins, seal skins, cordovan, brown and white sheep skins, Hessian boot legs boots and shoes, boot top leather, ladies and children’s shoes of all colours, russet calf skins for ladies’ shoes; Also, a variety of other Goods, consisting of cloths, prints, linens, stuffs, calicoes, shawls, teas, sugar, wines, &c. &c. as well as a variety of brass wares.

Over time, some merchants began to specialise, and by the 1840s, much of George Street in Sydney was given over to shops. Louisa Meredith said it was about a mile and a half (2 km) long, with good shops offering all sorts of merchandise.

One long street traverses its whole length, about a mile and a half, full of good shops exhibiting every variety of merchandise; and in the afternoon, when the ladies of the place drive out, whole strings of carriages may be seen rolling about or waiting near the more “fashionable emporiums,” that being the term in which Australian shopkeepers especially delight. [5]

I have heard it asserted (but cannot now find a source for it) that in the early days, men working in paddocks would wear just a long shirt in order to keep cool. An article on the governor’s expenses, taxes and the cost of rum in The Monitor in 1828 refers to agricultural workers’ removing their shirts when labouring.

…the shearers of the harvest of this Colony…when, sweating under an almost vertical sun, with their backs burnt (as we have often seen them) as deep in colour as a cake of patent chocolate…the above-mentioned mahogany-backed shirtless reapers…[6]

[1] The Sydney Gazette and New South Wales Advertiser, 15 January 1804, 1,
[2] The Sydney Gazette and New South Wales Advertiser, 3 February 1805, 1,
[3] The Sydney Gazette and New South Wales Advertiser, Sunday 12 June 1808, 2,
[4] The Sydney Gazette and New South Wales Advertiser, 21 January 1810, 4,
[5] Louisa Ann Meredith, Notes and Sketches of New South Wales, 38.
[6] The Monitor (Sydney), 14 May 1828, 4,

Tuesday, 10 September 2019

What geologists think, part 3

8. The standard principles of science

These are ideas that all scientists just assume, but they are rarely stated explicitly for students or the public. There is enough information here to tell you what each idea is about, and you will find enough terms to let you look the idea up, if you need to. There are lots of ins and outs, and working scientists spend their lives mastering them. They will, I hope, recognise that this is Science Lite.

Atoms and molecules

All matter is made up of atoms, and the properties of any piece of matter will depend on what atoms are present, and how they are arranged and connected. Many atoms join up to form regular frameworks that we call crystals. Sometimes, atoms join into tight standard groups, like water, quartz, salt and sugar. We csll these groups molecules.

The laws of thermodynamics

For general purposes, heat flows from hot to cold, perpetual motion is impossible, and there is no such thing as a free lunch. By the way, if you want to drive a politician or an arts administrator to distraction, ask him or her to explain (or even just to state) the second law of thermodynamics. Trust me: it matters!
A good many times I have been present at gatherings of people who, by the standards of the traditional culture, are thought highly educated and who have with considerable gusto been expressing their incredulity at the illiteracy of scientists. Once or twice I have been provoked and have asked the company how many of them could describe the Second Law of Thermodynamics. The response was cold: it was also negative. Yet I was asking something which is the scientific equivalent of: Have you read a work of Shakespeare’s?
—C. P. Snow, Rede Lecture The Two Cultures and the Scientific Revolution (1959).
 If you want a simple version, it says that differences in temperature, pressure, and density tend to even out, after a while. More detailed discussion involves entropy The simplest available version of that: entropy is a thermodynamic function that measures randomness or disorder. If you like, entropy is a measure of untidiness.
Most of the principles of science are what scientists call counter-intuitive. In lay terms, they seem to go against our gut reaction; the earth as we experience it looks flat, and our intuition tells us the sun and moon circle around us once a day, but ignoring intuition, all scientists agree that the world is a globe, we orbit around the sun, and the moon orbits around us once a month.

Entropy is slippery, rather than counter-intuitive, and you have to note the qualifications which limit entropy to inside a closed system. Under those conditions, entropy, or disorder, increases, which is how scientists say that over time, everything gets more random, more dispersed.

There can be no exceptions to the rule that entropy, the disorder of things, always increases, but life, at a local level, can be an anti-entropy agent, making some things more ordered at a local level, even as entropy is increasing on a larger scale. In simple terms, animals and plants gather up and concentrate certain elements in our bodies.

Across the universe, every change leads to an increase in the total entropy, but the delight lies in the details, and a lot of geological science comes down to explaining how, on a local level, the process of concentration in elements or minerals is driven.
If [your pet theory of the universe] is found to be contradicted by observation—well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.
—Sir Arthur Stanley Eddington, The Nature of the Physical World (1928), chapter 4.

Conservation of mass and energy

In simple terms, matter and energy can neither be created nor destroyed. There is No Such Thing As A Free Lunch.


As a rule, things are in balance, but that is not the same as saying they are unchanging. The number of oxygen molecules in an open jar may vary slightly over time, as molecules whizz in and out, but at any practical level, the entries and exits cancel each other out. If I have crystals of salt sitting in a saturated brine solution, some of the chloride and sodium ions in solution may attach to the crystals, but on average, just as many ions will leave the crystals. We say the solid and the solution are in dynamic equilibrium.

The law of large numbers

There is no such law, but it is convenient to pretend that it exists. Given time, every atom of a sample of radioactive carbon-14 will break down. We cannot say when a given atom will decay, but with large numbers of atoms, we can say that half of all of the atoms that we start with now will have decayed if we come back in 5730 years from now. We say that carbon-14 has a half-life of 5730 years.


Evolution also hangs on large numbers. You won’t evolve, I won’t evolve, but our species, like every other species, does evolve. Don’t worry: some of your genes will carry forward, and some of them may be more common in a future population.

(I anticipate, for example, that in a thousand years, the descendants of today’s Australians will have a skin color darker than mine, due to the selective effects of melanoma.)

(Note that this can  be negated because humans, uniquely in an evolving world, can apply social changes to limit selection effects.)


Every part of science is able to be falsified by evidence, and if some idea can’t be tested and potentially falsified, it just isn’t science. That doesn’t mean science is all false, it just means every assumption is always considered open to testing and being found wrong.

If we found dinosaur fossil bones and human fossil bones in the same rock, this would mean we probably had to revise large parts of what we think we know about geology and biology, though the first step would be to check carefully that somebody hadn’t just pulled off a hoax.

Scientists are always on the alert for contradictions like that, even though they don’t really expect to find any. One way to become a famous scientist is by finding a red-hot contradiction to what everybody believes.

Ockham’s Razor

Then again, maybe we wouldn’t need to revise anything. William of Ockham made it a lot more complicated, but his basic notion was that if there are two possibilities, you should take the simpler one. If we found human and dinosaur fossils in a single rock, a simpler explanation would be fraud. We would at least look for evidence of fraud first, but if there was truly no evidence of fraud, it might be time to start a rethink.

9. Caveats

I am not a geologist, but I know how to think, where to look, and what questions to ask. My undergraduate studies were mainly in the areas of botany and zoology, so I may, from time to time, be in error. As a professional science writer, I am used to checking my facts, but even when I get the latest opinions there is still one gotcha remaining.

Science changes, and geological science does change—and I saw it happen. When I was an undergraduate, I picked up one year of formal geology training, enough to appreciate that the rocks yield the soil that my precious plants flourish in, plants that feed my equally precious animals.

One day, one of our geology lecturers urged us to attend certain sessions of ANZAAS, the Australian and New Zealand Association for the Advancement of Science. “Listen to Sam Carey,” he told us. “He’s quite mad: he thinks the continents are moving.”

That was in 1962, and I did indeed hear Sam Carey talking about such wild ideas. He seemed to make a reasonable case, except that we all knew the idea was crazy. Just three years later, plate tectonics was all the go.

In fairness, Sam Carey was only partly right, because his notion was based on some false assumptions, but the key thing to note is this: in 1962, moving continents was madness, by 1965, it was pretty much the orthodox model.

I have tried in this book to stay with the best and safest bits of orthodoxy, but at any time, that which was orthodox can be defeated of overturned by a simple paradox. One new discovery is all it takes, as T. H. Huxley said while discussing historical work on the spontaneous generation of life:
But the great tragedy of science—the slaying of a beautiful hypothesis by an ugly fact—which is so constantly being enacted under the eyes of philosophers, was played almost immediately, for the benefit of Buffon and Needham.
—T. H. Huxley, Presidential address to the British Association in September, 1870.
My book (meaning Not Your Usual Rocks, still to be published) is about the facts—though I will later discuss a maverick theory about the origins of oil. I don’t believe it, but it is both entertaining, and instructive to consider as a way of seeing how science works.

By the time you are done, all of these will make perfect sense.