A changing climate

Jens Galschiot’s installation
‘Unbearable’ in Copenhagen.

 In the savage illustration on the left, the J-curve skewering the polar bear reflects the graph of the unstoppable rise of atmospheric carbon dioxide, and the curve is made from lengths of oil pipe. Sometimes, art and politics go together very well.

Did you know scientists knew about global warming, well before we usually think? Today, reputable atmospheric scientists everywhere are certain that human activity is driving the modern changes in our climate, but in 1950 it was just a curiosity. Of course, ‘global warming’ is a bad description, so we call it ‘climate change’ now. Under any name, it’s the same beast, the same looming disaster, and we knew about it, two thirds of a century ago.

Nobody denies that the Earth is getting warmer, because the evidence is there, and it was apparent in 1950, when George Kimble reported in Scientific American that the northern limit of wheat-growing in Canada had moved northward some 200 to 300 miles (call it 400 kilometres), adding that farmers in southern Ontario were experimenting with cotton. While cotton seems not to have taken off there, he reported another trend that continues to this day, the northward retreat of the permafrost:

In parts of Siberia the southern boundary of permanently frozen ground is receding poleward several dozen yards per annum.

Was it a cycle? Kimble said the Domesday Book featured 38 vineyards in England in 1086, in addition to those of the Crown. He pointed also to the Greenland colony which was frozen out, back around the mid-1400s and other evidence that climates change. He looked at Biblical evidence on the distribution of date palms to show that conditions in 1950 were much those of Biblical times, providing a picture of a climate that fluctuates around a mean. Maybe the trends were all just part of one of those cycles.

Mind you, the knowledge that humans are to blame is even older, because the whole thing had been predicted. The problem before was that there was not a lot of hard science in the arguments, which come down to logic, reason, careful modelling—and interpretation that was likely to be biased by a generous serving of self-interest. That changed in the last ten years.

Before ‘global warming’, climate change was called ‘the greenhouse effect’. In cold climates, a greenhouse is a glass shed which lets sunlight shine in, where much of the radiation is absorbed and changed to heat. Glass is less transparent to heat, but a greenhouse does more than trap warmth that way: it also holds a body of warm air around the plants, and protects them from wind-driven evaporation. So while we still speak of ‘greenhouse gases’, it is rare to hear anybody mention the greenhouse effect these days, even if the term goes way back to those early predictions.

Still, 1950 wasn't when it all began. In the 1820s, Joseph Fourier realised that heat-trapping might occur. In 1896, Svante Arrhenius reminded us that both water vapour and carbon dioxide were ‘greenhouse gases’ (escaping that bad analogy is hard) and so water and carbon dioxide would play a role in making the planet warmer. 

He also considered changes that might be happening, and consulted Arvid Högbom, who just happened to know all about carbon dioxide sources and sinks. Carbon dioxide was coming from life forms when they breathed, from volcanoes, and from humans burning fossil and other fuels. The human additions were minimal, perhaps one part in a thousand was added by the burning of coal, and there were probably checks and balances. 

Let's say 1896, OK? I mean, that was the story, I thought, but in late March 2019, a circular from Rush Holt at the American Association for the Advancement of Science (AAAS, of which I am a member) drew my attention to Eunice Foote:

Let me add one interesting historical note that is not widely known. In 1856 at the AAAS Annual Meeting, the work of Eunice Foote was presented, showing that carbon dioxide is a heat-blanketing greenhouse gas that in the atmosphere could warm the Earth. This was years before the work of the men usually credited with the finding (Tyndall in England and Arrhenius in Sweden).

Well, that broke into my weekend a bit. Foote’s short piece in The American Journal of Science and Arts in 1856 begins on p. 382, and says: “An atmosphere of that gas [carbonic acid, CO₂] would give our earth a high temperature …”

Arrhenius thought it would take 3000 years to double the atmospheric CO₂ levels, if ever, but such a doubling would raise world average temperatures by 5 to 6°C. In 1896, when Arrhenius did his calculation, the CO₂ level was around 290 parts per million: in 2021, the value was estimated at 420 parts per million: we had travelled almost half of the projected distance in just 125 years. Now look at the angle of that pipe, the one skewering the bear!

To Europeans in the 1890s, the warming effect seemed nothing to worry about, because nobody had stopped to consider the cascades, the flow-ons that might be driven by that rise in temperature. A German chemist, Walther Nernst, even asked if it would be feasible to set fire to uneconomical and low-grade coal seams, so as to release enough carbon dioxide to warm the Earth’s climate deliberately!

In the 1990s, global warming was in much the same position that “continental drift” had been in, a generation earlier, with some of the scientists arguing furiously, even when they agreed on the main principles, and as in the puzzle of the wandering continents, the key evidence was right there. Mind you, when I covered the 2002 Spring Conference of then American Geophysical Union, there were no nay-sayers there. The problem is that so long as people can get away with saying “global warming”, we are once again stuck with a bad label, just as the early 1960s saw us hung up on “continental drift”.

The cost of disagreement and bickering is much higher with climate change. It mattered not at all if people disagreed about plate tectonics (except, perhaps, that it makes tsunamis like the 2004 Indian Ocean tsunami easier to understand), but under any name, global warming is likely to be a major disaster for humanity, and any delay has the potential to cost lives. To understand this, we have to accept some puzzling propositions.

The formation of sea ice in the northern Atlantic is probably what stops Dublin’s and New York’s ports being iced-in each winter. This is because the sea ice is largely free of salt, leaving a residue of cold brine that drives a current known as the Conveyor, which in turn drives the Gulf Stream. The Gulf Stream takes warm water from the Caribbean and swirls it up around the North Atlantic, contributing to fogs and breaking icebergs loose, but keeping northern ports warm and open, even in winter.

Just as the prion proteins of mad cow disease have more than one stable form, so do weather patterns, and if the weather once drops into a new stable pattern, we may not be able to bounce it back to where it started. Then again, as northern Europe freezes over, the fast-melting glaciers will be replenished, lowering sea levels. The increased snow cover will also increase the reflectivity of the northern hemisphere, and that may cool the planet down a little. We just have to hope it does not trigger a new stable pattern that happens to be an ice age.

The changes that might follow the breaking point are hard to predict. They are unlikely to be spectacular and major, and will probably act stealthily, when infrastructure, port facilities and cities are flooded, or when agricultural land is lost, either by being covered by the sea or as a result of drastically changed rainfall patterns.

If any significant amount of rock is exposed in Antarctica, this could lead to a low pressure zone over the icy continent that could change weather patterns around the world. It hasn’t happened yet, but we need to learn from history. Ten years ago, no politician would take a long-term view and force the changes needed in the next thirty to forty years, when most of them are elected for a mere three to four years, after which they have to face the voters again.

It’s easier to bleat plaintively that there is no real agreement among the scientists yet (even if there is), or that some eminent scientists believe in other explanations (they aren’t all that eminent: just look at where the funding of these “scientists” comes from). That load of bollocks saves the politicians from having to act—and the honesty of scientists in saying that they cannot be sure just how things will go wrong allows devious short-term opportunists to prate that “the scientists don’t know…”

Politics is a marvellous human discovery. It is a pity that politicians have yet to discover humanity and consider its prospects. It is likely that politics, dithering, duck-shoving and shilly-shallying will make this disaster happen. So long as the electorate value their comfort right now over the comfort of their grandchildren, they are doomed.

We must care about the young: they are delicate. I will turn to how the young develop next.

The case of the echidna's hind leg

 My friends and some careful readers may be aware that for the first half of this year, I have been engaged in writing about echidnas.

I explained how this came about in April, but I will add it here to save readers leaping around. I am a biologist by training, later a teacher and museum educator, and I now volunteer on land care in a sanctuary on Sydney's North Head. That said, I am best known as a writer of non-fiction for children, and it was in that role that I spoke in December 2020 at a kids’ lit function, where I described the adventures I had while rescuing an echidna from a locked drain in the sanctuary, a drain that was due to flood, that night.

It involved kneeling on a steel grille, handling a heavy, spike-covered echidna that was grimly hanging onto a steel ladder, putting me at risk of toppling head-first into a water-filled sump, but it was still amusing in hindsight.

Over coffee afterwards, three writer friends asked me, separately and within the space of a couple of minutes, if I was planning a book on practical echidna work for younger readers. My answers were, respectively, “Naaah”, “Maybe” and “You betcha!” My third and most convincing interlocutor started out assuming I would say yes, and before I could answer, she reminded me that most children’s books about echidnas are cloying, saccharine tales of how an anthropomorphic Eddie the echidna couldn’t play with balloons.

Those books aren’t about echidnas, they’re about overcoming disabilities, and while that’s socially useful, those books don’t advance the understanding of science or inspire curiosity about nature. I succumbed to peer pressure and launched into the work, though there would be less of the how-to stuff.

In January this year, the book was well under way, when a new paper in Nature caught my eye (I'm the sort of writer who stays on top of the facts).  This was the Zhou, Yang, Linda Shearwin-Whyatt, Jing Li. et al.  paper on monotreme genomics. Suddenly, the important story was too complex for young readers.

I may yet come back to do a kids' book, but the book I will start pitching to publishers next week is solid history and biology for intelligent adults. Part of the story is about how Europe (mainly London and Paris) learned about echidnas and how they reported them.

Sadly, some of the early reports got the hind foot wrong. The accepted wisdom now is that the monotremes were originally aquatic, more like the platypus, and had a trailing foot, like this dinkus that I sketched for the book.

This Pretre and Massard illustration from 1816 shows the hind feet as they ought to be, though some of the rest is fairly improbable, like the stance and the protruding tongue, which is normally very hard to see. Still, the artists got the feet right!

The next illustration is from the Illustrated Australian News for Home Readers, a sort of newsprint post card to be sent to relatives at Home, which meant Britain to recently arrived Poms.

The art work ought to have been prepared in Australia, and by then we had some excellent home-grown artists, but this was a truly sloppy bit of work.

So where did the error get started? George Shaw got it right in 1792, and when William Bligh (yes, the Bligh of Bounty fame) saw and sketched a freshly-killed one on Bruny Island in Van Diemen's Land.

As you can see from the small version of Bligh's sketch (seem here on the left), he had no trouble with the backwards legs, though that might have been dismissed by some. As a Vandemonian echidna, it would have been less spiny than the ones I see in Sydney.

Still, Waterhouse's 1846 A Natural History of the Mammalia, got the legs all wrong, so clearly. the word wasn't out there.

When you look at an actual animal, the feet are tucked in underneath, and can be hard to see, but over the past year, I have been gathering the evidence:

That brings me up to June 2021, when we were strolling through Sydney's Royal Botanic Gardens, and came across a giant representation of an echidna. As it happens, I know that there were echidnas in the Domain and Gardens in the 1960s, but I don't think they are there now, so maybe the artist had no live model to work on. As you can see, the foot is on backwards!

I reported this singular factual deficiency, but was told "I don't think we'll bother to change it now". So I'm dobbing them in as anatomical sluggards.

Finally, added in September, here's my best hind foot shot so far, taken 7 September on a new youngster at North Head:

And here's another angle:

There has been a hiatus

 It is 6 to 7 weeks since I posted last, and here is the reason: I have been clearing off the back burner of stalled projects and good ideas.

You see, I'm not getting any younger, but there's stuff on my hard disc that will go to waste if I don't get it out there. All I can say is hooray for Amazon Print On Demand and Amazon Kindle.

Old Grandpa's Book of Practical Poems is clearly a nod to T. S. Eliot in the title, but this is a collection  of 328 pieces of poetry and verse that I think every youngster should at least recognise by the age of 18. The idea came to me when I was reading A. A. Milne to a grandchild, and our discussion threw me back to a time when I was working for an online encyclopaedia, and delivering verse on request to teachers who emailed me.

Being methodical, I checked the text, formatted it correctly, sorted it by author and sorted authors by their dates, and before the operation went pear-shaped, I had more than 600,000 words of poems stored away. It's all stuff to read to kids, or for kids to read, a sort of Dead Poet's' Society to enjoy at home.

That's now all available as an ebook for Kindle, but also as a handsome volume in print, for less than $25.

They Saw the Difference is something completely different. For the past half century, I have been writing essays about how science came about. Many of them were broadcast on ABC Radio National, a few appeared in that online encyclopaedia, and others were first written for this blog, or as part of the more than 60 books  I have had published.

Once again, the print volume comes in at under $25, and for that you get >SQRT(2) * 10^5 words, which is two normal paperbacks worth.

I probably could have got either of these books taken up by a traditional print publisher, but the one I really want to go through the trad route is my next book, which is on echidnas.

You see,  publishers are wary of having two books by the same author on the market at the same time. I play all over the fretwork, and one of my books competes with any other, but there's no talking to the petals.

So not a word to anybody, OK? Normal service will be resumed next week.

Different rocks: the birth of geology

 Around 1670, Nicolaus Steno (1638 – 1686) spelled out a set of basic principles of geology which spread fast: by 1671, there was an English translation available. Here is a modern version that conveys the two laws Steno left for us:

The Law of Superposition: in a sequence of strata, any stratum is younger than the strata on which it rests, and it is older than the strata that rest upon it.

The Law of Original Horizontality: strata are deposited horizontally and then deformed to various attitudes later. That is, undisturbed true bedding planes are nearly horizontal.

Cross bedding Malabar, Sydney,
beds laid down in a sandbank at
a ~30º angle.

(It would seem that Steno never saw cross bedding like that shown on the right.)

When James Hutton found an angular unconformity at Siccar Point in Scotland in 1788, the sloping beds he saw had once been horizontal. This is a place where one set of horizontal sediments had been uplifted, folded and eroded, carved away, before other sediments were laid down over them. Below, you can see Hutton’s unconformity: the upper layer is the famous Devonian Old Red Sandstone, sitting unconformably on Silurian greywacke. The two rock types were different.

Hutton’s Siccar Point Unconformity,
Siccar Point, Berwickshire,
Scotland. [Wikimedia Commons].

An unconformity is a place where there has been a break in time, where the upper rocks fail to conform to the ones below. Seeing this led Hutton to believe that the earth was very old, but on theological grounds, he rejected the idea that a divine Creator would make an earth which would wear out, so he looked for a mechanism of renewal. In his view, the planet was some sort of perpetual motion machine. And so we got the uniformitarian principle, the idea that the forces now operating to change the earth’s surface have always operated in the same way. There were no catastrophes, said Hutton, just slow, steady change.

The result, therefore, of this physical inquiry is, that we find no vestige of beginning, no prospect of an end.
—James Hutton, Theory of the Earth, 200.

So what does an unconformity look like? As part of the work for another book (Mistaken for Granite), I set out to locate points where the bottom of the Sydney Basin (Triassic and Permian rocks) sat unconformably on the underlying older rocks. I know several places where the boundary can be seen. One is at Myrtle Beach, south of Sydney, where you can see the tilted metamorphic rocks below, and more or less horizontal rocks above. The gap is from Permian above to Ordovician below.

To set the scene, Australia is old, and at some time before the Permian, the surface of the land was Ordovician and Devonian rocks that had been heaved up, pushed around and eroded. Then during the Permian, part of the continent sank below the sea, and sediments started to be dumped on the old rocks below. Unlike the old rocks being buried, the Permian rocks still keep their horizontal strata that they were laid down in, and so were the Triassic rocks that later covered the Permian beds.

To geologists, this hand on the rock at Myrtle
Beach spans a gap of about 200 million years.

So how big is the gap? The Ordovician era, according to the geological time scale, was 485 to 444 mya (million years ago), while the Permian was 299 to 251 mya. So if the Ordovician rocks beneath were laid down at the close of business on the last day of the Ordovician, and the Permian rocks were laid down on the first morning of the Permian, the gap is 145 million years. At the other extremes, the gap might be 234 million years: on average, it is probably a gap of some 200 million years.

Budawang Ranges: the top is Permian conglomerate, over Devonian metamorphics, tilting ~20º to the left.

There is also another place inland, in a valley of the Budawang Ranges, where you can reach the absolute bottom of the Sydney basin. The Devonian era was 416 to 359 mya, while the Permian was 299 to 251 mya. So if the Devonian rocks beneath were laid down on the last day of the Devonian, and the Permian rocks were laid down on the first morning of the Permian, the gap is 60 million years. If we take the other extremes, the gap might be 165 million years: on average, it was probably a gap in the record of around 100 million years.

In 1785, James Hutton discovered a number of pink veins of granite, pushing their way up into the dark schist above, and this was the first record of dikes. All the igneous rocks form when magma cools: granite cools slowly, deep down and forms large crystals, basalt cools faster near the earth’s surface and has no visible crystals. Dikes arise when molten rock pushes up into cracks in the rocks above, and that is contrary to the idea that rocks are laid down in horizontal layers. Charles Lyell made much of this.

Dyke near Mt Etna, from Charles Lyell’s
Principles of Geology (1834), volume 3.

Suddenly, about 200 years ago, the world of rock-hounds was hit by a flood of apparent contradictions, observations that demanded a wholesale rethink. Just like climate change, new ideas were suddenly there—though was climate change really such a surprise?

We'll come to that next time, but rest assured, scientists are very good at spotting differences!

Different lines: the spectroscope

 

This is what undergraduates
understood by spectroscope,
even in the 1960s.

In 1802, an English chemist named Wollaston noticed a number of black lines in the spectrum of the Sun. Joseph von Fraunhofer (1787 – 1826) saw the same lines in 1814 and mapped them in more detail. He found 570 lines, and named them, according to their prominence. These days, better instruments can detect thousands of Fraunhofer lines across the solar spectrum, and Fraunhofer’s D line can now be distinguished as three separate lines. The new and improved instruments are now usually called spectrographs or spectrometers, but they are still used to dissect and examine spectra. Newton would have given his eye teeth to access one of them.

Fraunhofer’s newly-discovered lines were regarded as gaps in the spectrum, but each line represented a subtraction from a continuous spectrum, the removal of a key wavelength. This mystery stood for more than 40 years before Kirchhoff and Bunsen sorted it when Kirchhoff saw a similarity: some of the ‘dark’ lines in the solar spectrum matched ‘bright’ lines of emission spectra.

Fraunhofer lines, wikimedia
curid=7003857

The terms ‘dark’ and ‘bright’ are relative: in actual fact, the dark lines are only dark in contrast to the rest of the spectrum, and may even be brighter in absolute terms than the visible lines of an emission spectrum. What happened next is best described in Kirchhoff’s own words:

While engaged in a research carried out by Bunsen and myself in common on the spectra of coloured flames, by which it became possible to recognise the qualitative composition of complicated mixtures from the appearance of their spectra in the flame of the blow pipe, I made some observations which give an unexpected explanation of the origin of the Fraunhofer lines and allow us to draw conclusions from them about the composition of the sun’s atmosphere and perhaps also that of the brighter fixed stars.

These lines were hard to see. In his Decline of Science in England (1830), Charles Babbage referred to the problems encountered by an untrained observer. The ‘Mr Herschel’ in the story was William Herschel’s son, who later became Sir John Herschel, a good friend of Babbage, who named one of his sons Herschel Babbage, who was later a minor explorer in Australia.

Conversing with Mr. Herschel on the dark lines seen in the solar spectrum by Fraunhofer, he inquired whether I had seen them; and on my replying in the negative, and expressing a great desire to see them, he mentioned the extreme difficulty he had had, even with Fraunhofer’s description in his hand and the long time which it had cost him in detecting them. My friend then added, “I will prepare the apparatus, and put you in such a position that they shall be visible, and yet you shall look for them and not find them: after which, while you remain in the same position, I will instruct you how to see them, and you shall see them, and not merely wonder you did not see them before, but you shall find it impossible to look at the spectrum without seeing them.”

Over time, the instruments improved, and by 1864, William Huggins took the spectrum of a nebula. Before long, Doppler shifts (get the book!) were being measured on photographs of spectra, and we were on the way to the notions of expanding universes, Big Bangs and much more.

William Ramsay studied chemistry in Germany under Robert Bunsen, and in 1894, tackled a problem Lord Rayleigh had found with nitrogen. When nitrogen is made chemically, it has one density, when it is prepared by subtracting the other known gases from an air sample, it is slightly more dense. Ramsay remembered that Henry Cavendish had seen the same problem a century earlier, when he tried to combine all of the nitrogen in air with oxygen, but found there was always a bubble of gas left over. Ramsay heated gas with magnesium to make magnesium nitride, but still found a bubble of gas left behind, which was more dense than nitrogen.

Ramsay and Rayleigh had access to the spectroscope that Bunsen and Kirchhoff had introduced, and this revealed a spectrum which fitted no known element. They named the element ‘argon’, meaning ‘inert’. But, they reasoned, if there was one new element to fit into the periodic table (chapter 6), there should be more, one for each row of the table. Ramsay began the search, and looked at a sample of gas from a uranium mineral, cleveite, and found that the spectrum was that of a ‘metallic element’ previously discovered in the sun’s spectrum by Norman Lockyer, who had named it helium.

But what were the lines? The best way to answer this is to first go sideways for a bit. Glass is mainly sodium silicate, and no chemist who has ever heated glass in the flame of a Bunsen burner would doubt the sodium part. Like common salt, glass gives what looks like a distinctive yellow colour to the flame. We know now that there are actually two colours, with wavelengths of 589.592 and 588.995 nanometres, but for now, we can treat them as a single colour.

Fraunhofer’s newly-discovered lines represented a subtraction from a continuous spectrum, the removal of a key wavelength. If you view light that had passed through a medium rich in sodium, the ‘sodium colours’ are absorbed, leaving a ‘line’. As we understand it today, sodium ions in the flame absorb energy of that wavelength. The energy shifts an electron from a lower-energy orbital to a higher-energy orbital, and according to some ideas that we will look at later, that quantum, that very precise packet of energy, the difference between the two orbitals, is associated with a particular wavelength and colour.

If light passes through a cloud of sodium ions, light of that frequency will be extracted and used to ‘excite’ electrons. Later, the electrons drop back down to a lower energy level, and emit light of exactly the same frequency, but most of it goes sideways, so we miss seeing it in the light coming our way. Kirchhoff then described other similar experiments in which flames ‘doped’ with either sodium or lithium act as either absorbers or emitters on limelight and sunlight.

I conclude from these observations that a coloured flame in whose spectrum bright sharp lines appear so weakens rays of the colour of these lines, if they pass through it, that dark lines appear in place of the bright ones, whenever a source of light of sufficient intensity, in whose spectrum these lines are otherwise absent, is brought behind the flame.
— Monatsberichte der Akademie der Wissenschaft zu Berlin, October 1859.

Later, Anders Ångström would use spectroscopy to show there was hydrogen in the sun, Johann Balmer would explain the lines, and Norman Lockyer would find helium there as well, while William Crookes detected thallium without ever seeing it, by finding a green line in a spectrum from some residues in a sulfuric acid factory.

Jean Foucault, the inventor of Foucault’s pendulum (chapter 13 in the book), first discovered the way the emission and absorption effects are linked, but he failed to follow this through to a logical conclusion. Instead, it was left to Bunsen and Kirchhoff to reveal this discovery. And of course Bunsen and Kirchhoff used the heat of the Bunsen burner for their observations, but there was more to come, as readers of my book can see in chapter 10.

It cannot therefore be doubted that the extensive volcanic elevations constituting the high table-land of Armenia and the island Iceland have flowed from sources which were chemically identical… the mineralogical differences between those Caucasian and Icelandic rocks which present the same mean composition, are not less marked than those observed among other ferruginous rocks of plutonic origin.
— Robert Wilhelm Bunsen, Poggendorff’s Annalen, 1851, Scientific Memoirs, edited by Tyndall and Francis, 1853.

Now that was a difference!

Different light: Newton and the spectrum

This is the next sample from They Saw the Difference.

When I was three, my bedroom had the leadlight windows that were popular as a bit of middle-class poshness in the 1930s, when our house was built. These windows were made of small pieces of glass, held together between H-shaped strips of lead. Each window had one special piece of extra clear glass with bevelled edges, and these gave me one of the wonders of my youth.

The windows faced west, and at certain times of the year, when the low afternoon sun shone between the houses across the road, it hit these angled pieces of glass, and a small coloured patch appeared on my wall—my own private rainbow, captive in my room. 

Any triangular piece of glass will bend light, and the light is split because each of the colours is refracted by a different amount, because each colour has a different wavelength. If we want to see the effect well, it is best to use a narrow beam of white light, and pass it through a prism in a darkened room. Newton saw it, and wondered why the light was different.

A prism is just a solid figure that is essentially triangular in shape and made of a transparent material. Prisms are commonly used in physics to deviate or disperse a ray in optical instruments or laboratory experiments, or to deliver total internal reflection. Here is how Newton set up his investigation:

 

In this diagram, white light comes
from the right and is dispersed.

One thing is certain, this three-year-old was too late to make any original discoveries, because Newton completed his systematic study of the spectrum, long before I was born. In 1666 he saw the composite nature of white light while carrying trying to minimise chromatic dispersion in lenses, an annoying effect that had been known for about fifty years, when telescopes and microscopes gave images with coloured fringes. 

In 1672, Newton told the world how he had studied the ‘celebrated phenomenon of colours’. At the time, most people assumed that colour was a mix of light and dark, that the prism somehow added the colour. and Robert Hooke was one of the strongest supporters of this view.

With two neat experiments, Newton demolished Hooke’s ideas, and began one of the great feuds of science. (In case you don’t know it yet, science is driven by spotting differences, but there’s always room for personal differences, and many of the wildest brawls revolved around Newton. By comparison, Dart’s clashes with the Piltdown gang {see the last blog} were nothing!) 

In one experiment, Newton used a second prism to pull the colours back together again, and showed that the result was white light. Then he used a second prism and a slit to show that when a selected band of coloured light passed into the second prism, it passed on unchanged. Hooke’s theory was in tatters, and Newton had an enemy for life. Newton wrote no more on optics until after Hooke died in 1703. 

 In fairness to a rather peculiar man, Newton simply could not help bursting out with the truth, even if it got up people’s noses! Novelist Aldous Huxley assessed Newton this way: 

If we evolved a race of Isaac Newtons, that would not be progress. For the price Newton had to pay for being a supreme intellect was that he was incapable of friendship, love, fatherhood, and many other desirable things. As a man he was a failure; as a monster he was superb.

How Newton’s experiment
is often wrongly shown.

Newton’s experiment is often shown like this, upside down, with a triangular prism sitting on its base, the light coming from below, bending down as it passes through the apex and being directed further down on the other side. Newton used sunlight shining down (not up!) through gap in a window, and being bent through the apex of an upside-down prism to shine upwards onto a wall, 22 feet (7 metres) away. 

We know the sitting-on-its-base-prism picture is wrong, because of the angle of the incoming beam, and besides, the band at the top is ultraviolet (above violet), while that at the bottom is infrared, meaning below red. The prism had to be point-down. The room must have been darkened, with just one beam of light entering the room and throwing a pale spectrum onto the wall, red at the bottom, violet at the top. 

Newton called the colours ‘spectrum’, a Latin word meaning spectre or apparition, and he is said to have been the first to see a prism, but I wonder how many others had found their own private rainbows before him, given that he spoke of the ‘celebrated phenomenon of colours’. 

Those celebrated colours were just those of the rainbow, but how many were there? Almost everybody had their own version. In fact the spectrum contains an infinite number of colours, and the number we ‘see’ is subjective. Newton followed a Greek astronomer named Ptolemy who had said there were seven colours, and gave them the names we use today: red, orange, yellow, green, blue, indigo and violet. 

 He said he could not separate any further colours from any narrow band of light selected from the spectrum, but his set-up would never have given monochromatic light in any selected band, because the rays from the Sun are not completely parallel. He should have seen further separation, but perhaps he intended his ‘result’ to be taken only as an idealised case. Or maybe he fudged his experiment: he stated correctly that different colours are refracted (bent) through different angles, both in prisms and in lenses, and that was the important part. 

What we now call visible light is just a small part of a much larger electromagnetic spectrum, but as we will see in chapter 5, this took time to find, and it is important to note that this is just the range that we humans see. There are many insects, bees for example, which are different because they can see ultraviolet light. 

So how do you see something that cannot be seen? In 1799, an astronomer named Sir William Herschel was measuring the temperatures associated with different colours. He had been using filters to view the Sun, but he saw how some filters that he used when examining sunspots let more heat through.

This led him to wonder if different colours had different amounts of heat, and he used thermometers to measure the strength of heating along a normal spectrum. He did this because his observations made him speculate that: 

 …the prismatic rays might have the power of heating bodies very unequally distributed among them…If certain colours should be more apt to occasion heat, others might, on the contrary, be more fit for vision by possessing superior illuminating power. 

Herschel found a higher temperature near the red end, and testing just beyond the visible range, found an even higher temperature, so he named this radiation ‘calorific rays’. He showed that these invisible rays behaved like visible light, being reflected, refracted and transmitted, the same tests Heinrich Hertz later applied to his radio waves. 

Herschel delivered a number of papers on the subject to the Royal Society in 1800, describing several hundred experiments on what he called “invisible light”, and since then, infrared astronomy has increased in importance as more sensitive instruments to detect infrared radiation have been developed. We will look more at infrared and infrared astronomy in the book. 

Johann Ritter tested the ultraviolet end of the spectrum, using silver chloride to detect radiation beyond violet. Photographers would later use the way light makes silver chloride go black, but Ritter found that there was an invisible band of radiation, even better than white light at blackening the silver chloride, which we now call UV. 

To sum up, the visible part of the electromagnetic spectrum, ranging in wavelength from approximately 3.9×10-7m (violet) to 7.8×10-7m (red) (corresponding frequencies 7.7×1014 Hz and 3.8×1014 Hz, respectively). 

As Aldous Huxley reminded us, Newton was unpleasant. He mistreated Stephen Gray, he quarrelled with Robert Hooke over the inverse square law and his theory of colour, with Gottfried Leibniz over the invention of calculus, and with Christiaan Huygens over his theory of light. 

Even so, any one of Newton’s achievements would have been enough to ensure his fame, even without the apple. But did the apple really fall? We will never know now, but the tale was made popular by Voltaire, and Newton’s biographer and friend, William Stukeley, claimed Newton told him the story, so maybe there was a day when the apple fell, and made Newton wonder why it should be so. That is Newton’s greatest gift to us, that he asked why as often as he did, even inspiring poets like Paul Valéry and Alexander Pope, who wrote: 

Nature and Nature’s laws lay hid in night:

God said ‘Let Newton be.’ and all was light. 

Mind you, Sir John Collings Squire would later add:

It did not last: the Devil shouting ‘Ho, 

Let Einstein be.’ restored the status quo. 

Newton told Hooke that if he had seen further than others, it was because he had stood on the shoulders of giants. This may have been a snide dig at Hooke, but a similar remark had been made by many others, centuries earlier. Robert Merton has even written a whole delightful book (On the Shoulders of Giants), on the subject, tracing the earlier history of the aphorism.

It was once cited with this brilliant typo: 

Merton, Robert K., On the Shoulders of Grants: A Shandean Postscript, Harcourt Brace, New York, 1965. 

—Max Charlesworth, Lyndsay Farrall, Terry Stokes, David Turnbull, Life Among the Scientists, Oxford University Press, 1989, bibliography, 295.

Next, we'll look at the spectroscope and what it can do.

A Different Brain

 This is the first part of They Saw The Difference, announced here.

Dart’s original illustration of
the Taung child, 1925.

I have always told my students that the best actors go into law, the next best become teachers, and the leftovers go to stage and screen. The reader may justly conclude from this that when I teach (or write) I’m putting on a show.

About 1992, I prepared for work each day by slipping the fossilised toe-bone of a giant kangaroo into my shirt pocket, a child’s brain into one trouser pocket and its skull into the other.

<SFX> Brakes screech, voices off, shouting “Wha-a-at?”

To clarify, the skull and brain were fossils, 2 to 3 million years old, plus or minus a bit, and if the kangaroo toe-bone was real, museums around the world make casts of their best and rarest examples to sell to other museums, so what you see in a glass case or a lecturer’s hand is usually a copy, cast in resin from a mould of the original, and painted to resemble the original, which is somewhere safe. No matter, just having casts of the skull and part of its brain in my pockets allowed me to tell their story, as well as if I held the genuine relics.

Raymond Dart was an Australian teaching in South Africa in the 1920s. In 1924, he received two boxes of rocks on a morning when he was supposed to be getting ready to act as best man to his friend, Christo Beyers. Peeking into one of the boxes, he saw the cast of a brain lying loose, and in that, he saw something important.

Soon after the brain’s owner died, mud partly filled a skull, and this mud later hardened to rock. Technically, it was an endocast, a copy of part of the inside of the skull which closely reflected the brain, but it wasn’t any old brain—it was special, because of its small size and the position of its brain stem.

Interpreting fossils is an art and a science. Experts must know anatomy, how the parts work together, what small differences mean, and they work with those small differences. The position of the large hole in the skull where the spinal cord leaves the brain, the foramen magnum, was immediately obvious in the shape of the brain. Any animal with a brain stem like that had to have walked upright.

We cannot be certain how the Taung child died, but clearly the skull had ended up on its side in a lime-rich deposit, where the brain case was slightly more than half-filled with the mud which became the cast.

Dart saw that it fitted into a block of stone in the case, so a major part of the brain owner’s skull was probably there as well. He was a medical man, but fascinated by fossils, and he knew that this was important.  So was his friend's wedding, but afterwards, he itched to get back to his find.

The covering rock had to be carefully removed before the face could be examined, but a quick look at the cast was all Dart needed. The brain said this animal had a skull which attached to a vertical spine, lying directly below the skull, rather than behind it, as in chimpanzees and gorillas. The owner walked upright, like modern humans. Here is how Dart worked it out:

I was also convinced from the earliest period of my investigations that these creatures had placed great reliance on their feet for walking and running and that, consequently, their hands must have been freed for other tasks. This was implicit in the globular form of the skull which was obviously balanced on a more vertically placed type of backbone than that of a gorilla or chimpanzee. The improvement in the poise of the head implied a better posture of the whole body framework, since there must have been a relative forward displacement of the foramen magnum (the hole in the base of the skull which links the brain with the spinal cord).
—Raymond Dart, Adventures with the Missing Link, 1959, 11.

The people who interpret fossils work like Sherlock Holmes at his best. To those who can read, a glimpse of a document can be enough, but those who can read fossils can gain just as much from a single glimpse of just the right hint. At this point, Dart made a political mistake.

Even in the 1920s, a careful observer would have seen that the British Empire was already in decay, and there were few careful observers around, but there was a cast-iron rule: London is always right. When Dart reported his find in Nature in 1925, London came down on him like a ton of bricks.

His find (known as the “Taung child”, from where it was found and its obvious youthfulness) was small-brained and most British scientists were certain that any small-brained thing was no ancestor of theirs. Piltdown Man was the human beginning, they said: he had a big brain, and best of all, he was found in Britain! (There’s more on Piltdown in the Afterword, but you'll have to get the book to read that.)

Today, we might think Dart’s name for his find, Australopithecus (“southern ape”), was not the best name for an upright-walking individual, even one with a small brain, but Dart was trying not to draw too much fire upon himself. It didn’t work, but in the long run, the brain stem evidence held up and Piltdown was eventually shown to be a fake.

The true status of the Taung child lay hidden inside its jaw until 1987. In both humans and the other apes, the “adult” teeth emerge in a specific sequence. There is one order of appearance in humans, and a different order of tooth eruption in the other apes. Concealed inside the Taung child’s skull, teeth were erupting, and their pattern of development would tell us what the Taung child was, either human or ape. As there is only one Taung child, you cannot slice it up, just to see what is inside. You could take X-rays, but there is too much other material in the way, and the things we are looking for are much too faint.

For many years, it seemed as though we would never know what was inside the jaw. Then in 1987, Glenn Conroy and Michael Vannier had a bright idea. Instead of cutting the skull into thin slices, they made a series of virtual slices with X-rays, and fed the results into a computer, and used back projection to build up a three-dimensional picture of what was inside. Seeing how the Taung baby’s teeth were erupting would give the answer.

The researchers took their X-ray shots, just 2 mm apart, in three different dimensions: vertically, from front to back, vertically, from side to side, and horizontally. (They called it the sagittal, coronal and transaxial planes, if you prefer the technicalities.) The method is less important, but the answer was delightful:

…the Taung ‘child’ is not a little human, but just as important, it is not a little ape…
— Glenn C. Conroy & Michael W. Vannier, Nature 329, 625–627, 21 October 1987.

The whole answer was told in the differences: the Taung baby is a betwixt-and-between, a half-and-half, a missing link if you wish, and we would never have known if the two researchers had not decided to give it a CAT scan! Sadly, we had to wait another sixty years to find out what it was.

The story I told, over several years at the Australian Museum, was about how Dart saw a difference, and recognised a new scientific truth. This was just a few years after Conroy and Vannier had confirmed the role the Taung child’s people played in our origins, but there was more: I had human and gorilla skulls, that toe bone of the giant kangaroo and the matching bone from a horse. Always, it was about differences.

At other times, I talked to my audience about Edward Tyson (1651 – 1708), one of the unsung heroes of science, who persuaded Robert Hooke to pay seven shillings and sixpence for a 43 kg porpoise from a London fishmonger, so Tyson could dissect it. Back then, even experts like John Ray called the porpoise a fish, but Tyson’s Anatomy of a Porpess, published in 1680 showed the danger of judging a book by its cover. He said: “If we view a Porpess on the outside, there is nothing more than a Fish, but if we look within, there is nothing less.”

Tyson later dissected an infant chimpanzee which had died after being brought to London from Angola. While he referred to it as both a ‘pygmie’ and an ‘Orang-Outang’, the drawings show a chimpanzee, but Tyson’s book, filled with illustrations, showed for the first time just how close humans were to the other animals, and how they differed.

If Copernicus had removed the earth from the centre of the universe (something I describe in chapter 10), Tyson and his assistant, William Cowper, helped to remove Homo sapiens from a central position in creation. This change tied together humans and the whole of ‘lower’ creation. Tyson had taken one of the crucial steps towards recognising that evolution happened.

Next, back to Newton again…

They saw the difference

 I am, first and foremost, an historian of science, and I'm going to talk for the next month or so about my new e-book, soon to be a print-on-demand book, called They Saw the Difference. The thing is, I've been busy getting our block of townhouses repainted and rejigging a couple of older titles. so for now, here's the introduction to They Saw the Difference.

I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When,
And How and Where and Who.
—Rudyard Kipling, introduction to ‘The Elephant’s Child’ in the Just So Stories.

Differences, seeking, cultivating and studying them, make our civilisation work. The art of noting and celebrating differences bloomed in Renaissance Europe, and detecting differences shaped modern science and technology, but the habit was there long ago.

The early hominin who saw that this rock was better than that rock for forming tools, or observed that wood burned and rocks did not, the one who noticed that water ran downhill and not up, these were the ancestors of modern scientists and technologists.

My granddaughters
seeing the difference
an echidna makes.

As the subtitle says, this is a social history of science, concentrating on the why and the how, with a good dollop of what, and something of the who, where and when, along with regular bursts of something completely different. This book compulsively pursues puzzles to their ends.

For example engineers and physicists, hunting for scraps of literary icing to decorate their published work often quote these words of Paul Ambroise Valéry (1871 – 1945): “One had to be a Newton to notice that the moon is falling, when everyone sees that it doesn’t fall.”

If the quoters offer a source (most of them don't), it has a date of 1970, which is well after the poet’s death. By enlisting the burrowing skills of Project Wombat, I know that their 1970 source is volume 14 of Valéry’s posthumous collected works, but the quote was first published as “Il fallait être Newton pour apercevoir que la lune tombe, quand tout le monde voit bien qu’elle ne tombe pas,” in Mélange, Grandeurs, 384, Oeuvres, t. 1, La Pléiade, in 1939. I sweat the details to get the backstory.

“Is there any point to which you would wish to draw my attention?”
“To the curious incident of the dog in the night-time.”
“The dog did nothing in the night-time.”
“That was the curious incident,” remarked Sherlock Holmes.
—Arthur Conan Doyle, ‘Silver Blaze’, in The Memoirs of Sherlock Holmes.

Valéry knew what was going down when Newton’s apple fell. He didn’t imagine crazy young Isaac, sitting under a tree, thinking “apple, falling: that’s odd!”. Newton was differently equipped, mentally speaking, but he knew his apples. To him, the odd thing wasn’t the falling apple, it was the curious way the moon failed ever to reach Earth. That was his dog that didn’t bark in the night.

He saw that the moon’s orbit involved a fall that went on forever (in our time frame), the descent always cancelled out by the satellite’s forward motion. That was the difference he saw, a whole branch of science sprang from it, and Paul Valéry could see that. We will return to Isaac Newton again soon, because he could see differences, and he also made a difference.

I chose to follow, not the broad highways of science, thronged by the famous and important, but rather to stray down the alleys and dusty tracks, where the interesting people and the curious science lie in wait for us. I have enjoyed making this work, written for the child I once was and still am: I hope you find some of the same joy.

Two roads diverged in a wood, and I—
I took the one less traveled by,
And that has made all the difference.
— Robert Frost, The Road Not Taken.

Back in the saddle

 Well, the past three months have been a bit of a rush. I finished editing and compiling Old Grandpa's Book of Practical Poems, mainly for my grandchildren, and that was going to be it, but there was an old ms, lingering on my hard disc, a novel with the working title Sheep May Safely Craze. That is now (as of this morning) locked up and being submitted.

No sooner had I got into the sheep than I attended a kid's lit function, and before I go on, I need to comment. An over-rated novelist once said in a radio interview that he might write for children, “but only if I had brain damage”. This got right up the noses of children’s writers everywhere, because those of us who write for the young know that our craft is far more challenging than writing for adults.

True, the occasional B-grade royal or C-grade celebrity may “write a book for children” (usually meaning they had it ghost-written), but the sales of “their” fulsome drivel will usually relate only to the alleged author’s notoriety.

Such works are stereotyped, devoid of intellectual commitment or literary value. No matter, we serious and devoted scriveners keep on engaging young minds, turning on the lights, although I sometimes take a break and write a book for adult readers, if there’s a story there that will feed older minds. The book I describe below is just such a case.

The trapped echidna

Still, I am best known as a writer of non-fiction for children, and it was in that role that I spoke last December at a kids’ lit function, where I described the adventutes I had while rescuing an echidna from a locked drain (the details are set out in chapter 12, but briefly, it involved kneeling on a steel grille, handling a heavy echidna that was grimly gripping a steel ladder, putting me at risk of toppling head-first into a water-filled sump).

The freed echidna

Over coffee afterwards, three friends asked me, separately, and within the space of a couple of minutes, if I was doing a book on echidnas. My answers were, respectively, “Naaah”, “Maybe” and “You betcha!”

My third interlocutor started out by assuming I would say yes, and before I could answer, she had reminded me that most children’s books about echidnas are cloying, saccharine tales of how an anthropomorphic Eddie the echidna couldn’t play with balloons. Those books aren’t about echidnas, they’re about overcoming disabilities, and while that’s socially useful, those books don’t advance understanding or inspire curiosity.

I had already decided that editing a poetry anthology for youngsters and completing a social history of science for oldsters would see me ready to hang up my pen and retire to gardening, leavened by watching noisy action movies and reading Proust, Joyce, P. D. James, Andrea Camilleri and other quality murder mysteries. Instead, I succumbed to peer pressure and launched into this

(Literary social climbers will be pleased to know that Proust and Joyce return in cameo roles in chapter 10, though this may be seen as a cunning ploy to convert certain library costs into tax deductions.)

Going home on the ferry, I started making notes, and I soon realised I would have to read a lot of technical stuff, but there was a story there, waiting to be told, and young readers would like it. Echidnas, spiny anteaters, porcupine anteaters (or Tachyglossus aculeatus if you have my sort of training), have odd quirks. My notes, my initial thoughts, included the following headings, all later went into my planning spreadsheet, and here they are:

* spiky, not at all cuddly;
* not really warm, lay eggs, suckle young:
* many scientific names;
* mainly solitary;
* good diggers (claws!);
* fossils, platypus relatives, Zaglossus;
* Sydney 2000 Olympic mascots: echidna, platypus and kookaburra;
* five-cent coin, postage stamp:
* echidna trains;
* do they drink water?

Over the next fortnight, my plan began to change, because in one week, Christine and I saw four different echidnas, and in the five days around Christmas 2020, we saw three more, and different, echidnas. Then when I started looking at the scientific literature, I realised the really good story was too complex for young readers.

My initial plan for an intellectually honest, stereotype-free, factual book for youngsters had to go on hold. Having declared to friends and family that echidnas (working title) is to be my Last Book, I may still come back to do a simpler version for youngsters, because we still don’t have all the answers, and that’s a good thing for young people (of all ages) to know.

In this book, you will find heaps of technical stuff about physiology, chromosomes, parasites, embryos, membranes, teeth and more. I promise one thing, though: as a children’s writer, I take all the facts, one at a time, and make each give a sound account of itself, but there will only be facts. There will be no flights of fantasy like one I found in Blazing Passion, the book a friend from Project Wombat passed on, complete with this blurb:

…a breathtaking romance that races from the turbulence of nineteenth-century England to the sweltering penal colonies in the Australian jungle…

The book in question was published by Playboy Books, and ‘Stephanie Blake’ is in reality two men who clearly know very little about Australia (“sweltering penal colonies in the Australian jungle”?), but, one assumes, given their publisher, know lots about erotic fantasy. Should you want a copy, Blazing Passion came out in 1978. To save your time, here’s a sample of what passes for dialogue there:

“I’ll fix you up a proper feast. Platypus eggs. Bacon. Sausage and pancakes. And real coffee …”

Actually, I do offer one flight of fantasy later on in the book, but it is clearly fanciful. Finding it is something I leave to the reader, but it’s not the bit about socks full of sea urchins. Those are totally real, and also rate a mention in Sheep.

But that's another story.

Actually, what is a whole 'nother story is that I am resuming control of my out-of-print works and republishing under the Amazon Print-on-demand system.

More on that, later...