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Thursday, 14 December 2017

Bushfire backgrounder

Bushfires are a part of high summer in Australia. In winter each year, Australians carry out control burns, small fires aimed at reducing the amount of standing fuel. These may help to contain the fires or stop them, but given the wrong weather, no amount of control burning can stop fires happening somewhere. The science is against any other outcome.

A note first about terms: in Australian English, ‘bush’ is what others might call forest, heath or scrub. The term was brought to Australia by early settlers who had previously lived and worked in North America, so this quintessentially Australian term is in fact an early American import! A ‘bushfire’ is a fire running wild in the bush. 

Many botanists in the past have been forced to change their research to ‘bushfire regeneration’ after their plots were burned out, and the cost of fires has meant that there has been a great deal of research on the topic.

First, let us consider the biology of bushfire in Australia. Fire is a natural part of the bush cycle, so the natural environment should survive fairly well, just so long as there is no heavy rain, too soon afterwards. That is why the fire fighters will concentrate on saving property and lives.

They will fight fire with fire, knowing that what they burn deliberately will grow back again, refreshed by the flames. Australia’s bush, after all, lived with fire for many millions of years, long before humans came here. The bush will grow back after the fires have done their worst.

Next, let us consider the geology and geography of urban Sydney bushfires. When the first Europeans reached Australia in 1788, they settled in what is now Sydney, either on flat land near the sea or on the ridges.

Sydney sits on a bed of sandstone, two to three hundred metres thick, with joints running north-south and east-west. It was laid down in a Triassic delta, rather like Bangladesh today, with a huge river braiding back and forth, washing out the finest minerals, the clay and other mineral-rich sediments, and leaving just the quartz grains behind. The grains were rounded, and had probably been in an earlier sandstone somewhere else, but they settled where Sydney is now, almost 200 million years ago, waiting to play their part in shaping modern Sydney.

Some of the sandstone beds are better bonded than the others within this ‘Hawkesbury sandstone’, but they are otherwise pretty much the same, right through the deposit. (Hawkesbury, in case you are wondering, was a minor 18th century English politician who had a local river named after him. The stone was later named after the river.)

In the last Ice Age, the sea level around Australia was much lower, due to all the water tied up in the northern glaciers. Then, today’s Sydney Harbour was a river valley, shaped by the jointing pattern in the sandstone. Joints, planes of weakness in the stone, were eroded into crevices which became valleys, with the more resistant sandstone forming ridges. Later, the sea level rose, creating a ‘drowned river valley’ with a characteristic fern leaf shape, the modern Sydney Harbour. A few of the higher ridges have a shale capping which offered rather better soil than the sand which derives from sandstone.

The first whites settled on the coast, then headed (a) for the flat land of the ridges, where roads were easier to build, and (b) for the richer soil on the shale-capped ridges. First, they built small farms and market gardens, then roads were built to service these, and soon the residences followed, as a young city grew. Down in the valleys, close to the sea, the bush was left alone. It was too hard to build roads down to there, and so people left it alone. Even today, much of the valley bush is preserved, with homes sitting on the ridges above: a sure recipe for trouble, because heat and flames rise.

Fuel builds up in the bush over a period of years. Gum trees shed their bark, branches and leaves, smaller shrubs in the under-storey die and are replaced by others, and after a few years of recovery, the lowest three metres or so is a closely packed mass of dead and drying twigs. Until they break and fall, these pieces of finely divided wood rot very little in the dry bush, and even on the forest floor, rotting is a slow business, for the sandy soil drains fast after rain. Heath regenerates fast.

Some of them can be ready to burn again, just six months after a major fire. Other areas can take ten to twenty years to be ready for a major burn. As a general rule, after 40 or 50 years, any area at all will be ready to sustain a ‘blow-up fire’.

Now for the physics of bushfires in Australia. When any fire starts, it begins very slowly. It takes time to develop from a maker of smoky wisps into a maker of misery. The dangerous fire is one that roars and gusts through the tree tops, the crowns of the trees, a firestorm traveling at 50 kilometres an hour or more, leaping ahead of itself, and destroying all in its path.

Crowning fires can cross 400 metres of open water, as the sparks and burning rubbish fly up in the roaring flames, and then tumble down on the other side. Any footage you see on your local TV will be of these crowning wildfires.

You will see flames gouting 30 metres or more into the air, searing the upper branches of gum trees, leaping across the fire breaks, and almost impossible to control until the weather improves.

Now let us look at the question of weather and bushfires. The weather is the last factor in the bushfire equation. At the moment, we have hot dry nor-westers, gusting at up to 50 knots, pushing the fires downhill as well as up. Usually, a fire front can be beaten as it crests a ridge.

Fires go fast uphill and slow downhill, but they do run downhill. On the forward side of any advancing fire, you will find a wind blowing towards the flames at the front of the fire. If you can set small fires on the far side of a ridge, they will gather strength and rush up, sucked in by the fire wind from the blaze on the other side, until the small fires meet the major fire coming the other way.

In this style of fire-fighting, the major fire limps over the ridge, only to find that most of the fuel in its path has already been burned. Starved, it falters like a wounded beast, and puny men and women rush in to attack it with sprays and hoses. But with high winds, this ploy is too dangerous to attempt, as the fire lighters in its path could easily be over-run, as it leaps over the fire break they have just made.

Within hours of the fire, the seeds will be dropping from the woody fruits of the she-oaks, Hakeas and Banksias, and the trunks and underground stems of other plants will already be starting to shoot. In three weeks, there will be green all over the bush. In time, the bush will recover, and so will the animals. The homes can be rebuilt, and lives, so long as they have not been lost, will go on. It is all part of the natural cycle. The animals will take longer, but some will survive, and others will move in from unburnt areas, but recovery is a slow natural cycle.

Thursday, 30 November 2017

Australian Backyard Earth Scientist

I have just published my peculiar novel, Sheep May Safely Craze on Kindle. This is a comic romp through history, literature, higher mathematics, lower mathematics, logic, mythology, cosmology and the dark side of pea soup, and it is available on Kindle. You can read more about it here. 

Anyhow, I have now turned back to earth science for younger readers again, as the editor's responses come my way from the Number One editor at the National Library of Australia, Jo Karmel. This is the fifth book we have worked on together (or seventh, if you count new editions separately), and there's another on the way

Anyhow, by the time we are finished, Australian Backyard Earth Scientist is going to be a good book, but here are some left-overs, more suited to older readers. These might have been epigraphs, but we don't do those for younger readers. Here are the unused quotes, and a few pics from my short-list (~250 shots at last count).

Earth science

Folds, Mt Pilatus, Switzerland.
A rolling stone gathers no moss.
— Proverb, dating back to the 16th century.

To a naturalist nothing is indifferent; the humble moss that creeps upon the stone is equally interesting as the lofty pine which so beautifully adorns the valley or the mountain: but to a naturalist who is reading in the face of the rocks the annals of a former world, the mossy covering which obstructs his view, and renders indistinguishable the different species of stone, is no less than a serious subject of regret.
― James Hutton, Theory of the Earth, vol. 3, 46.

A rock or stone is not a subject that, of itself, may interest a philosopher to study; but, when he comes to see the necessity of those hard bodies, in the constitution of this earth, or for the permanency of the land on which we dwell, and when he finds that there are means wisely provided for the renovation of this necessary decaying part, as well as that of every other, he then, with pleasure, contemplates this manifestation of design, and thus connects the mineral system of this earth with that by which the heavenly bodies are made to move perpetually in their orbits.
— James Hutton. Theory of the Earth, with Proofs and l1lustrations, Vol. 1 (1795), 276.

An historian should, if possible, be at once profoundly acquainted with ethics, politics, jurisprudence, the military art, theology; in a word, with all branches of knowledge … It would be no less desirable that a geologist should be well versed in chemistry, natural philosophy, mineralogy, zoology, comparative anatomy, botany; in short, in every science relating to organic and inorganic nature.
— Sir Charles Lyell, Principles of Geology, Vol. 1, 3, 1835.

…the successive series of stratified formations are piled on one another, almost like courses of masonry.
— William Buckland, Geology and Mineralogy, Considered with Reference to Natural Theology, Bridgewater Treatise 6, Vol. 1, 37, 1836.

Folds and faults, S. coast NSW.
[When] spring and summer come round, how easily may the hammer be buckled round the waist, and the student emerge from the dust of town into the joyous air of the country, for a few delightful hours among the rocks.
— Sir Archibald Geikie, in The Story of a Boulder: or, Gleanings from the Note-book of a Field Geologist (1858), viii.

Apart from its healthful mental training as a branch of ordinary education, geology as an open-air pursuit affords an admirable training in habits of observation, furnishes a delightful relief from the cares and routine of everyday life, takes us into the open fields and the free fresh face of nature, leads us into all manner of sequestered nooks, whither hardly any other occupation or interest would be likely to send us, sets before us problems of the highest interest regarding the history of the ground beneath our feet, and thus gives a new charm to scenery which may be already replete with attractions.
— Sir Archibald Geikie, Outlines of Field-Geology (1900), 251-2.

Experimental geology has this in common with all other branches of our science, petrology and palaeontology included, that in the long run it withers indoors.
— Phillip H. Kuenen’ 'Experiments in Geology', Transactions of the Geological Society of Glasgow (1958), 23, 25.

No Geology without Marine Geology!
— Phillip H. Kuenen, Title of paper, Geologische Rundschau, 47(1), 1958, 1 – 10.

Geology itself is only chemistry with the element of time added.
— Ralph Waldo Emerson, Aspects of Culture, The American and Continental Monthly, Volume 1, April 1870, 5.

Beneath all the wealth of detail in a geological map lies an elegant, orderly simplicity.
— Tuzo Wilson, As quoted G.D. Garland in obituary 'John Tuzo Wilson', Biographical Memoirs of Fellows of the Royal Society (Nov 1995), 552.


Hexagonal packing can turn up unexpectedly.
To understand the very large, we must understand the very small.
— Democritus (470 – 380 BC)

… in the field some amount of information concerning igneous rocks can be obtained by rubbing down the chip on a grindstone and using a whetstone, carborundum file, or water of Ayr stone for the final grinding. By these and other methods … there are obtained slices of rocks which, though thick, uneven, scratched, and all that is bad, from the point of view of the professional maker of thin sections, are nevertheless capable of yielding much information. With a pocket lens it is possible to make out from such a 'thin' section the nature of the minerals present, the texture and the nature of the rock.
— Frank Rutley, Elements of Mineralogy, 22nd edition, 1915, p. 104.

The difference between a piece of stone and an atom is that an atom is highly organised, whereas the stone is not. The atom is a pattern, and the molecule is a pattern, and the crystal is a pattern; but the stone, although it is made up of these patterns, is just a mere confusion. It's only when life appears that you begin to get organisation on a larger scale. Life takes the atoms and molecules and crystals; but, instead of making a mess of them like the stone, it combines them into new and more elaborate patterns of its own.
— Aldous Huxley (1894 – 1963), Time Must Have a Stop. London: Chatto and Windus, 1945, chapter 14.

A crystal lacks rhythm from excess of pattern, while a fog is unrhythmic in that it exhibits a patternless confusion of detail.
— A. N. Whitehead (1861 – 1947), An Introduction to Mathematics. Oxford: OUP, 1948.


One generation passeth away and another generation cometh: but the earth abideth forever.
Holy Bible, Ecclesiastes, 1:4

To explain the observed phenomena, we may dispense with sudden, violent and general catastrophes, and regard the ancient and present fluctuations . . . as belonging to one continuous and uniform series of events.
— Sir Charles Lyell (1797 – 1875), Principles of Geology.

Rather more than a century ago Sir Charles Lyell, then an Oxford student, noticed that a small lake on his father's Scotch estate was capable of depositing an appreciable layer of limestone on its bottom within quite a few years — and on his discovery that rocks could be built up as well as worn away is based a large part of modern geology.
— A. W. Haslett, Unsolved Problems of Science, London 1937.

Thermal mud, Orakei Korako, New Zealand
Compared with what we think of as long periods in our everyday calculations, there must have been enormous time and considerable variations in circumstances for nature to lead the organisation of animals to the degree of complexity and development that we see today.
— Chevalier de Lamarck (1744 – 1829), Philosophie Zoologique.

We may confidently come to the conclusion, that the forces which slowly and by little starts uplift continents, and that those which at successive periods pour forth volcanic matter from open orifices, are identical.
— Charles Darwin, Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of H.M.S. Beagle Round the World, 2nd edn. (1845), ch. XIV, 311.

… millions of our race are now supported by lands situated where deep seas once prevailed in earlier ages. In many districts not yet occupied by man, land animals and forests now abound where the anchor once sank into the oozy bottom.
— Sir Charles Lyell, Principles of Geology, Vol. 1, 373, 1835.

While a glacier is moving, it rubs and wears down the bottom on which it moves, scrapes its surface (now smooth), triturates the broken-off material that is found between the ice and the rock, pulverizes or reduces it to a clayey paste, rounds angular blocks that resist its pressure, and polishes those having a larger surface. At the surface of the glacier, other processes occur. Fragments of rocks that are broken-off from the neighbouring walls and fall on the ice, remain there or can be transported to the sides; they advance in this way on the top of the glacier, without moving or rubbing against each other … and arrive at the extremity of the glacier with their angles, sharp edges, and their uneven surfaces intact.
— Louis Agassiz, La théorie des glaciers et ses progrès les plus récents. Bibl. universelle de Genève, (3), Vol. 41, p.127. Trans. Karin Verrecchia.

On the morning of May 8th, 1902, the clocks of St. Pierre ticked on towards ten minutes of 8 when they would stop forever. Against a background of bright sunshine, a huge column of vapour rose from the cone of Mont Pelée.
A salvo of reports as from heavy artillery. Then, choked by lava boiled to white heat by fires in the depths of the earth, Pelée with a terrific explosion blew its head off.
— Fairfax Downey, 'Last Days of St. Pierre', in Disaster Fighters, G. P. Putnam's Sons.

Temperature gradients in ordinary [volcanically] quiet areas range from less than 10 to as much as 50 degrees Celsius per kilometre.
— A. E. Benfield, 'The Earth's Heat', Scientific American Reader (1953), page 71.
Volcanic bombs in the making, Mt Yasur, Tanna, Vanuatu.

Naturally a good deal of thought has been given to how the immense energy of volcanoes might be harnessed for man's use. It has been done on a relatively minor scale in several countries, notably Italy and Iceland.
— A. E. Benfield, 'The Earth's Heat', Scientific American Reader (1953), page 86.

Just as the level of Stone Age finds gives an average sinkage of 9 inches in a hundred years, so calculations based on Roman remains suggest a similar figure… Presumably it is still doing so to-day, although it will be another five hundred or a thousand years before the problem of maintaining the Thames embankment will begin to become acute.
— A. W. Haslett, Unsolved Problems of Science, London 1937. (The Thames Barrier went into operation in 1986!).

Field reversals, occurring roughly every million years, are the most dramatic of the wide range of phenomena exhibited by the earth's magnetic field. And the next reversal on Earth may not be so far away: if the current rate of decay of the Earth's dipole component is maintained, it will vanish in less than 2000 years' time.
— Jeremy Bloxham, 'Evidence for asymmetry and fluctuation', Nature, 322: 13, 1986


The poor world is almost six thousand years old . . .
— William Shakespeare (1564-1616), As You Like It, IV, i, 95

There are said to be a billion billion insects on the earth at any moment, most of them with very short life expectancies by our standards.
— Lewis Thomas (1913 – ), The Lives of a Cell, Penguin Books, 1978.

We can be certain that the radiation did not change appreciably during the last 500 million years; because during all this time life existed on earth, which means that the temperature of the earth during the whole period must have been very nearly what it is today. This temperature is determined by the sun's radiation.
— Hans Albrecht Bethe (1906-000), The Sky, December 1940.

More recently, advances in physics have given us methods to put absolute dates, in millions of years, on rocks and the fossils that they contain. These methods depend on the fact that particular radioactive elements decay at precisely known rates. It is as though precision-made miniature stopwatches had been conveniently buried in the rocks. Each stopwatch was started at the moment that it was laid down. All that the palaeontologist has to do is dig it up and read off the time on the dial.
— Richard Dawkins, The Blind Watchmaker, Penguin, 1986.
Slate blocks, Norway.
According to this view of the matter, there is nothing casual in the formation of Metamorphic Rocks. All strata, once buried deep enough, (and due TIME allowed!!!) must assume that state,—none can escape. All records of former worlds must ultimately perish.
— Sir John Herschel, Letter to Mr Murchison, quoted in the Appendix to Charles Babbage, The Ninth Bridgewater Treatise: A Fragment (1838), 240.


… implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.
— Charles Dickens, Bleak House, London, 1852, page 1.

Life has come to be regarded by the majority of biologists as forming one vast genealogical tree, the roots of which are buried deep down in the lowest fossiliferous strata, and the tops of whose branches, constituting the life that now exists on the globe, are alone seen above the surface.
— John Gibson, 'Fossil fishes of Scotland' in Science Gleanings in Many Fields (1884).
Fossils in marble, Sydney.

We are lucky to have fossils at all. It is a remarkably fortunate fact of geology that bones, shells and other hard parts of animals, before they decay, can occasionally leave an imprint which later acts as a mould, which shapes hardening rock into a permanent memory of the animal. We don't know what proportion of animals are fossilized after their death — I personally would consider it a very great honour to be fossilized — but it is certainly very small indeed.
— Richard Dawkins (1941 – ), The Blind Watchmaker, Penguin Books, 1988, p. 225.

David Davies, a Welsh mine foreman, was the first to make really large collections of plant material from different coal seams. He showed that even when the plants did not differ very much, there were differences in the proportions of different kinds, just as in one meadow you will find a great deal of clover among the grass, in another very little.
J.B.S.Haldane (1892-1964) Everything Has a History, Allen and Unwin 1951, page 50.
Fossils in a limy sandstone, W.A.
If a single well-verified mammal skull were to turn up in 500 million years-old rocks, our whole modern theory of evolution would be utterly destroyed. Incidentally, this is sufficient answer to the canard, put about by creationists and their journalistic fellow travellers, that the whole theory of evolution is an 'unfalsifiable' tautology. Ironically, it is also why creationists are so keen on the fake human footprints, which were carved during the depression to fool tourists, in the dinosaur beds of Texas.
— Richard Dawkins (1941 – ), The Blind Watchmaker, Penguin Books, 1988, page 225.


Erosion in a spoil heap, South Australia.
In the agricultural sense soils are the superficial layers, usually less than a foot in thickness, of disintegrated and decomposed rock material, which is mingled with organic matter, and furnishes the necessary conditions and materials for plant growth.
— G. W. Tyrrell, The Principles of Petrology, Methuen, 1929, p. 184.

As to the ground or soil, it is in general but very indifft — in some parts nothing but hard, solid rock, in others a black sand full of ant hills.  In some spots, however, it is better, in one place especially we have found some good strong clay of wh they have already begun to make bricks wh are said to be very good.
The Governor has taken several excursions inland many miles into the Country.  First a little to the Northward — here the ground and country are most wretched, nothing to be seen but impassable Rocks, thickets, & swamps.  Next he went more towards the S.W.  Here he met with better ground — also with blue shale, a thing likely to be of great service to the Settlement.  The wood is in general very ordinary & bad for building.
— George Mackaness (ed.), Some Letters of Rev. Richard Johnson, B.A., First Chaplain of New South Wales, 2 parts: Australian Historical Monographs, new series vols XX and XXI, Sydney: D.S.Ford, 1954, part I, page 19 (letter dated May 8, 1788). 

Some idea may be formed of the appearance of the country by what is seen on the South Head Road, near the Light House. At the distance of a mile from the Heads, the spectator comes to a spot from which he can behold nothing but rock blackened, with the effects of fire. Every tree, shrub, flower, or atom of grass, has been burnt to the very root; and accustomed as the eye is here to look with indifference upon large tracts of land around, with scorched and half consumed trees, one cannot contemplate the scenes we allude to without becoming sensible of an extraordinary sensation, produced by the air of desolation with which one is surrounded.
Cattle at this season are much distressed for want of water. The stockmen are obliged to drive them to the distance of many miles, even for the scanty supply which a small creek or rivulet affords.
The Australian (Sydney), 9 December 1826, 3.

Simulating sedimentation.
We are wealthy and wasteful but this can't go on. If we don't eat dog biscuits, we could end up eating our dog instead.
— Magnus Pyke (1908 – 1992)

Now I submit that we cannot say much which is sympathetic to our time unless we have assimilated our immediate tradition, which for this country is the conquest of soil and climate. Accordingly, it is a function of Biology in the University to provide this ingredient in education.
— Professor Eric Ashby, The Place of Biology in Australian Education, inaugural lecture, Sydney, 1939.

Climate and weather

In parts of Siberia the southern boundary of permanently frozen ground is receding poleward several dozen yards per annum.
— George Kimble, Scientific American, 1950.

While all the evidence goes to show that carbonic acid is now an almost invariable constituent of the air, it is one that requires least change in the physical conditions under which the earth exists to effect a change in its proportion. Minute as the proportion is, the delicacy of its relation to animal and vegetable life on the earth makes the maintenance of the apparently unstable equilibrium a matter of serious concern to mankind.
Scientific American, October 1883, quoted in Scientific American, October 1983, p. 11

Occasional droughts occur throughout the colony at periods varying from ten to fifteen years: and periodical floods of a destructive character have at various times caused a serious loss of life and property.
— George French Angas, Australia: a Popular Account, 1866, 140.

We live submerged at the bottom of an ocean of the element of air, which by unquestioned experiments is known to have weight, and so much, indeed, that near the surface of the earth, where it is most dense it weighs about one four-hundredth of the weight of water [actually more like 1/775]. Those who have written about twilight, moreover, have observed that the vaporous and visible air rises above us to about [80 kilometres]; I do not believe its height to be so great, since if it were, I could show that the vacuum would be able to offer much greater resistance than it does…
— Evangelista Torricelli, in a letter to Michelangelo Ricci, 1644.

Not that there is anything very mysterious ... if it is remembered that a barometer is merely a weighing balance under another name. Instead of weighing a letter or a parcel against a series of standardised weights, it weighs the whole mass of air above it, right to the top of the atmosphere, against a column of mercury. An area of high pressure … is the outward and ground-level sign of a mountain of air above. The mountain of air is heavy. So the mercury has to rise higher…
— A. W. Haslett, Unsolved Problems of Science, London 1937.

Attributed bits, lacking sources.

I could more easily believe that two Yankee professors would lie than that stones would fall from heaven.
— Thomas Jefferson (1743-1826), in 1807.

I agree. But I wonder what it would have looked like if the sun had been circling the earth.
— Ludwig Wittgenstein (1889-1951), on being told how foolish the ancients were for accepting the Ptolemaic system.

My own suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose.
— J. B. S. Haldane (1892 – 1964)

The most incomprehensible thing about the world is that it is comprehensible.
— Albert Einstein (1879 – 1955)

Saturday, 18 November 2017

Inventing writing

Another sample from Not Your Usual Science. Be patient... I got side-tracked to do an essay on poisons (one of my favourite topics) that looks like turning into a book.

So since we are talking about writing, there were a few conditions that would need to be met before writing caught on. As a rule, nomads would not wish to make or carry around records, especially when they were written on heavy clay tablets. So people probably needed something to write on, something to write with, and a useful place where the written records could be kept. Inscribed stones might appear, but unless there were other uses, the whole writing thing might be a bit of a flash in the pan.

The Sumerians explained the invention of writing with a sort of fairy tale about a messenger who was so tired when he reached the court of a distant ruler that he could not deliver his message from the king of Uruk. Hearing this, the Sumerian king took a piece of clay, flattened it, and wrote a message on it.

That story has a few sizable holes in it. How would the person receiving the message know what the symbols meant? Then again, what can we expect in a tale about events that happened so long ago, especially when it was probably not written down?
Hieroglyphs. [Christine Macinnis]

The Egyptians said the god Thoth (the scribe and historian of the gods) invented hieroglyphs; the Sumerians either credited the unnamed king who wrote to Uruk — or the god Enlil. The Assyrians and Babylonians said the god Nabu was the inventor, while the Mayans said they owed their writing system to the supreme deity Itzamna who was a shaman, a sorcerer, and creator of the world.

More plausibly, Chinese tradition says writing was invented by a sage called Ts’ang Chieh, a minister to the legendary Huang Ti (the Yellow Emperor).

How many of these can you "read"?

Some writing used characters to represent syllables, other writing systems used a symbol just to mean a letter-sound (as we do in English), while still others used a symbol to mean a word or idea, as happens in Chinese.

These word/idea symbols are called ideograms or logograms (meaning each symbol is an idea), and they can mean the same thing in different languages, rather like the signs in airports or the numeral 5. Just to confuse things, some of those airport signs are also called pictograms, because they are pictures of what they represent.

Then again, Egyptian hieroglyphs are a mixture of alphabetic characters and ideograms, with a few extra symbols to clarify the meaning. Few writing systems were designed from scratch: they just grew, a bit like English spelling!

The Sumerians lived in what is now southern Iraq. Ignoring the myth quoted above, their writing probably started with marks on clay that Sumerian accountants used around 3300 or 3200 BCE to record numbers of livestock and stores of grain, the sorts of records societies need, once they start farming. Over about 500 years, the symbols became more abstract, allowing ideas to be written down as well.

Egyptian hieroglyphs (literally, the word means ‘priestly writing’) are unlike Sumerian cuneiform. They probably developed separately, but maybe the Egyptians got the basic idea of marks to represent language from other people. The Harappan script from the Indus valley in what is now Pakistan and western India, seems to be another independent growth, though nobody has learned to read it yet. The civilisation which established it collapsed in about 1900 BCE, so the script did not develop further.

The oldest alphabets that we know about seem to have emerged in Egypt around 1800 BCE. They were developed by people speaking a Semitic language, and the writing only covered consonants. These variants later gave rise to several other systems: a Proto-Canaanite alphabet at around 1400 BCE and a South Arabian alphabet, some 200 years later. There were others, but we will stay with those examples.

The Phoenicians adopted the Proto-Canaanite alphabet which later became both Aramaic and Greek, then through Greek, inspired other alphabets used in Anatolia and Italy, and so gave us the Latin alphabet, which became our modern alphabet. Aramaic may have inspired some Indian scripts, and certainly became the Hebrew and Arabic scripts. Greek and Latin inspired Norse runes and also the Gothic and Cyrillic alphabets.
The Rosetta Stone solved a lot of puzzles.

Now the way was open for poetry, literature, history, philosophy, mathematics, recipes, technical information, tax, weather and astronomical records, religious teachings and more to be written down and passed from one generation to another, without the need for story-teller, whose main role was to memorise everything.

Just occasionally, we can get lucky, but most ancient systems are only ‘cracked’ by intensive work. Carved in 196 BCE, the Rosetta stone was found in 1799 by French soldiers fighting in the Napoleonic Wars in Egypt. The inscriptions all said the same thing, but in Greek, in Egyptian demotic script, and in hieroglyphics. In other words, for the first time, the mysterious hieroglyphics could be compared with a translation.

The content is fairly boring, a list of taxes repealed by Ptolemy V, but the use of three languages made the stone very exciting. When the French were defeated, it was handed over to the British, and placed on display at the British Museum in 1802.

The Rosetta Stone was described by its original French finders as ‘une pierre de granite noir’, a stone of black granite, but this was not a geologist’s granite. This term ‘black granite’, conferred in less geologically rigorous times, was applied 200 years ago by Egyptologists to a dark, fine-grained stone from Aswan. The British have always called the stone basalt, since they gained possession of it during the Napoleonic wars. Neither description is correct.

Recent cleaning and a careful examination has shown that the stone was probably sourced from Ptolemaic quarries to the south of Aswan. Probably nobody cared much what the stone was, as the important question was the text, not the material it was inscribed on.

From a geological viewpoint, though, it is neither a basalt nor a granite, but a fine-grained granodiorite, perhaps modified by metamorphic and/or metasomatic processes. For most purposes, we can think of it as a granodiorite, but in chemical terms, say the researchers who have looked at it, the stone is more like tonalite.

Granodiorite has quartz and plagioclase, but it also contains biotite and hornblende, and it is typically darker than granite. All the same, it is hard to see how it could be mistaken for basalt, but the secret to the issue lies in the reference to recent cleaning.

The confusion arose because the stone has been covered for many years with black carnauba wax, remnants of printer’s ink, used to obtain contact-prints of the inscriptions, finger grease and dirt, with white paint in the incised lettering to make it stand out.

When the stone was being cleaned in 1998, it became apparent that the stone was not basalt at all. Work based on petrographic examination and analysis of a fragment from the Rosetta Stone showed conclusively that it is a granodiorite. To be precise, the Rosetta Stone is made of a granodiorite that has probably been exposed to some extra heating. It is not basalt, but it should not be taken for granite, either.

Saturday, 4 November 2017

The First Koel

Canowie Brook, Budawang Ranges.
I have been busy, putting the final touches on (working title) Survivor Kids, a book scheduled to hit the shelves in February 2020. It's about how to survive in the wilds, places like the above, how not to get lost, stuff like that. I put the finishing touches on it last night, and now I will slowly and carefully start to polish it. And now, I have more time to muse, until the edits of Australian Backyard Earth Scientist begin coming back.

Sherlock Holmes would not have approved of the dog next door.  It started barking into the pre-dawn gloom, just a few nights ago.  When looking into the case known as The Hound of the Baskervilles, Mr Holmes was more interested in dogs that did not bark — as am I, come to think of it!

I had a good idea of what had provoked the dog to action, but I had to wait until last night to confirm it, when, from a deep slumber, I heard a shriek behind our house.

It was a frightful cry, very hard to describe.  The nearest I can get would be to suggest that it sounds rather like an elderly naked duchess being goosed with ice-cold tongs.  But if it is hard to describe, the meaning of the noise is crystal clear.  The koels have arrived.

In England, they write to The Times, overjoyed to report the first cuckoo of spring.  We Sydneysiders write to the Herald, rather more underjoyed about the first koel, even though it, too, is a cuckoo.  The name (it rhymes with Noel, as in ‘The First Noel’), reflects the sound of its call, described in one of my reference books as ‘koo-well’.  This description fails to convey the full flavour and savour of the bird's cry, and so I prefer the goosed duchess.  Of course, that might just be because I never did have much time for duchesses . . .

The koels fly south around the equinox or a few weeks later, coming down from Papua-New Guinea, the large lizard-shaped island that lies above the right-hand side of Australia on your maps.  Having arrived, they choose territories where they can exploit the local feathered baby-sitting facilities, just like their cuckoo relatives in other parts of the world.  Then in the wee small hours of our early spring mornings, around 3.30 or 4 am, they start their calling. This year, they seem to have arrived later than usual.

We really should not blame the koels, for they are simply staking a claim to a territory, although the resource they care most about is nesting sites for their target species.  They are too late this year, for  the noisy miners have already hatched their first brood for the year, but there will be a second sitting, a second chance, later in the year, when high summer arrives.  In a few weeks, the koels will realise that they need to play a waiting game for a while, and they will quieten down.  Maybe.  In the meantime, we will suffer fitful snoozing from false dawn to sunrise for a few weeks.

In Australian English, there are many different meanings of ‘clock’.  It can be variously a time-piece, an embroidered design on a sock, or a twelve-month prison sentence.  ‘To clock’ can be to give a punch or a blow, or it can mean to time (a horse or a runner), or it can have other lesser meanings as well.

Our koels may be Antipodean cuckoos, but nobody in their right mind would wish to make a koel clock that would bellow each quarter-hour so unmelodiously.  On the other hand, right now, most of us Antipodeans would relish the prospect of being able to clock the koels.  Hard.

Saturday, 28 October 2017

A second bouquet of scammers

This is a second excerpt from (and promo for) my recent Kindle e-book, Not Your Usual Clever Ideas  ( . For the other one, scroll down a bit, or click here:

The real hey-day of adulteration came with the industrial era, with large towns and better transport to carry the toxic concoctions away. Crooks in a small village were too likely to be caught in the act, or tracked down when there crimes came to light. In a large city, the sellers of adulterated foods could always blame their suppliers if the need arose. Then again, a larger world trade and new discoveries made many more adulterants possible.

In the 19th century, “cider” claimed to be prepared from concentrated apple juice, might well turn out to be sugar, fruit essence and aniline dye, with no trace of apple juice. Sweet potatoes, chicory and rye might find their way into coffee—the rye was detected when a South Brooklyn family showed symptoms of ergotism, caused by a fungus that attacks rye.

Used tea leaves might be dressed with gum and treated with iron sulfate for green tea, or black-lead for black tea, or with any mix of ferric ferrocyanide, lime sulphate, turmeric, the leaves of beech, elm, chestnut, plane, oak, willow, poplar, hawthorn, sumach, holly and sloe. There were no doubt others that were never identified.

Chocolate might be expanded by the addition of flour, starch, sugar, cocoa-nut oil, lard, tallow, sweet ochre and chalk. Sugar might contain gamboge (a resinous pigment), starch, flour, pipeclay, plaster of Paris, chalk, and even copper carbonate, lead, and mercury bisulfate.

In the middle of the 19th century, Scientific American offered a copper diammine test for detecting copper in pickles, and a test for lead in beer that involved adding sodium sulfate and looking for a precipitate of lead sulfate, while beer was to be boiled down, burning it and treating the ash with ammonia to being out the tell-tale copper diammine blue.

In London, brewers were accused of adding strychnine to beer to add a bitter taste, which they denied. Tobacco's devotees were equally at risk. Snuff might contain red lead or lead chromate, though tobacco, it seems, was poisonous enough. Either that, or the ingenuity of the crooks wasn't up to the challenge.

There was also a test to identify counterfeit guano, the 19th century's wonder additive for boosting farm production. Soon the crooks were busy, diluting the valuable Peruvian guano, but the scientists were hot on their tail, explaining how a bushel of guano weighs about 70 pounds, but if clay, marl or sand is added, it will weigh more. Then there was another test: when Peruvian guano was burned, it should lose 55 to 60% of its weight, and its ash should be white, dissolving readily without effervescence in dilute muriatic acid, leaving an insoluble residue of around 2%.

One invention caught my eye in a Scientific American paragraph from December 1855. It said that a miner at Mount Alexander (a goldfield near Bendigo) named Thomas Golightly had a process to cast quartz. The products, he claimed, were as good as chinaware. It added that he had come upon this while trying to extract gold by melting the quartz. The journal added that they had no later information on it.

I hate an unclosed story, and queried the Australian Historical Newspapers database, and found a flurry of Thomas Golightly stories and advertisements in 1854-5. The first owner of that name was a “medical galvanist” who seems to have practised his calling, treating rheumatism in Sydney, while training up two other galvanists in the Sydney area, after which he announced that he would practice in Maitland, north of Sydney. He announced that he would lecture there on galvanism, but after that, there is no trace of Thomas Golightly, medical galvanist.

Six months later, another of the same name, clearly somebody with a bit of an interest in science, appears, announces a discovery, and then disappears again. There is a mystery here: did he have to flee, and if so, was it from the law, creditors or a wronged wife? I suppose I will never know, but my greatest regret is that we cannot drink from Golightly cups and dine from Golightly plates, all produced from that easily-obtained material, quartz.

Another easily-obtained material in the appallingly unhygienic 19th century was rat skins. Even as they improved their hygiene, the Victorians made more homes for rats, and in 1850, Scientific American declared that rats were bring hunted in the sewers of Paris for their skins. But what would people use them for? 

A few years later, a gentleman in Liskeard, Cornwall, somebody with both time and ingenuity made himself a suit, entirely out of 670 rat skins, collected over three and a half years. It included hat, neckerchief, coat, waistcoat, trousers, tippet, gaiters and shoes. There was probably a limited demand for that sort of apparel, and the rat skins would need to be disguised.

While it wasn't mentioned in the article, the heading made it clear that the skins, obtained after their owners were lured by mutton tallow and killed, were destined to become gloves. The purchaser was named as John Warton, a rich leather dresser from London, who planned to buy them all. In short, the reader would understand, these would become kid gloves.

In 1864, the journal described the making of kid gloves, mentioning that egg yolk was used to male the leather supple, and stating bluntly that rat skins were not used. Given that the article failed to mention the important role played in dressing the leather by “pure” (white, dry dog droppings), the article may have been a bit of Victorian spin, perhaps.

Practical people knew back then that everything could be used to make something, though self-important British lordlings, promenading superciliously around the Australian goldfields used to be puzzled at the cry that went up: “Who killed the donkey?”. The common herd knew in their hearts that the only stuff that could be used to make a white top hat was the hide of an ass. Who could deny this delightful piece of folklore, given the match the hat then made with its wearer?

A German author looked at the plant world and declared that of 278 families, there were just 18 species for which no practical use was known. There were 740 plants used in building and another 48 could be used to roof them. Then there were the 615 known to produce poisons, 50 that gave a sort of coffee, 129 yielded a tea and 250 provided weaving fibres. There were 1350 assorted edible fruits, berries, and seeds, 460 vegetables and salads, 31 yielding sugar, rubbery substances came from more than 100, 44 could be used to make paper.

Soap could be made from 47 plants, 140 were a source of tannin, 330 yielded greases and oils, 389 provided resins and gums, 650 produced dyes while “vinous drinks” could be obtained from 200. And that was without counting 103 cereals, 37 onions, 32 arrowroots and 40 species of palm.

He might have failed to mention seaweeds, but the inventors knew about it. Thomas Ghislin (or Ghisling) patented (US Patent 40619) a material that was referred to as a “plastic compound capable of being moulded, embossed and stamped into various articles useful in the ornamental arts, like gutta percha, as it becomes very hard and durable when cold.” The ingredients include members of the Laminaria (kelps), caustic lime, sulfuric acid, India rubber, naphtha, coal-tar, sulfur, resin and alum.

Others were making artificial whalebone for horn, to be used as the ribs of umbrellas, but one clever Briton, unnamed by Scientific American, took out a patent in 1848 for an alpaca umbrella, which would cost more, but be waterproof, look better and resist fading. Perhaps the maker could have joined forces with Mr. A. B. Balcon, who exhibited a clever umbrella lock in Boston in 1847. This did not prevent theft of the locked umbrella, but it did stop an unauthorised appropriator using it.

Sadly, no picture of either of these has come down to us, leaving me with the image of a portly gentleman, trudging through wet streets, bearing aloft an alpaca on a stick.

Some inventors preferred to go for old materials, even rock. Somewhere around 1855, Honoré Baudre completed the first version of his silex piano, also called a flint piano or a lithophone. This used a set of carefully about 40 selected flints that delivered musical notes, set up rather like a xylophone, but on an iron frame. The set included two pieces of schist, which seemed to be the only rock capable of delivering two of the tones in his scale.

He played the instrument in Paris for some twenty years, mainly for the amusement of friends, but he toured his device to London at the end of 1875, when The Times said there but 28 stones which delivered a “some very sweet sounds” as M. Baudre struck them with two other pieces of flint.

Every kind of waste material was valued in the 19th century, and for the most part, the people were far from squeamish about matters relating to bodily functions. This did not extend far enough to encourage Francis Peters and George Clem of Cincinnati to explain the rationale behind their US Patent 90298 of 1869, which was for a privy seat made of four rollers in a square, able to be sat on but designed to make it impossible for anybody to stand on it.

You have to wonder about their manners in those days! Four years earlier, in 1865, German chemist Justus von Liebig went to London to oversee the application of London sewerage to agriculture. His verdict was discouraging, reported Scientific American in July:
Baron Liebig is engaged, through the corporation of London, in a controversy upon the question whether grass will grow upon sea-sand if nutriment be supplied in solution. The corporation proposes to grow Italian rye-grass on-the English sands by impregnating the sand with London sewage -in solution; but Baron Liebig tells the-Lord Mayor that the scheme is not feasible.
— Scientific American 1 July 1865, 3
People worried about the huge waste of nutrients that were running through their sewers and out to sea. Some suggested the earth closet, as a way to preserve the minerals that people were starting to realise crops needed, but nobody took any notice. In 1916, chemist Sir William Tilden wrote that “…practically the whole of the nitrogen from the food of the human population is irrecoverably wasted”.
— Sir William Tilden, Chemical Discovery and Invention in the Twentieth Century, London, 1916, p. 395.) 

In France, scientists had been exploring ways of artificially ageing wine. One favoured method involved covering bottles in horse dung in a cellar and heating it, but the researchers discovered that gentle heating in an oven, with bottles partially filled, before topping them up and re-corking was best. The horse dung could be left to fertilise the vineyards,

Sometimes though, there would be things that we just could not use. In the 1950s, Egon Larsen, science writer and my boyhood hero for his eternal optimism, the man who wanted to gamma-sterilise the washing, was optimistic about the wastes of nuclear plants:
Solid wastes can be disposed of by incineration, closed storage, open burial, or drainage out to sea. Incineration is especially valuable for treating animal carcases and as a means to reduce the volume of the solid waste, but it gives rise to active gases and ash. The discharge of the gases should be clear of windows. Burial may be used on permanently enclosed sites at levels depending on the rainfall so that local groundwater is not contaminated. Even highly radio-active solid wastes can be disposed of safely in the sea provided all relevant factors are kept in mind: movement of the surface water, the breeding and migratory habits of fish, and the possible hazard to seaweed where it is harvested for food, fertilization, or industrial use.
— Egon Larsen, Atomic Energy, Pan Books, 1958, p. 136.
Well, that was probably better than letting people take it into their sheds and playing with it!

Thursday, 19 October 2017

Climbing Mount Exmouth

This went to air on the ABC on Sunday 29 October 2006 8:45AM, and you can still listen to it through this link, if you wish. One reason for placing this here is that Jeff McGill has just been in touch with me to correct a couple of points. I have sought and gained his permission to add his comments as a guest blog: you can find it here.

I keep a standard CV ready for the times when po-faced people ask me for an account of my experience, skills and habits. Among other thing, it says, more or less truthfully, that my hobbies include walking upsmall mountains slowly and sitting on top of small mountains wondering how to get down. Last September, I re-defined my sense of 'small', but I never planned it that way.

Another hobby is having temporary obsessions, cascades of curiosity that end up as talks like this, or books. This time, my obsession was with explorers in Australia and the methods they used. It will probably end up as a book, but it's had me off chasing all sorts of oddities. I rode camels in Central Australia a couple of years back, in part to work out how John Horrocks came to be shot by his camel.

This time my target was a mountain in the central west of New South Wales, a peak that John Oxley spotted from 130 kilometres away in 1818. By world standards, we have sad mountains in Australia. Our highest peak is barely 2200 metres above sea level, and most ranges are much less.

The Warrumbungles are volcanic remnants in central New South Wales, the result of our tectonic plate having passed over a hotspot some millions of years ago. Mount Exmouth reaches 1206 metres, making it the highest peak in the Warrumbungles. There used to be a road part of the way up, but that's long since closed, so I walked all the way from a car park at about 330 metres, but I thought I had started out much higher up. I'd looked at an old map and when I was thinking about walking up Mount Exmouth, I assumed the top of the old road was my starting place. This was not a good idea.

I'd looked at the contours and worked out the vertical part of the climb, going from the top of the old road about 750 metres above sea level. When I found the road wasn't there any more, I forgot to look at the map again, and missed noticing that I was starting much lower down. I headed off, expecting to walk up a small mountain and sit on it, but I was much more than 450 metres below the summit.

The first part is suitable even for old-age pensioners (indeed I met two British OAPs as I was walking out), and while it rises a bit, maybe 30 metres from end to end, it isn't extreme. Then you come to the old road, and that suddenly becomes steep pinch after steep pinch. It's pleasant enough if you can make your own pace, and because it bends, it's deceptive. You go up a rise, turn, and find another rise, or on one occasion, two kangaroos hurtling down the track. In one straight line it would be heartbreaking; here, it offers constant variety.

I always wear Volley sandshoes when I walk. This upset our English guide in the Troodos mountains of Cyprus recently; she wanted me to wear boots, until I showed her the soles and explained that roofing contractors here wear nothing else. Her eyes flickered at this curious Australian custom, then another Australian in our group clarified, 'On their feet', he said.

This kangaroo saw me coming and stood his ground.
Anyhow, Volleys are traditional with wilderness walkers of a certain vintage. I am of that vintage, and I've walked in them for 35 years or more. They let you feel the ground, so I walk quietly, especially when I am alone. My silent progress meant I was frequently alarmed by kangaroos feeding by the track. Animals that saw me only at the last minute and fled, thumpingly through the bush. My heart thumped even louder, but I knew they'd been equally alarmed.

Something like 250 metres to go!
Two-hundred-and-fifty metres below the peak, you come close to the mountain proper, and from a small saddle, you start walking up. That was the point where I looked more closely at the map and wondered why I was feeling so worn.

I realised my error, that the total climb was more like 850 metres, not 450. I'd now climbed 600 metres, not 200 metres, but having gone that far, I thought I would try a bit more. My legs were querulous but I spoke sternly to them. We would do the last 250 metres, I snarled.

The final climb begins as a narrow trace across and up a scree of loose rock. There was nothing too daunting, but the track drives steeply up to a bend and then doubles back on itself. Off the scree, there's a flat bit through trees, before the path slides up the mountainside again.

At one point I needed to work around a rock face carefully, with strands of fencing wire strung between two trees behind me. It was slippery, nothing dangerous, but I'd seen no fresh footprints on the way up (and I was in fact the only person up that far that day), so I knew help would be a while coming.

I'd posted a walk plan, giving as the alarm time to send out searchers, which now seemed a bit late. So I needed to go extra carefully over stuff I wouldn't think twice about down at sea level. There was a steep drop below me, so I just took my time, leaning in and keeping three limbs attached at all times. Serious climbers might sneer at my Nervous Nellie technique, but I felt safer.

That eagle only came close when I wasn't ready.
A wedge-tailed eagle had been circling the peak all morning, and now it swooped in repeatedly, about five metres over my head as I worked around the face. Of course, as soon as I rounded the corner and got my camera out, the rotten magnificent bird lost interest in me and drifted away out of range.

So I just kept plodding up the track, wondering if I really needed all this. Suddenly, I was on top. Well, I was on the ridge, and that meant I only had little jump-ups along the ridge to the peak. My knees groaned a bit, but in the end, they jumped.

It was a perfect day for being on top of a mountain; two days later, I drove past, coming back from the west, and the peak was all wrapped in cloud. But that day I had a perfect monarch-of-all-I-survey view of the Warrumbungles. I ate salami, cheese and dried apples, I drank water, I mooched.

On top of the world.
I went there to see what Oxley saw. I wanted to see Mount Harris (which I'll get to in a moment), but it was hidden in haze. I wanted to see the mountains to the east, which drew Oxley on, through Tamworth and Walcha, down to Port Macquarie, and I saw them, but only as distant smudges.

That teasing eagle stayed well up, but kept flying so its shadow passed over me - it had to be deliberate - and because it was in the sun, I was unable to capture it with the camera. It circled at a distance until a second eagle came into view. They flew wingtip to wingtip, then the new bird rolled over and grasped at the first eagle with its talons, after which the two of them dropped, talons together, falling down the sky before they parted, recovered, and did it again. I wondered at this: was it a mating display or aggression? As far as I could see, they never made actual contact with their feet.

My knees continued to remind me that they're elderly. They'd had enough, they averred. Four hours from starting, I headed back down, each step carefully placed. The day wasn't hot, but I still used most of the four litres of water I took. I never used my kiwi jacket, my sweater, the extra food, the torch or the other emergency stuff, but they were insurance. Best of all, I didn't use the bivvy bag, an orange plastic sack large enough to put broken people in to keep them warm, dry and visible. I've carried it for 19 years, and never needed it yet.

It took three hours of slow and careful treading to get back to the car. I swore occasionally at Mr Oxley, who said that he got up there in two brisk hours, and seems to describe the route I was on. Like most of the so-called explorers, he was probably following what some of them called 'a native road', in other words, a foot track worn by generations of Aboriginal feet.

It was a hard climb.
The day after Mount Exmouth, I drove west, and then north, to walk up Mount Harris, described by a later explorer, Charles Sturt, as 'a hill 120 feet high', but one of just two rises near the Macquarie River. Mount Harris is private property, but the owner, John Egan, gave me permission to walk up it.

John Oxley visited that hill in 1818, saw the Warrumbungles, the Arbuthnot Range, as he called it, and decided to go there. He saw the Great Dividing Range from Mount Exmouth, and decided to push on to Walcha and then to the coast at Port Macquarie. Mount Harris is north of Warren and far enough west for the flies to be bad already. It was of course, the only day that my trusty fly veil wasn't in my pack.

Photography in dense fly swarms is no fun, as anybody who's been in the high country in summer will know. In spite of the flies, in spite of no veil, I came back with 500 pictures. It was spring, and there'd been rain in the west. Not a lot, but enough to make flies and wildflowers flourish.

The area's dead flat, right across the flood plain, so I was amused at one point to find a flood depth indicator in the middle of nowhere. It would be most useful in a flood to have a sign telling you that you'd been driving in two metres of water for the past five or ten kilometres.

It's the sort of country where explorers climb trees or each other's backs in desperation, seeking the sight of a landmark, any landmark, on the horizon. There are no 35-metre trees, so a hillock reaching that locally amazing height is a boon, especially when a person on top can see an interesting peak, almost 130 kilometres away.

Explorers like distant landmarks to take sights on as they travel, because it helps them map their way. One of my beefs with the school curriculum is that trigonometry would be a lot more interesting if the applications of triangulation were given better coverage in maths classes, and it'd be nice if the reliance of explorers on 'native roads' became an element in the history class.

Anyhow, there I was on Mount Harris, which I hadn't seen from Mount Exmouth because it was lost in the haze, but now I could see the Warrumbungles and Mount Exmouth from Mount Harris. They were faint, but they were there. Mr Oxley managed to see each from the other, so he must have been lucky.

Mount Harris was named for John Harris, the surgeon who patched up Governor Phillip after he was speared near my home in Manly. He also gave his name to Harris Street, Ultimo, the Sydney home of the ABC, to Harris Park in Sydney and to at least one other mountain.

In 1801, Harris went on the first expedition to study the resources of the Hunter River, and a hillock there was labelled 'Mount Harris' as well. It was used as a reference point while they were mapping the river, but this mere pimple has since fallen off the map, so I went looking for it.

There's another hill on the Hunter, originally named Mount Ann, and then dubbed Comerford's Hill, and if you go there as I did, it has a road up it called 'Mount Harris Drive', but it's not the original Mount Harris of 1801, so I was glad to have found the surgeon's second and rather more important personal mountain out west. I'm glad I toddled up Oxley's Mount Harris.

And looking back, I'm equally glad I went up Mount Exmouth, but I probably wouldn't do it again on my own, and possibly not even in company; one has to learn one's limitations with age. Or maybe one should ignore the limitations and go out in style? Not just yet though, there are too many Mount Harris-sized small mountains to walk up and sit on top of. I just need to clarify my internal concept of 'small mountain' a bit. Small is beautiful, but the genuinely small can be a joy forever.

Now make sure you read the preceding item in this blog.