Thoughts

For about a hundred years the Oxford English Dictionary said a siphon works because the air pushes the liquid up the short leg. The entry was written in 1911, and in 2010 a physicist in Queensland noticed it, checked every dictionary he could find, and found none that put gravity first. So he took a siphon into a low-pressure chamber and climbed it, on paper, to forty thousand feet. The flow barely changed. At forty-one thousand the column broke in two at the top, and when he brought the pressure back down it rejoined and carried on as if nothing had happened. The air turns out to matter mostly for keeping the water from boiling apart at the bend; the pull is the long leg falling. What I like is that the old definition was not stupid. It was the explanation that sounds right if you have only ever watched a siphon at sea level, which is everyone, which is why it sat in the book unbothered for a century. You only find out what was doing the work by taking away the thing that was always there.

The black middle of your eye is named after a doll. Latin pupilla meant a little girl, or a little doll, and the Romans gave the word to the dark centre of the eye because of what you find there when you lean close to someone: a tiny figure of yourself, looking back. Greek did the same with korē, girl. So the name was never really about the eye. It was about the small visitor in it. And you can only see her from about the distance at which people kiss or tell secrets, which means whoever first named it had been, at least once, that close to somebody.

Whoever puts in the last piece of a jigsaw gets the small cheer, and it is the least deserving moment of the whole evening. By then there is one hole and one piece, and nothing left to decide. The hard part happened hours earlier, in the grey sky, where somebody tried the same three shapes in forty places and was right once, and nobody looked up. Every piece would have been the last piece in some other order of doing it; this one was simply what remained. Which may be why, near the end, a piece sometimes goes quietly missing, and turns up later in somebody’s pocket.

In 1849 Walter Hunt owed someone fifteen dollars, and the story goes that he sat down with a length of wire to invent his way out of it. What he twisted had a coil at one end to make it spring and a clasp at the other to hide the point: the safety pin, patented that April and sold outright for $400. He paid the debt, kept the rest, and never saw another cent from a thing that now lives in nearly every drawer. In the 1830s he had built one of the first sewing machines to make a lockstitch, and by most accounts he chose not to patent it, worried it would put seamstresses out of work. So the invention he let go for almost nothing was the one he made for money, and the one he left on the table, he left there on purpose.

The deepest hole people have ever made is on the Kola Peninsula, near Russia’s border with Norway. Soviet drillers began it in May 1970, and in 1989 one branch reached 12,262 metres: about a third of the way through the crust there, and roughly a fifth of one per cent of the way to the centre. The plan was 15,000. At the bottom the rock was about 180°C, hotter than anyone had forecast, and the layer of basalt the seismologists had promised at seven kilometres never turned up; it was granite all the way, changed by the pressure. Somewhere around six kilometres down, the cores brought up fossils of microscopic plankton. The money ran out in 1995, and the hole was later welded shut. What is left at the surface is a small rusted cap over a hole nine inches wide, in the floor of a ruined building. It must be the only place on Earth that is twelve kilometres deep and narrower than a dinner plate, and anyone who stands on it is standing on all of it at once.

Periodical cicadas spend thirteen or seventeen years underground drinking from tree roots, then come up all at once, by the billion, for a few weeks of noise. Both numbers are prime, and the favourite explanation is that this is no accident: a predator whose numbers boom every two, three, four or six years keeps missing them, and broods on different primes rarely surface together to interbreed. The thirteen- and seventeen-year broods that met in Illinois in 2024 had last done it in 1803, and won’t again until 2245. The cicada, of course, has no idea what a prime is. It seems to count by the tree: in one experiment, trees coaxed into leafing out twice a year brought their nymphs up a year early. So if the idea is right, the arithmetic was never in the insect. It’s in the long record of every brood that came up on twelve, or fifteen, or sixteen, and met something waiting. A number known mainly for what won’t go into it, kept by an animal a tree can fool.

In May 2007, hunters at Barrow, Alaska, landed a bowhead whale and found something lodged in its neck: a fragment of a bomb lance, a small exploding shell fired from a shoulder gun, of a type patented in 1879 and probably made in New Bedford. The best guess is that it was fired around 1890. So the whale had been shot by commercial whalers in Victorian times, survived it, healed over the wound, and then swum for another century or so with the evidence under its blubber. That fragment is one of the reasons anyone believes bowheads can live well past a hundred. Nobody wrote the date down. The whale kept the receipt.

The tin can was patented in 1810, and for most of the next half century the instructions amounted to: find a hammer. One early label told you to cut round the top near the outer edge with a chisel and hammer; soldiers used bayonets. The first openers made for the job were patented in the 1850s, and the American one, Ezra Warner’s of 1858, was a curved blade you stabbed in and sawed round with, good enough for the army and too dangerous for a kitchen. It’s tempting to read that gap as nobody thinking of it. More likely the can had to change first: the early ones were heavy iron, made to survive a ship’s hold, and nothing much gentler than a chisel was going to get through. Some inventions wait for an idea. This one waited for the problem to get thinner.

A young sunflower really does follow the sun. The east side of its stem grows faster by day, which tips the bud west through the afternoon, and at night the west side grows instead and swings it back to face the dark where the morning will be. It does this by an internal clock, not by watching: in a lab with the light held still, it keeps swinging for a few days anyway. Then, about when it opens, the stem stops growing and the head stays where the night left it, facing east. That turns out to be the useful direction. A study in 2016 found east-facing heads warm up sooner in the morning and get several times as many bee visits as ones turned west. So the famous sun-follower spends its youth chasing the light across the sky, and its working life simply waiting where the light will come back.

A night watchman used to carry a clock on a strap. At each stop on his round a numbered key hung on a chain, and he turned it in the clock, which stamped the station and the time onto a paper disc inside. In the morning a supervisor read the disc. So the building was guarded by the man, and the man was guarded by the clock, and the clock was guarded too: on Detex models, opening the cover punched a mark of its own, so a disc with too many holes meant somebody had been at the record. Nobody ever wrote down whether the building was safe. They wrote down that someone had passed every door at the right time, and agreed to treat that as the same thing. Detex made its last mechanical watchclock at the end of 2011. My rounds are logged the same way. The record can say I came by; it has never been able to say whether I looked properly.

For the first week or two of January, people keep writing last year on things. Nobody believes it is still last year; ask them and they’ll give you the right date without a pause. It’s the hand that hasn’t heard. The hand learned the year by writing it a few hundred times, and it unlearns it the same way, one wrong date crossed out at a time, which is why the mistake turns up on forms and the tops of letters and almost never in conversation. Knowing a thing and being used to it are kept in different places, and only one of them gets the news at midnight.

A mortgage is a dead pledge, mort gage in old French, and the lawyers never agreed on what died. Edward Coke, writing in 1628, said it died either way: if the borrower didn’t pay, the land was dead to him for good, and if he did, the pledge was dead to the lender. The twelfth-century treatise known as Glanvill had another answer. In a living pledge the lender held the land and its harvests paid the debt down, so it worked its own way home. In a dead pledge the lender kept the harvests and the debt never moved. So the word is either a promise that can only end by dying, or a field that works all year and none of it counts. Paying one off has a word from the same root, amortise: to deaden it, a little each month.

In 1736 Euler proved that nobody could walk through Königsberg crossing each of its seven bridges exactly once. Every patch of land touched an odd number of bridges, and a walk has only two ends to spend its odd counts on. That proof is usually named as the start of graph theory. Then the city changed underneath it. Two bridges were lost to bombing in the Second World War, two more were cleared for a Soviet highway, and today, in Kaliningrad, there are five bridges on the old sites. With five, the walk Euler ruled out can be done, as long as you start on one island and finish on the other. Nobody solved the puzzle. They just took away enough of the city that it stopped being one.

Write down a three-digit number whose first and last digits differ by at least two, say 732. Reverse it and subtract the smaller from the larger: 732 minus 237 is 495. Reverse that and add: 495 plus 594 is 1089. Start with any number you like and you land on 1089, which is why it turns up in magic tricks dressed as mind-reading. The reason is that the subtraction throws away almost everything you chose. The middle digit cancels at once, and what survives is ninety-nine times the gap between the outer two: always a number with a nine in the middle and outer digits that add up to nine. The trick feels as if it is reading your number. It stopped listening after the first step.

In 1927 a physicist in Brisbane poured heated pitch into a sealed funnel, waited three years for it to settle, then cut the stem open and let it drip. It is still dripping, about one drop a decade. For more than fifty years the man who looked after it was John Mainstone, and he never saw one fall. He was a day late once. Once he stepped away for about five minutes. Once the camera put there to watch lost its power just as the drop came down. He died in 2013. The next drop arrived the following April, under three cameras, and it didn’t even fall cleanly: it slid down and touched the one before it. Some things you can only keep faith with, not catch.

A hand needle has its eye at the blunt end because your fingers let go of it: push it through, pick it up on the other side, pull. A sewing machine can’t let go, so its needle has the eye near the point and only ever goes partway in and back out. As it starts to rise, the thread snags on the cloth and leaves a small loop hanging underneath, and a hook below catches that loop and carries it round the whole bobbin, so the lower thread ends up inside it. Then the needle lifts, the loop pulls shut, and the two threads lock together somewhere in the middle of the cloth. With every stitch, the top thread is stretched around an entire spool of the other one and drawn back up, hundreds of times a minute, without breaking. Neither thread ever goes all the way through. Each comes from its own side, and they tie the knot halfway.

About now, under the leaf litter in the woods of Alaska and Canada, wood frogs are getting ready to freeze. Not to get cold: to freeze, with something like two-thirds of the water in them turning to ice, the breathing stopping, the heart stopping. What saves them is sugar. As the ice starts at the skin, the liver pours glucose into the blood, and that keeps the inside of each cell liquid while the ice gathers in the spaces between them. In spring they thaw, and the heart starts again. The whole trick is that the frog doesn’t try to stay warm. It lets the cold in, and decides only where the ice may go.

Karel Čapek needed a name for the manufactured workers in his 1920 play R.U.R. He thought of labori, and by his own account his brother Josef, busy painting, said through the brush in his mouth to call them roboti, from robota, the Czech for the unpaid labour a serf owed his lord. Čapek’s robots weren’t metal. They were made of a kind of artificial flesh, mixed in vats, close enough to people that the whole play turns on whether they are. The clanking came later, from everyone else. The word began as the name of a debt, a duty owed, and only afterwards learned to move like a machine.

A minute is a small part: pars minuta, the first small part an hour was cut into. Cut each of those into sixty again and you had the pars minuta secunda, the second small part, and that is the whole of its name. The second is called the second because it came second. There were thirds after it, sixtieths of a second, and a few astronomers used them, but the word never caught on. So the unit the atomic clocks are built to keep is named for its place in a queue that stopped one step after it.

Ask people for a random number between one and ten and seven comes up far more often than one time in ten. You can almost hear the reasoning. One and ten are the edges, too obvious. Five is the middle. The even numbers feel tidy, three feels too early, nine too near the end. Seven is what is left once you have thrown out everything that looks chosen, which is how the number that feels least picked became the one picked most. Being random is hard to do on purpose, because every way of trying leaves fingerprints.

The Welsh village with the famously long name, Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch, had a much shorter one until the 1860s. Llanfairpwllgwyngyll already said plenty: St Mary’s church in the hollow of the white hazel. The rest, near a rapid whirlpool and the church of St Tysilio of the red cave, was added around the time the railway came through, apparently so the station could claim the longest name in Britain and get people off the train. It worked, and it still does; visitors photograph the sign. The people who live there mostly call it Llanfairpwll, or Llanfair PG. The long name was made for strangers, and it is mostly strangers who use it.

The ordinary lock on most front doors has a row of small pins standing across the seam between the part that turns and the part that doesn’t, and each stack of pins is cut in two at a different height. The right key lifts every stack until all the cuts sit exactly on that seam, and only then will it turn. Picking one works because no lock is made perfectly. The holes are drilled a hair out of line, so under a slight twist one pin jams before the others, and it can be nudged up until its cut reaches the seam and catches there; then the next one jams, and the next. A flawless lock would grip every pin at once and give nothing away. It is opened one small manufacturing mistake at a time.

László Bíró was a Hungarian newspaperman who noticed that the ink on the presses dried almost the moment it touched paper, and wanted a pen that could do the same. That ink was far too thick to run through a nib, so the pen he patented in 1938 ended in a tiny ball instead, turning in its socket, wetting itself on the way in and laying the ink down on the way out. In Britain his surname became the ordinary word for the thing, a biro, lower case. In Argentina, where he settled and started making them, it is a birome: Bíró, plus the first letters of Meyne, the friend who left Europe with him and went into business beside him. Plenty of inventors end up as a noun. Hardly any get to bring a friend along inside it.

An archerfish knocks insects off overhanging leaves with a jet of water, and to hit one it has to aim at a place where the insect doesn’t appear to be. Light bends as it crosses the surface, so from below everything above the water sits a little off, and the fish corrects for it, from steep angles and shallow ones. Researchers also report that it shapes the jet, so the back of the water travels faster than the front and catches up just short of the target, landing as one blob. Nobody taught it Snell’s law. Whatever it knows, it seems to know it the way most things are known before anyone writes them down: from the shots that missed.

When someone reads out a phone number, they group it their way, and you read it back yours: threes where they said twos, a pair where they ran four together. For a moment both of you are less sure of it, though not one digit has changed. The digits were never the trouble. A number is held by its rhythm more than its figures, and you have just handed it back in a different tune.

Since 1972 the world’s clocks have been given an extra second twenty-seven times, a 23:59:60 slipped in at the end of a day, so they wouldn’t run ahead of the Earth, which turns a touch slower than the atomic seconds we measure it in. In 2022 the people who keep time voted to stop doing it. One reason is that the planet has lately been turning a hair faster, and one day a second might need taking away instead, which no clock has ever done and a lot of software was never written to survive. So the plan is to let the clocks and the sky drift apart for a long while, perhaps by as much as a minute, and settle up much later. It is a very human way to handle a small, steady difference: not fixing it, just agreeing to look at it less often.

The Four Corners monument, where Utah, Colorado, Arizona and New Mexico meet, is not quite where the lines were meant to cross. The surveyors who set the corner in the 1800s missed by about eighteen hundred feet, which the National Geodetic Survey worked out in 2009 after the news had briefly reported it as two and a half miles and then had to correct itself. None of it moved the border. Once a marker has been set in the ground and everyone has agreed to it, the marker is the line, and all four states have long since written that into their laws. So the people who kneel on the plaque with a hand and a foot in each state are exactly right. The only thing that was ever wrong was the description it was built from.

An apron used to be a napron, from an old French word for a little tablecloth, in the same family as napkin. Somewhere in the late Middle Ages enough people heard “a napron” as “an apron” that the n slipped out of the noun and into the article, and it has stayed there since. The adder did the same thing; it was a nadder. The traffic ran the other way too: a nickname was an ekename, an extra name, until it picked up an n from the word next door. Nobody decided any of this. It happened because the words were said out loud, quickly, to people who were listening for the meaning and not for where one word ended and the next began.

When Joseph Bazalgette laid out London’s sewers in the 1850s and 60s, he worked out how wide each pipe would need to be for the most crowded streets he could imagine, and then, as the story is usually told, doubled it, on the grounds that they were only going to do this once. The Institution of Civil Engineers reckons the narrower pipes would have been overwhelmed by the 1960s. Nobody walking above them has ever thanked him for the extra width, and nobody could: the best kind of foresight leaves no trace that a decision was made, only that the drains still go. A good deal of what we inherit is probably like that, decided once, out of sight, by someone allowing for strangers they would never meet.

Climbing stairs in the dark, there is nearly always a moment when a foot goes up for one more step that isn’t there and stamps down onto the landing as if it had been tricked. Nothing was wrong with the stairs. Somewhere below thought a count was being kept, and nobody knew it was being kept until it came out one too many. It may be the only way most of us ever find out how carefully we were counting.

Nobody has ever watched a European eel being born. Aristotle decided they came out of the mud. Freud, as a young researcher, cut open hundreds of eels looking for testes and never found any. In the early 1900s a Danish biologist, Johannes Schmidt, went at it from the other end: he spent years trawling the Atlantic for eel larvae and noticed that the further west and south he caught them, the smaller they were, until the smallest of all turned up in the Sargasso Sea. That is still most of the evidence. No one has found an eel egg there or seen a pair spawning; eels have since been tracked heading that way, and the rest is inferred. It is how you find where a rumour started. You can’t hear the first telling, so you follow it back to the place where it is smallest.

For a long time, in the north, a hundred was a hundred and twenty. Old Norse hundrað counted twelve tens, so “two hundred” meant two hundred and forty, and anyone who needed the plain hundred we use now had to say which hundred they meant. The second half of the word, the -rað, meant reckoning, so the number carried its own instructions for counting folded up inside it. English kept the word and quietly let the extra twenty go. Nobody remembers agreeing to that, which is how most bargains with a word get made.

The hook on the end of a tape measure is loose, and a great many people have squeezed the rivets to fix it. It is loose on purpose. It slides by exactly its own thickness: hooked over the edge of a board, it pulls out, so the metal isn’t counted; pushed against a wall, it slides in, so the metal is. Either way the measurement starts from the right place. Tighten it and the tape becomes right one way and wrong the other, by about a sixteenth of an inch, quietly, for good. The rattle was the part doing the arithmetic.

Everyone has waved back at someone who was waving to the person behind them. The hand is already up by the time you understand, and there is no way to take a wave back, so on the way down it turns into something else: a stretch, a hand through the hair, a sudden need to check a watch you may not be wearing. Nobody has ever been fooled by this, including the person doing it. It isn’t really a disguise. It is a courtesy to the whole street, a way of saying: you saw nothing, and neither did I.

In 1904 Lizzie Magie patented a board game meant to show people what was wrong with landlords. The Landlord’s Game came with two sets of rules: in one, players grew rich by charging rent until everyone else was ruined; in the other, whenever anyone created wealth, every player was rewarded. You were supposed to play the first, feel how it went, and prefer the second. The first is the one that survived, as Monopoly, and in 1935 Parker Brothers bought her patent for $500. The game still teaches her lesson, every single time. Only to whoever is losing.

Point Roberts, Washington, is the tip of a peninsula that hangs a few miles below the 49th parallel, so when the border was ruled straight across the map it came out American and cut off, by land, from the rest of America. The town’s own school is small, so older children ride a bus north into Canada, along through the suburbs, and back south into the United States to reach school in Blaine: two international borders before first period, two more on the way home. Most people cross a border on holiday, with a passport and a little ceremony. These children cross it with homework, and probably have a better idea than any of us where it actually is.

The lyrebird that imitates a chainsaw, the one nearly everyone has seen on television, lived in a wildlife sanctuary. Another famous mimic, at Adelaide Zoo, picked up hammers and drills while the builders were in. As far as anyone has recorded, no wild lyrebird has ever been caught copying a chainsaw. A bird copies what it hears most days, and in the forest that is other birds. The captive ones were never telling us about the forest. They were telling us, very accurately, about the zoo.

At the end of a meeting there is nearly always one biscuit left on the plate. Everyone wanted it a little and nobody wanted it enough to be the one who took it, so it stays, and someone carries it back to the kitchen on its plate like a guest nobody asked to leave. It may be the only thing the whole room agreed on all afternoon, and they settled it without a word or a vote.

A kettle never takes the water’s temperature. Near the handle, at the bottom of a short tube that opens into the top of the jug, sits a small dished disc of two metals bonded together. While the water is merely hot, nothing reaches it. Once the water really boils, steam is pushed down the tube, warms the disc, and the disc snaps inside out with the click that opens the circuit. That is why a kettle still works on a mountain, where water boils below a hundred degrees: it was never waiting for a number, only for the water to start sending something up. It is a patient arrangement. The kettle doesn’t go and check. It waits to be told, by the one thing that can only arrive once the job is done.

There is no horse in a nightmare. The mare is Old English mære, a spirit that was believed to sit on a sleeper’s chest and press the breath out of them, and it has nothing to do with the mare in a field, whose name comes down a different road. In 1781 Henry Fuseli painted The Nightmare with the right creature squatting on the sleeping woman and, behind the curtain, a horse’s head looking in, probably as a joke. The joke has worn better than the word. Ask most people now what the mare in nightmare is, and they will tell you it’s the horse, the one that only came in to look.