50 Fun Facts About Signs and Symbols

Mr. Yuk, a green grimacing face, was put on US poison labels because children linked the skull and crossbones to what?

Pirates made the skull and crossbones look like fun to children, US poison-control groups feared, so the green, tongue-out Mr. Yuk was adopted for poison labels instead.

The three chasing arrows of the recycling symbol, drawn by 23-year-old student Gary Anderson, trace what shape?

A Möbius strip is what the arrows fold into; Anderson's entry won a 1970 contest run by the Container Corporation of America to mark the first Earth Day.

Why did the 1906 International Radiotelegraph Convention choose SOS as the distress call?

A distinctive Morse sequence is all it was; 'save our souls' and 'save our ship' were backronyms invented later, after the code had first appeared in German regulations of 1905.

The two parallel lines through the euro sign, unveiled by the European Commission in 1996, officially signify what?

Stability is the official reading of the double bar; Arthur Eisenmenger, once the EEC's chief graphic designer, claims he had the idea 25 years before the Commission's unveiling.

Which Swedish naturalist first used the Mars and Venus symbols to mark male and female flowers, in 1751?

Carl Linnaeus, sorting flowers by their stamens and pistils, was first to press the astronomers' planet signs into service for the sexes, and biology has kept them ever since.

Susan Kare lifted the ⌘ on Apple's Mac keyboards from a road sign used in Nordic countries to mark what?

Places of interest is what the looped square marks on Nordic roads; Kare found it in a symbol dictionary after Steve Jobs vetoed filling the Mac's menus with Apple logos.

The two-snake caduceus on US Army medical insignia is, in Greek myth, the staff carried by which god?

Hermes, god of trade and messengers, carries the caduceus; its adoption for US Army medical officers in 1902 spread the mix-up with the single-snake rod of Asclepius, medicine's older emblem.

The red and white barber's pole, with a basin-shaped top, recalls which medical service barbers once offered?

Bloodletting is the trade behind the stripes: the pole stood for the staff patients gripped to speed blood flow, and the basin held the blood, or the leeches.

Which engineer chose the @ sign in 1971 to split a user's name from a host in the first networked email?

Ray Tomlinson of BBN picked the little-used @ key, a mark that had spent centuries as an abbreviation for the arroba, a Spanish weight of about 25 pounds.

The % sign grew out of a looped scribal shorthand for a phrase in which language meaning 'for a hundred'?

Italian merchants' 'per cento' shrank to a looped 'pc', which by 1650 had become a horizontal fraction-like mark and then lost the 'per' entirely.

Gerald Holtom drew the circle-and-lines peace symbol in 1958 for an Aldermaston march by a British campaign for what?

Nuclear disarmament's initials N and D, as sent by flag semaphore, are superimposed in the design Holtom presented to the Direct Action Committee in February 1958.

Masahiro Hara, inventor of the QR code at Denso Wave in 1994, modelled its black-and-white squares on which board game?

Go's black and white counters inspired Hara's alternating squares, in a code built for labelling automobile parts.

The Bluetooth logo binds two runes for a Danish king's initials, taken from which runic alphabet?

Younger Futhark's Hagall (ᚼ) and Bjarkan (ᛒ) merge into one bind rune, a nod to the 10th-century king whose nickname the wireless standard borrowed.

Which artist's lithograph of a dove, made after World War II, turned the bird into a secular symbol of peace?

Pablo Picasso's Dove took an image early Christians had used, with the olive branch, and gave it a new life as a peace symbol in the years after the Second World War.

Harvey Ball drew the yellow smiley face in 1963 to lift morale after a merger at a Worcester firm in what business?

Life insurance was the trade: State Mutual Life Assurance Company wanted a little smile for buttons, desk cards and posters, and Ball, a freelance artist, drew one.

Charles Baldwin created the three-crescent biohazard symbol in 1966 for the containment products of which company?

Dow Chemical's Charles Baldwin, an environmental-health engineer, developed the symbol for the firm's containment products, and it was adopted worldwide.

The radiation trefoil was drawn in 1946 at the Radiation Laboratory of which university, originally in magenta?

Berkeley's Radiation Laboratory staff doodled it out in 1946, and the first signs were magenta on a blue background; the familiar yellow came later.

Under the UN's Globally Harmonized System, chemical hazard pictograms sit inside a frame of what shape and colour?

A red diamond frames each GHS pictogram on a white ground; a second, more colourful set of pictograms is used for transporting dangerous goods.

On the NFPA 704 hazard square posted at US chemical sites, what does the yellow quadrant rate?

Reactivity, or instability, is yellow on the right; red on top is flammability, blue on the left is health, and the white box holds special codes, a scheme credited to the Charlotte Fire Department after a 1959 fire.

The word 'clef', for the sign that opens a musical staff, is simply the French word for what?

Key is the French clef, and the name fits: the sign fixes one reference note on one line, unlocking every other line and space on the staff.

The treble clef, which curls around the second line of the staff, is a stylised form of which letter?

G is the letter the treble clef grew from, its curl circling the G above middle C; the bass clef is likewise a worn-down F and the alto clef a C.

In sheet music, 'D.S. al coda' sends the player back to which marking before the jump to the coda?

The segno, an S crossed by a diagonal stroke with two dots, is where dal segno restarts the passage, until 'To coda' jumps the player forward to the coda.

Flag semaphore, still taught to Scouts, began in 1866 as a hand-held version of which earlier signalling system?

Optical telegraph towers devised by Home Riggs Popham, later improved by Charles Pasley, were the model; the hand-flag version appeared in 1866 and the US Navy still uses it.

Which letter's maritime signal flag, a white-and-blue swallowtail, tells other vessels 'I have a diver down'?

Alpha, or Alfa, flies from diving support vessels that cannot move from their position and warns others to keep clear at slow speed; Oscar means man overboard.

The 'Blue Peter', hoisted when a ship is about to leave port, is the signal flag for which letter?

P, Papa, a blue flag bearing a white square, is flown in harbour to say all persons should report aboard because the vessel is about to proceed to sea.

Before Tacitus recorded a white flag of surrender in 109 CE, Roman armies gave up by doing what?

Holding shields above their heads was the Roman signal; the white flag's first recorded use is from China's Eastern Han dynasty, and Tacitus mentions one in 109 CE.

In motor racing, what does a black flag with an orange disc in its centre tell a driver to do?

Pit for a mechanical problem is the order: the car has serious trouble or loose bodywork that presents a risk to other competitors, so it is summoned in.

On the UK cover of the Beatles' album Help!, the four semaphore arm poses spell which letters instead of HELP?

NUJV is what the UK Parlophone sleeve spells; photographer Robert Freeman found the real letters ugly and rearranged the arms, and the US Capitol sleeve reads NVUJ.

Pluto's astronomical symbol, announced by its discoverers in 1930, is a monogram of which two letters?

P and L stand for Pluto but also for Percival Lowell, whose observatory began the search for a planet beyond Neptune that eventually turned up Pluto.

Jérôme Lalande designed a symbol for Uranus as a globe topped with the initial of which astronomer?

William Herschel, the planet's discoverer, was told by Lalande it was 'a globe surmounted by the first letter of your name', and French almanacs for a time called the planet Herschel.

Le Verrier, who predicted Neptune mathematically, proposed which symbol for it while falsely claiming official approval?

A trident, the sea god's weapon, was Le Verrier's pick, and he claimed the French Bureau des Longitudes had already approved both it and the name Neptune.

The star and crescent, now on Turkey's flag, was developed around 300 BC as the emblem of which Greek colony?

Byzantium, later Constantinople and then Istanbul, developed it; it then served Pontic king Mithridates VI and, centuries on, the Ottoman Empire, whose 1844 flag Turkey still flies.

The six-pointed Star of David became a distinctive emblem of Jewish communities in the 17th century in which city?

Prague's Jewish community adopted the hexagram, two overlapping equilateral triangles, as its own, though the shape appears as mere decoration in synagogues from antiquity.

The Ashoka Chakra at the centre of India's flag is a dharma wheel with how many spokes?

Twenty-four spokes turn on the Ashoka Chakra; Buddhist dharma wheels also come with 8 or 12, the eight commonly read as the Noble Eightfold Path.

An early circular ichthys, the fish emblem built from Greek letters, is carved into the marble ruins of which city?

Ephesus keeps the wheel-like carving; the five letters are an acrostic of 'Jesus Christ, God's Son, Saviour', which is why early Christians chose the fish.

Which Egyptian hieroglyph for 'life', a loop-topped cross, also spelled the sounds of the words for mirror and bouquet?

The ankh, or key of life, often appears in Egyptian art held by gods as a physical object standing for life or for life-giving air and water.

The swastika's name comes from a word meaning 'conducive to well-being' in which ancient language?

Sanskrit svastika names an ancient cross-cultural sign used by many religions across Eurasia, millennia before its 20th-century appropriation in Europe.

Which paragraph mark, nicknamed the 'blind P', did medieval rubricators paint in red to mark a new train of thought?

The pilcrow, ¶, survives as the paragraph symbol in editing software; its ancestor was a C for capitulum, 'little head', which once marked a new chapter.

Dutch and Afrikaans speakers call the @ sign by a name that means the tail of which animal?

Monkey tail, apenstaart in Dutch and aapstert in Afrikaans, is one of many animal names for @; Belarusians see a snail in it.

The ampersand, first seen in 1st-century Roman cursive, began as a scribal ligature of which two-letter Latin word?

Et, Latin for 'and', was written with its E and T joined in old Roman cursive, and in many italic ampersands the two letters are still plainly visible.

Chris Messina borrowed the # sign from IRC chat channels in 2007 to propose grouping posts on which platform?

Twitter got the idea in a single tweet, and Messina never tried to patent the hashtag, saying such things were 'born of the internet, and owned by no one'.

Which typewriter maker offered the interrobang, Martin Speckter's ‽, as a key on some of its 1968 models?

Remington put the mark on some typewriters in 1968, six years after Speckter coined it, having rejected 'exclamaquest' and 'exclarotive' for a name ending in printers' slang for the exclamation point.

Which Welsh mathematician introduced = in 1557, choosing parallel lines because 'no two things can be more equal'?

Robert Recorde's The Whetstone of Witte used 'a paire of paralleles, or Gemowe lines' to avoid repeating 'is equalle to', just one year before his death.

William Oughtred, who gave us the × sign in his 1631 Clavis Mathematicae, is also credited with inventing what?

The slide rule, about 1622, came from Oughtred sliding two of Edmund Gunter's logarithmic scales past each other; he also coined the 'sin' and 'cos' abbreviations.

The ISO 80000-2 standard says the ÷ sign 'should not be used' for division; which mark does it recommend instead?

The slash, formally the solidus, or a horizontal fraction bar, is the recommended way to write division; the colon is reserved for ratios, and ÷, first used by Johann Rahn in 1659, is formally deprecated.

Which Welsh mathematician first used the Greek letter π for the circle ratio in 1706, long before Euler popularised it?

William Jones's 1706 choice caught on only after Euler adopted it and, through his wide correspondence, the letter spread across Europe.

Shigetaka Kurita said his 1999 emoji drew on manga, Chinese characters, street signs and pictograms used for what?

Weather forecasts' pictograms fed into a set whose general-use emoji for sports, actions and weather are still traceable to Kurita's designs, each drawn in a single colour.

Apple's first iPhone emoji, added in November 2008, at first worked only with SIM cards from which country?

Japan's SoftBank SIM holders alone got the keyboard at first; Americans soon learned that downloading Japanese apps unlocked it, and the pressure to open it up grew.

The 🔰 emoji copies the shoshinsha mark, a yellow-and-green chevron that must be displayed on cars by whom?

Beginner drivers must display the chevron on their cars, and the emoji is one of several rooted in a single culture, alongside the deeply bowing businessman.

The wheelchair accessibility symbol began as a 1968 sketch by design student Susanne Koefoed, from which country?

Denmark's Koefoed drew a headless figure; Karl Montan's committee added a circle for a head so it read as a seated person rather than an empty chair.