Category: Computer History

CS4FN Advent – Day 22: stars and celestial navigation

Every day from the 1st to the 25th of December this blog will publish a Christmas Computing post, as part of our CS4FN Christmas Computing Advent Calendar. On the front of the calendar for each day is a festive cartoon which suggests the post’s theme – today’s is a star, so today’s post is about finding your way: navigation.

Follow that star…

 

In modern cities looking up at the night sky is perhaps not as dramatic as it might have been in the past, or in a place with less light pollution. For centuries people have used stars and the patterns they form to help them find their way.

GPS Orbital Navigator Satellite (DRAGONSat), photograph by NASA.

There are many ways our explorations of space have led to new technologies, though satellites have perhaps had the most obvious effect on our daily lives. Early uses were just for communication, allowing live news reports from the other side of the world, with networks that span the globe. More recently GPS – the Global Positioning System has led to new applications and now we generally just use our phones or satnav to point us in the right direction.

 

The very first computers

by Paul Curzon, QMUL. This post was first published on the CS4FN website.

Victorian engineer Charles Babbage designed, though never built the first mechanical computer. The first computers had actually existed for a long time before he had his idea, though. The British superiority at sea and ultimately the Empire was already dependent on them. They were used to calculate books of numbers that British sailors relied on to navigate the globe. The original meaning of the word computer was actually a person who did these calculations. The first computers were humans.

An American almanac from 1816. Image by Dave Esons from Pixabay

Babbage became interested in the idea of creating a mechanical computer in part because of computing work he did himself, calculating accurate versions of numbers needed for a special book: ‘The Nautical Almanac’. It was a book of astronomical tables, the result of an idea of Astronomer Royal, Nevil Maskelyne. It was the earliest way ships had to reliably work out their longitudinal (i.e., east-west) position at sea. Without them, to cross the Atlantic, you just set off and kept going until you hit land, just as Columbus did. The Nautical Almanac gave a way to work out how far west you were all the time.

Maskelyne’s idea was based on the fact that the angle from the moon’ to a person on the Earth and back to a star was the same at the same time wherever that person was looking from (as long as they could see both the star and moon at once). This angle was called the lunar distance.

The lunar distance could be used to work out where you were because as time passed its value changed but in a predictable way based on Newton’s Laws of motion applied to the planets. For a given place, Greenwich say, you could calculate what that lunar distance would be for different stars at any time in the future. This is essentially what the Almanac recorded.

Moon image by PollyDot from Pixabay

Now the time changes as you move East or West: Dawn gradually arrives later the further west you go, for example, as the Earth rotates the sun comes into view at different times round the planet). That is why we have different time zones. The time in the USA is hours behind that in Britain which itself is behind that in China. Now suppose you know your local time, which you can check regularly from the position of the sun or moon, and you know the lunar distance. You can look up in the Almanac the time in Greenwich that the lunar distance occurs and that gives you the current time in Greenwich. The greater the difference that time is to your local time, the further West (or East) you are. It is because Greenwich was used as the fixed point for working the lunar distances out, that we now use Greenwich Mean Time as UK time. The time in Greenwich was the one that mattered!

This was all wonderful. Sailors just had to take astronomical readings, do some fairly simple calculations and a look up in the Almanac to work out where they were. However, there was a big snag. it relied on all those numbers in the tables having been accurately calculated in advance. That took some serious computing power. Maskelyne therefore employed teams of human ‘computers’ across the country, paying them to do the calculations for him. These men and women were the first industrial computers.

Book of logarithms, image by sandid from Pixabay

Before pocket calculators were invented in the 1970s the easiest way to do calculations whether big multiplication, division, powers or square roots was to use logarithms (not to be confused with algorithm). The logarithm of a number is just the number of times you can divide it by 10 before you get to 1. Complicated calculations can be turned in to simple ones using logarithms. Therefore the equivalent of the pocket calculator was a book containing a table of logarithms. Log tables were the basis of all other calculations including maritime ones. Babbage himself became a human computer, doing calculations for the Nautical Almanac. He calculated the most accurate book of log tables then available for the British Admiralty.

The mechanical computer came about because Babbage was also interested in finding the most profitable ways to mechanise work in factories. He realised a machine could do more than weave cloth but might also do calculations. More to the point such a machine would be able to do them with a guaranteed accuracy, unlike people. He therefore spent his life designing and then trying to build such a machine. It was a revolutionary idea and while his design worked, the level of precision engineering needed was beyond what could be done. It was another hundred years before the first electronic computer was invented – again to replace human computers working in the national interest…but this time at Bletchley Park doing the calculations needed to crack the German military codes and so win the World War II.

 

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

 

 

Previous Advent Calendar posts

CS4FN Advent – Day 1 – Woolly jumpers, knitting and coding (1 December 2021)

 

CS4FN Advent – Day 2 – Pairs: mittens, gloves, pair programming, magic tricks (2 December 2021)

 

CS4FN Advent – Day 3 – woolly hat: warming versus cooling (3 December 2021)

 

CS4FN Advent – Day 4 – Ice skate: detecting neutrinos at the South Pole, figure-skating motion capture, Frozen and a puzzle (4 December 2021)

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle (5 December 2021)

 

CS4FN Advent – Day 6 – patterned bauble: tracing patterns in computing – printed circuit boards, spotting links and a puzzle for tourists (6 December 2021)

 

CS4FN Advent – Day 7 – Computing for the birds: dawn chorus, birds as data carriers and a Google April Fool (plus a puzzle!) (7 December 2021)

 

CS4FN Advent – Day 8: gifts, and wrapping – Tim Berners-Lee, black boxes and another computing puzzle (8 December 2021)

 

CS4FN Advent – Day 9: gingerbread man – computing and ‘food’ (cookies, spam!), and a puzzle (9 December 2021)

 

CS4FN Advent – Day 10: Holly, Ivy and Alexa – chatbots and the useful skill of file management. Plus win at noughts and crosses – (10 December 2021)

 

CS4FN Advent – Day 11: the proof of the pudding… mathematical proof (11 December 2021)

 

CS4FN Advent – Day 12: Computer Memory – Molecules and Memristors – (12 December 2021)

 

CS4FN Advent – Day 13: snowflakes – six-sided symmetry, hexahexaflexagons and finite state machines in computing (13 December 2021)

 

CS4FN Advent – Day 14 – Why is your internet so slow + a festive kriss-kross puzzle (14 December 2021)

 

CS4FN Advent – Day 15 – a candle: optical fibre, optical illusions (15 December 2021)

 

CS4FN Advent – Day 16: candy cane or walking aid: designing for everyone, human computer interaction (16 December 2021)

 

CS4FN Advent – Day 17: reindeer and pocket switching (17 December 2021)

 

CS4FN Advent – Day 18: cracker or hacker? Cyber security(18 December 2021)

 

CS4FN Advent – Day 19: jingle bells or warning bells? Avoiding computer scams (19 December 2021)

 

CS4FN Advent – Day 20: where’s it @? Gift tags and internet addresses (20 December 2021)

 

CS4FN Advent – Day 21: wreaths and rope memory – weave your own space age computer (21 December 2021)

 

 

CS4FN Advent – Day 22: stars and celestial navigation (22 December 2021) – this post

 

 

 

CS4FN Advent – Day 5 – snowman: analog hydraulic computers (aka water computers), digital compression, and a puzzle

This post is behind the 5th ‘door’ of the CS4FN Christmas Computing Advent Calendar – we’re publishing a computing-themed (and sometimes festive-themed) post every day until Christmas Day. Today’s picture is a snowman, and what’s a snowman made of but frozen water?

1. You can make a computer out of water!

1n 1936 Vladimir Lukyanov got creative with some pipes and pumps built a computer, called a water (or hydraulic) integrator, which could store water temporarily in some bits and pump water to other bits. The movement of water and where it ended up used the ‘simplicity of programming’ to show him the answer – a physical representation of some Very Hard Sums (sums, equations and calculations that are easier now thanks to much faster computers).

A simple and effective way of using water to show a mathematical relationship popped up on QI and the video below demonstrates Pythagoras’ Theorem rather nicely.

In 1939 Lukyanov published an article about his analog hydraulic computer for the (‘Otdeleniye Technicheskikh Nauk’ or ‘Отделение технических наук’ in Russian which means Section for Technical Scientific Works although these days we’d probably say Department of Engineering Sciences) and in 1955 this was translated by the Massachusetts Institute of Technology (MIT) for the US army’s “Arctic Construction and Frost Effects Laboratory”. You can see a copy of his translated ‘Hydraulic Apparatus for Engineering Computations‘ at the Internet Archive.

In a rather pleasing coincidence for this blog post (that you might think was by design rather than just good fortune) this device was actually put to work by the US Army to study the freezing and thawing not of snowmen but of soil (ie, the ground). It’s particularly useful if you’re building and maintaining a military airfield (or even just roads) to know how well the concrete runway will survive changes in weather (and how well your aircraft’s wheels will survive after meeting it).

For a modern take on the ‘hydrodynamic calculating machine’ aka water computer see this video from science communicator Steve Mould in which he creates a computer that can do some simple additions.

 

2. The puzzle of digital compression

Our snowman’s been sitting around for a while and his ice has probably become a bit compacted, so he might be taking up less space (or he might have melted). Compression is a technique computer scientists use to make big data files smaller.

Big files take a long time to transfer from one place to another. The more data the longer it takes, and the more memory is needed to store the information. Compressing the files saves space. Data on computers is stored as long sequences of characters – ultimately as binary 1s and 0s. The idea with compression is that we use an algorithm to change the way the information is represented so that fewer characters are needed to store exactly the same information.

That involves using special codes. Each common word or phrase is replaced by a shorter sequence of symbols. A long file can be made much shorter if it has lots of similar sequences, just as the message below has been shortened. A second algorithm can then be used to get the original back. We’ve turned the idea into a puzzle that involves pattern matching patterns from the code book. Can you work out what the original message was? (Answer tomorrow).

The code: NG1 AMH5 IBEC2 84F6JKO 7JDLC93 (clue: Spooky apparitions are about to appear on Christmas Eve)

The code book (match the letter or number to the word it codes for).

3. Answer to yesterday’s puzzle

The creation of this post was funded by UKRI, through grant EP/K040251/2 held by Professor Ursula Martin, and forms part of a broader project on the development and impact of computing.

Letters from the Victorian Smog: Braille: binary, bits & bytes

by Paul Curzon, Queen Mary University of London

Reading Braille image by Myriams-Fotos from Pixabay

We take for granted that computers use binary: to represent numbers, letters, or more complicated things like music and pictures…any kind of information.That was something Ada Lovelace realised very early on. Binary wasn’t invented for computers though. Its first modern use as a way to represent letters was actually invented in the first half of the 19th century. It is still used today: Braille.

Braille is named after its inventor, Louis Braille. He was born 6 years before Ada though they probably never met as he lived in France. He was blinded as a child in an accident and invented the first version of Braille when he was only 15 in 1824 as a way for blind people to read. What he came up with was a representation for letters that a blind person could read by touch.

Choosing a representation for the job is one of the most important parts of computational thinking. It really just means deciding how information is going to be recorded. Binary gives ways of representing any kind of information that is easy for computers to process. The idea is just that you create codes to represent things made up of only two different characters: 1 and 0. For example, you might decide that the binary for the letter ‘p’ was: 01110000. For the letter ‘c’ on the other hand you might use the code, 01100011. The capital letters, ‘P’ and ‘C’ would have completely different codes again. This is a good representation for computers to use as the 1’s and 0’s can themselves be represented by high and low voltages in electrical circuits, or switches being on or off.

The first representation Louis Braille chose wasn’t great though. It had dots, dashes and blanks – a three symbol code rather than the two of binary. It was hard to tell the difference between the dots and dashes by touch, so in 1837 he changed the representation – switching to a code of dots and blanks.

He had invented the first modern form of writing based on binary.

Braille works in the same way as modern binary representations for letters. It uses collections of raised dots (1s) and no dots (0s) to represent them. Each gives a bit of information in computer science terms. To make the bits easier to touch they’re grouped into pairs. To represent all the letters of the alphabet (and more) you just need 3 pairs as that gives 64 distinct patterns. Modern Braille actually has an extra row of dots giving 256 dot/no dot combinations in the 8 positions so that many other special characters can be represented. Representing characters using 8 bits in this way is exactly the equivalent of the computer byte.

Modern computers use a standardised code, called Unicode. It gives an agreed code for referring to the characters in pretty well every language ever invented including Klingon! There is also a Unicode representation for Braille using a different code to Braille itself. It is used to allow letters to be displayed as Braille on computers! Because all computers using Unicode agree on the representations of all the different alphabets, characters and symbols they use, they can more easily work together. Agreeing the code means that it is easy to move data from one program to another.

The 1830s were an exciting time to be a computer scientist! This was around the time Charles Babbage met Ada Lovelace and they started to work together on the analytical engine. The ideas that formed the foundation of computer science must have been in the air, or at least in the Victorian smog.

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Further reading

This post was first published on CS4FN and also appears on page 7 of Issue 20 of the CS4FN magazine. You can download a free PDF copy of the magazine here as well as all of our previous magazines and booklets, at our free downloads site.

The RNIB has guidance for sighted people who might be producing Braille texts for blind people, about how to use Braille on a computer and get it ready for correct printing.

This History of Braille article also references an earlier ‘Night Writing’ system developed by Charles Barbier to allow French soldiers in the 1800s to read military messages without using a lamp (which gave away their position, putting them at risk). Barbier’s system inspired Braille to create his.

A different way of representing letters is Morse Code which is a series of audible short and long sounds that was used to communicate messages very rapidly via telegraphy.

Find out about Abraham Louis Breguet’s ‘Tactful Watch‘ that let people work out what time it was by feel, instead of rudely looking at their watch while in company.

Ada Lovelace: Visionary

Cover of Issue 20 of CS4FN, celebrating Ada Lovelace

By Paul Curzon, Queen Mary University of London

It is 1843, Queen Victoria is on the British throne. The industrial revolution has transformed the country. Steam, cogs and iron rule. The first computers won’t be successfully built for a hundred years. Through the noise and grime one woman sees the future. A digital future that is only just being realised.

Ada Lovelace is often said to be the first programmer. She wrote programs for a designed, but yet to be built, computer called the Analytical Engine. She was something much more important than a programmer, though. She was the first truly visionary person to see the real potential of computers. She saw they would one day be creative.

Charles Babbage had come up with the idea of the Analytical Engine – how to make a machine that could do calculations so we wouldn’t need to do it by hand. It would be another century before his ideas could be realised and the first computer was actually built. As he tried to get the money and build the computer, he needed someone to help write the programs to control it – the instructions that would tell it how to do calculations. That’s where Ada came in. They worked together to try and realise their joint dream, jointly working out how to program.

Ada also wrote “The Analytical Engine has no pretensions to originate anything.” So how does that fit with her belief that computers could be creative? Read on and see if you can unscramble the paradox.

Ada was a mathematician with a creative flair and while Charles had come up with the innovative idea of the Analytical Engine itself, he didn’t see beyond his original idea of the computer as a calculator, she saw that they could do much more than that.

The key innovation behind her idea was that the numbers could stand for more than just quantities in calculations. They could represent anything – music for example. Today when we talk of things being digital – digital music, digital cameras, digital television, all we really mean is that a song, a picture, a film can all be stored as long strings of numbers. All we need is to agree a code of what the numbers mean – a note, a colour, a line. Once that is decided we can write computer programs to manipulate them, to store them, to transmit them over networks. Out of that idea comes the whole of our digital world.

Ada saw even further though. She combined maths with a creative flair and so she realised that not only could they store and play music they could also potentially create it – they could be composers. She foresaw the whole idea of machines being creative. She wasn’t just the first programmer, she was the first truly creative programmer.

This article was originally published at the CS4FN website, along with lots of other articles about Ada Lovelace. We also have a special Ada Lovelace-themed issue of the CS4FN magazine which you can download as a PDF (click picture below).

See also: The very first computers and Ada Lovelace Day (2nd Tuesday of October). Help yourself to our Women in Computing posters PDF (or sign up to get FREE copies posted to your school (UK-based only, please).

 

Emoticons and Emotions

Emoticons are a simple and easily understandable way to express emotions in writing using letters and punctuation without any special pictures, but why might Japanese emoticons be better than western ones? And can we really trust expressions to tell us about emotions anyway?

African woman smiling Image by Tri Le from Pixabay

The trouble with early online message board messages, email and text messages was that it was always more difficult to express subtleties, including intended emotions, than if talking to someone face to face. Jokes were often assumed to be serious and flame wars were the result. So when in 1982 Carnegie Mellon Professor Scott Fahlman suggested the use of the smiley : – ) to indicate a joke in message board messages, a step forward in global peace was probably made. He also suggested that since posts more often than not seemed to be intended as jokes then a sad face : – ( would be more useful to explicitly indicate anything that wasn’t a joke.

He wasn’t actually the first to use punctuation characters to indicate emotions though. The earliest apparently recorded use is in a poem in 1648 by Robert Herrick, an English poet in his poem “To Fortune”.

Tumble me down, and I will sit
Upon my ruins, (smiling yet:)

Whether this was intentional or not is disputed, as punctuation wasn’t consistently used then. Perhaps the poet intended it, perhaps it was just a coincidentall printing error, or perhaps it was a joke inserted by the printers. Either way it is certainly an appropriate use (why not write your own emoticon poem!)

You might think that everyone uses the same emoticons you are familiar with but different cultures use them in different ways. Westerners follow Fahlman’s suggestion putting them on their side. In Japan by contrast they sit the right way up and crucially the emotion is all in the eyes not the mouth which is represented by an underscore. In this style, happiness can be given by (^_^) and T or ; as an indication of crying, can be used for sadness: (T_T) or (;_;). In South Korea, the Korean alphabet is used so a different character set of letter are available (though their symbols are the right way up as with the Japanese version).

Automatically understanding people’s emotions is an important area of research, called sentiment analysis, whether analysing text, faces or other aspects that can be captured. It is amongst other things important for marketeers and advertisers to work out whether people like their products or what issues matter most to people in elections, so it is big business. Anyone who truly cracks it will be rich.

So in reality is the western version or the Eastern version more accurate: are emotions better detected in the shape of the mouth or the eyes? With a smile at least, it turns out that the eyes really give away whether someone is happy or not, not the mouth. When people put on a fake smile their mouth does curve just as with a natural smile. The difference between fake and genuine smiles that really shows if the person is happy is in the eyes. A genuine smile is called a Duchenne smile after Duchenne de Boulogne who in 1862 showed that when people find something actually funny the smile affects the muscles in their eyes. It causes a tell-tale crow’s foot pattern in the skin at the sides of the eyes. Some people can fake a Duchenne too though, so even that is not totally reliable.

As emoticons hint, because emotions are indicated in the eyes as much as in the mouth, sentiment analysis of emotions based on faces needs to focus on the whole face, not just the mouth. However, all may not be what it seems as other research shows that most of the time people do not actually smile at all when genuinely happy. Just like emoticons facial expressions are just a way we tell other people what we want them to think our emotions are, not necessarily our actual emotions. Expressions are not a window into our souls, but a pragmatic way to communicate important information. They probably evolved for the same reason emoticons were invented, to avoid pointless fights. Researchers trying to create software that works out what we really feel, may have their work cut out if their life’s work is to make them genuinely happy.

     ( O . O )
         0

– Paul Curzon, Queen Mary University of London, Summer 2021

The computer vs the casino: Wearable tech cheating

What happened when a legend of computer science took on the Las Vegas casinos? The answer, surprisingly, was the birth of wearable computing.

There have always been people looking to beat the system, to get that little bit extra of the odds going their way to allow them to clean up at the casino. Over the years maths and technology have been used, from a hidden mechanical arm up your sleeve allowing you to swap cards, to the more cerebral card counting. In the latter, a player remembers a running total of the cards played so they can estimate when high value cards will be dealt. One popular game to try and cheat was Roulette.

A spin of the wheel

Roulette, which comes from the French word ‘little wheel’, involves a dish containing a circular rotating part marked into red and black numbers. A simple version of the game was developed by the French mathematician, Pascal, and it evolved over the centuries to become a popular betting game. The central disc is spun and as it rotates a small ball is thrown into the dish. Players bet on the number that the ball will eventually stop at. The game is based on probability, but like most games there is a house advantage: the probabilities mean that the casino will tend to win more money than it loses.

Gamblers tried to work out betting strategies to win, but the random nature of where the ball stops thwarted them. In fact, the pattern of numbers produced from multiple roulette spins was so random that mathematicians and scientists have used these numbers as a random-number generator. Methods using them are even called Monte Carlo methods after the famous casino town. They are ways to calculate difficult mathematical functions by taking thousands of random samples of their value at different random places.

A mathematical system of betting wasn’t going to work to beat the game, but there was one possible weakness to be exploited: the person who ran the game and threw the ball into the wheel, the croupier.

No more bets please

There is a natural human instinct to spin the wheel and throw the ball in a consistent pattern. Each croupier who has played thousands of games has a slight bias in the speed and force with which they spin the wheel and throw the ball in. If you could just see where the wheel was when the spin started and the ball went in, you could use the short time before betting was suspended to make a rough guess of the area where the ball was more likely to land, giving you an edge. This is called ‘clocking the wheel’, but it requires great skill. You have to watch many games with the same croupier to gain a tiny chance of working out where their ball will go. This isn’t cheating in the same way as physically tampering with the wheel with weights and magnets (which is illegal), it is the skill of the gambler’s observation that gives the edge. Casinos became aware of it, so frequently changed the croupier on each game, so the players couldn’t watch long enough to work out the pattern. But if there was some technological way to work this out quickly perhaps the game could be beaten.

Blackjack and back room

Enter Ed Thorpe, in the 1950s, a graduate student in physics at MIT. Along with his interest in physics he had a love of gambling. Using his access to one of the world’s few room filling IBM computers at the university he was able to run the probabilities in card games and using this wrote a scientific paper on a method to win at Blackjack. This paper brought him to the attention of Claude Shannon, the famous and rather eccentric father of information theory. Shannon loved to invent things: the flame throwing trumpet, the insult machine and other weird and wonderful devices filled the basement workshop of his home. It was there that he and Ed decided to try and take on the casinos at Roulette and built arguably the first wearable computer.

Sounds like a win

The device comprised a pressure switch hidden in a shoe. When the ball was spun and passed a fixed point on the wheel, the wearer pressed the switch. A computer timer, strapped to the wrist, started and was used to track the progress of the ball as it passed around the wheel, using technology in place of human skill to clock the wheel. A series of musical tones told the person using the device where the ball would stop, each tone represented a separate part of the wheel. They tested the device in secret and found that using it gave them a 44% increased chance of correctly predicting the winning numbers. They decided to try it for real … and it worked! However, the fine wires that connected the computer to the earpiece kept breaking, so they gave up after winning only a few dollars. The device, though very simple and for a single purpose, is in the computing museum at MIT. The inventors eventually published the detail in a scientific paper called “The Invention of the First Wearable Computer,” in 1998.

The long arm of the law reaches out

Others followed with similar systems built into shoes, developing more computers and software to help cheat at Blackjack too, but by the mid 1980’s the casino authorities became wise to this way to win, so new laws were introduced to prevent the use of technology to give unfair advantages in casino games. It definitely is now cheating. If you look at the rules for casinos today they specifically exclude the use of mobile phones at the table, for example, just in case your phone is using some clever app to scam the casinos.

From its rather strange beginning, wearable computing has spun out into new areas and applications, and quite where it will go next is anybody’s bet.

– Peter W. McOwan, Queen Mary University of London, Autumn 2018

The very first computers

A head with numbers circling round and the globe in the middleVictorian engineer Charles Babbage designed, though never built the first mechanical computer. The first computers had actually existed for a long time before he had his idea, though. The British superiority at sea and ultimately the Empire was already dependent on them. They were used to calculate books of numbers that British sailors relied on to navigate the globe. The original meaning of the word computer was actually a person who did these calculations. The first computers were humans.

Babbage became interested in the idea of creating a mechanical computer in part because of computing work he did himself, calculating accurate versions of numbers needed for a special book: ‘The Nautical Almanac’. It was a book of astronomical tables, the result of an idea of Astronomer Royal, Nevil Maskelyne. It was the earliest way ships had to reliably work out their longitudinal (i.e., east-west) position at sea. Without them, to cross the Atlantic, you just set off and kept going until you hit land, just as Columbus did. The Nautical Almanac gave a way to work out how far west you were all the time.

Maskelyne’s idea was based on the fact that the angle from the moon’ to a person on the Earth and back to a star was the same at the same time wherever that person was looking from (as long as they could see both the star and moon at once). This angle was called the lunar distance.

The lunar distance could be used to work out where you were because as time passed its value changed but in a predictable way based on Newton’s Laws of motion applied to the planets. For a given place, Greenwich say, you could calculate what that lunar distance would be for different stars at any time in the future. This is essentially what the Almanac recorded.

Now the time changes as you move East or West: Dawn gradually arrives later the further west you go, for example, as the Earth rotates the sun comes into view at different times round the planet). That is why we have different time zones. The time in the USA is hours behind that in Britain which itself is behind that in China. Now suppose you know your local time, which you can check regularly from the position of the sun or moon, and you know the lunar distance. You can look up in the Almanac the time in Greenwich that the lunar distance occurs and that gives you the current time in Greenwich. The greater the difference that time is to your local time, the further West (or East) you are. It is because Greenwich was used as the fixed point for working the lunar distances out, that we now use Greenwich Mean Time as UK time. The time in Greenwich was the one that mattered!

This was all wonderful. Sailors just had to take astronomical readings, do some fairly simple calculations and a look up in the Almanac to work out where they were. However, there was a big snag. it relied on all those numbers in the tables having been accurately calculated in advance. That took some serious computing power. Maskelyne therefore employed teams of human ‘computers’ across the country, paying them to do the calculations for him. These men and women were the first industrial computers.

Before pocket calculators were invented in the 1970s the easiest way to do calculations whether big multiplication, division, powers or square roots was to use logarithms. The logarithm of a number is just the number of times you can divide it by 10 before you get to 1. Complicated calculations can be turned in to simple ones using logarithms. Therefore the equivalent of the pocket calculator was a book containing a table of logarithms. Log tables were the basis of all other calculations including maritime ones. Babbage himself became a human computer, doing calculations for the Nautical Almanac. He calculated the most accurate book of log tables then available for the British Admiralty.

The mechanical computer came about because Babbage was also interested in finding the most profitable ways to mechanise work in factories. He realised a machine could do more than weave cloth but might also do calculations. More to the point such a machine would be able to do them with a guaranteed accuracy, unlike people. He therefore spent his life designing and then trying to build such a machine. It was a revolutionary idea and while his design worked, the level of precision engineering needed was beyond what could be done. It was another hundred years before the first electronic computer was invented – again to replace human computers working in the national interest…but this time at Bletchley Park doing the calculations needed to crack the German military codes and so win the World War II.

More on …

HMS Belfast: destroying the destroyer

by Paul Curzon, Queen Mary University of London

HMS Belfast

On the South Bank of the Thames in the centre of London lies the HMSBelfast. Now a museum ship, it once took part in one of the most significant sea battles of the Second World War. It fought the Scharnhorst in the last great sea battle based on the power of great guns. The Belfast needed more than just brilliant naval tactics to stand a chance. It needed help from computer science and electronic engineering too. In fact, without some brilliant computer science the battle would never have been fought in the first place. It came about because of the work of the code crackers at Bletchley Park.

Getting supplies across the Atlantic and then round to Russia was critical to both the British and Russian’s survival. By 1943 the threat of submarines had been countered. The battleship Tirpitz had also been disabled. However, the formidable battle cruiser Scharnhorst was left and it was the scourge of the Allied convoys. It sank 11 supply ships in one operation early in 1941. In another, it destroyed a weather station on Spitzbergen island that the Allies used to decide when convoys should set off.

By Christmas 1943 something had to be done about the Scharnhorst, but how to catch it, never mind stop it? A trap was needed. A pair of convoys going to and from Russia were a potential bait. The Nazis knew the target was there for the taking: the Scharnhorst was in a nearby port. Would they take that bait though, and how could the British battle ships be in the right place at the right time to not only stop it, but destroy it?

The Allies had an ace up their sleeve. Computer Science. By this point in the war a top secret team at Bletchley Park had worked out how to crack the Enigma encryption machine that was used to send coded messages by the German Navy. It was always easy to listen in to radio broadcasts, you just needed receivers in the right places, but if the messages were in code that didn’t help. You had to crack the day’s code to know what they were saying. Based on an improved approach, originally worked out by Polish mathematicians, the Brits could do it using special machines that were precursors to the first electronic computers. They intercepted messages that told them that Scharnhorst was preparing to leave. It was taking the bait.

The British had two groups of ships. The Belfast, the Norfolk and the Sheffield were coming from Russia protecting the returning convoy. The HMS Duke of York was tracking the new convoy heading to Russia. Both were keeping their distance so the convoys looked unprotected. They needed to know when and where the Scharnhorst would attack. Bletchley Park were listening in to everything though, and doing it so well they were reading the messages almost as soon as the Germans. At 2am on Boxing Day morning the Belfast got the message from Admiralty Head quarters that SCHARNHORST PROBABLY SAILED AT 1800 25 DECEMBER. A further radio signal from the Scharnhorst asking for a weather report allowed the spies to work out exactly where the ship was by picking up the signal from different listening stations and triangulating: drawing a line on a map from each station in the direction the radio signal came from. The point they meet is the ship’s location. This is an example of meta-data (information about a message rather than the message itself) giving vital information away. The spies had done their job. It was enough to tell Vice Admiral Burnett on the Belfast where the Scharnhorst was aiming to attack the convoys. They could lie in wait. At this point, electronic engineering mattered. The Belfast had better radar than the Scharnhorst. They detected its approach without the Scharnhorst having any idea they were there. The first the Captain of the Scharnhorst knew was when they were hit by shells from the Norfolk. The Belfast ended up out of position at the critical point though and couldn’t join in. The faster Scharnhorst turned tail and ran. The Brits had had their chance and blown it!

Burnett now needed luck and intuition. He guessed the Scharnhorst would try another attack on the convoy. They took up a new waiting position rather than actively trying to find the Scharnhorst as others wanted them to do. By midday the radar picked it up again. The trap was reset, though this time the initial surprise was lost. An all out battle began, with radar helping once again, this time as a way to aim shells even when the enemy wasn’t in sight. Having failed to reach the convoy undetected a second time the Scharnhorst retreated as the battle continued. What they didn’t know was that they were retreating deeper into the trap: heading directly towards the waiting Duke of York. The chasing Belfast stopped firing and dropped back, making the Scharnhorst crew think they were safe. In fact, they were still being followed and tracked by radar once more, though only by the Belfast as the other ships had actually been partially disabled. Had the Scharnhorst known, they could have just stopped and taken out the Belfast. After several hours of silent shadowing, the Belfast picked up the Duke of York on the radar, and were able to communicate with them. The Scharnhorst’s radar had been crippled in the battle and thought it was alone.

The Belfast fired shells that lit up the sky behind the Scharnhorst as seen from the Duke of York, then largely watched the battle. Luck was on their side: the Scharnhorst was crippled and then sunk by torpedoes. Over a thousand German sailors sadly died. The crew of the Belfast were well aware that it could just as easily have been them, sealed in to a giant metal coffin, as it sank, and so held a memorial for the dead Germans afterwards.

The Belfast didn’t fire the torpedoes that finally sank the Scharnhorst and was not the key player in the final battle. However, it was the one that was in the right place to save the convoy, thanks to the Enigma decrypts combined with the Vice Admiral’s intuition. It was also the one that pushed the Scharnhorst into the deadly trap, with its superior radar then giving it the advantage.

It is easy to under-estimate the importance of the Bletchley Park team to the war, but they repeatedly made the difference, as with the Scharnhorst, making Allied commanders look amazing. It is much easier to be amazing when you know everything the other side says! The Scharnhorst is just one example of how Computer Science and Electronic Engineering help win wars, and here, in the long run at least, save lives. Today having secure systems matters to everyone not just to those waging war. We rely on them for our bank system, our elections, as well as for our everyday privacy, whether from hacking newspapers or keeping our health records secret from ruthless companies wanting to exploit us. Cyber security matters.

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Who invented Morse code?

by Paul Curzon, Queen Mary University of London

Morse code tapper: www.istock.com 877875

Who invented Morse code? Silly question, surely! Samuel Morse, of course. He is one of the most celebrated inventors on the planet as a result. Morse code helped revolutionise global communications. It was part of the reason the telegraph made fast, world-wide communication a practical reality. Morse did invent a code to use for the telegraph, but not Morse code. His code was, by comparison, a poor, inflexible solution. He was a great businessman, focussed on making his dream a reality, but perhaps not so good at computational thinking! The code that bears his name was largely invented by his partner Alfred Vail.

Samuel Morse was originally a painter. However, his life changed when his wife died suddenly. He was away doing a portrait commission at the time. On hearing of his wife’s illness he rushed home, but the message, delivered by a horse rider had taken too long to reach him and she died and was buried before he got there. He dedicated his life to giving the world a better way of communicating as a result. Several different people were working on the idea of a way to send messages by electricity over wires, but no one had really come up with a usable, practical system. The physics had largely been sorted, but the engineering was still lacking.

Morse came up with a basic version of an electrical telegraph system and he demonstrated it. Alfred Vail saw the demonstration and persuaded Morse to take him on as a partner. His father built a famous ironworks, and so he had worked as a machinist. He improved Morse’s system enormously including making the tapping machine used to send messages.

He wasn’t just good at engineering though. He was good at computational thinking, so he also worked on the code used for sending messages. Having a machine that can send taps down a wire is no use unless you can also invent a simple, easy to use algorithm that turns words into those taps, and back again once it arrives. Morse came up with a code based on words not letters. It was a variation of the system already used by semaphore operators. It involved a code book: essentially a list of words. Each word in the book was given a number. A second code turned numbers in to taps – in to dots and dashes. The trouble with this system is it is not very general. If the word you want to send isn’t in the code book you are stuffed! To cover every possibility it has to be the size of a dictionary, with every word numbered. But that would make it very slow to use. Vail came up with a version where the dots and dashes represented letters instead of numbers, allowing any message to be sent letter by letter.

He also realised that some letters are more common than others. He therefore included the results of what we now call “frequency analysis” to make the system faster, working out the order of letters based on how common they are. He found a simple way to do it. He went to his local newspaper offices! To print a page of text, printing presses used metal letters called movable type. Each page was built up out of the individual metal letters slotted in to place. Vail realised that the more common a letter was, the more often it appeared on any page, and the more metal versions the newspaper office would therefore need if they wasn’t to keep running out of the right letters before the page was done. He therefore counted how many of each “movable type” letter the newspaper printers had in their trays. He gave the letters that were most common the shortest codes. So E, for example, is just a single dot as it is the most common letter in American English. T, which is also common, is a single dash. It is this kind of attention to detail that made Morse code so successful. Vail was really good at computational thinking!

Morse and Vail worked really well as a team, though Morse then took all the credit because the original idea to solve the problem had been his, and their agreement meant the main rights were with Morse. They almost certainly worked together to some extent on everything to do with the telegraph. It is the small details that meant their version of the telegraph was the one that took over the world though and that was largely down to Vail. Morse maybe the famous one but the invention of the telegraph needed them both working together.

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