The Way Things Work Now

SENDING BITS WI-FI CONNECTION COMPUTER NETWORKS LAPTOP Most homes have a type of computer network called a LAN (Local Area Network), which enables computers and other digital devices to connect to one another and to the Internet. Each device can send and receive millions of bits every second, along wired links called ethernet cables, or wirelessly through the air, via Wi-Fi. Every device can be identified by an address – and at the heart of the network is a device called a router, which ensures that the network traffic reaches the correct destination. MEDIA PLAYER NETWORK ADDRESSES It is not only computers The router assigns an Internet Protocol, or IP, address to that can connect to a local every device on the network, including itself. An IP address network. A media player is normally made up of between four and eight numbers – can play music, photos for example, 192.168.0.12. When one device needs to send and movies stored on some pieces of information to another, it sends a request to other connected devices, the router labelled with the destination IP address. such as a desktop computer at the office. TELEPHONE LINE, OPTICAL FIBRE OR CABLE CONNECTION TABLET BREAKING IT DOWN Information on a network travels in chunks, each several thousand bits long, called packets. This enables the network to work more efficiently than if it was sending large files in one go. Every packet contains the IP addresses of both the source and destination devices. The destination device assembles the packets to reproduce the original information. WI-FI CONNECTION WI-FI ROUTER The most common way for networked devices to communicate with the router in a LAN is by Wi-Fi, which carries streams of bits in a similar way to digital radio (see p.242). DESKTOP WI-FI COMPUTER CONNECTION MEDIA SERVER ROUTER The desktop computer’s hard disk The router controls the traffic on the LAN, but or SSD (see pp.334-5) holds it also acts as a gateway to the Internet, which is movies, music and images that a vast network of interconnected networks. The can be streamed via the router router has a public IP address as well as its local to the media player and other (private) IP address, and can forward traffic to devices connected to the LAN. any device on any network in the world. Traffic to other networks on the Internet passes out of SMARTPHONE the house along telephone lines, cable TV cables or optical fibres. The router keeps track of any packets it sends out from devices on its own network, so that it knows where to forward any packets it receives from the Internet. [349]

WI-FI CONNECTS MODEM LAPTOP TO ROUTER In most networks, the router (see p.349) is combined with another device, called a modem, ROUTER PASSES which allows the local area network to be E-MAIL MESSAGE TO connected to the rest of the Internet. “Modem” TELEPHONE LINE is short for modulator-demodulator. It converts, E-MAIL or modulates, outgoing traffic from the LAN into a form that can be sent on telephone This user is sending an e-mail to friends overseas wires, cable TV cables or optical fibres (see (follow the yellow arrows tracking its route). The bits that make up the message are stored on a mail server pp.236-7) – and it demodulates incoming at the recipient’s ISP until they log in and retrieve it. traffic, converting it back into a form that can be passed on to devices LEASED LINE on the LAN. Some large businesses have LOCAL direct connections to ISPs via TELEPHONE high-capacity, high-speed fibre- EXCHANGE optic cables called leased lines. MAMMOTH INTERNET SERVICE PROVIDER CORPORATION The ISP gives access to the Internet, but also holds websites, e-mails and other data that can be accessed from anywhere on the Internet. MOBILE INTERNET ACCESS ISP INTERNET Mobile devices, such as smartphones, BACKBONE connect through to the mobile data network by exchanging radio signals ISP with antennas on towers, which connect to a local exchange or EXCHANGE specialized mobile exhanges. MOBILE TOWER HOME AUTOMATION LOCAL ROADSIDE CABINET ROUTES This user has an app on their smartphone CABLE INTERNET that controls the heating system at home SIGNALS TO ISP (follow the green arrows). The thermostat is connected to the home’s LAN and can CABLE COMPANY’S send temperature details as well as receive commands. LOCAL CONTROL CENTRE CONNECTS TO ISP SMARTPHONE ROUTER BROWSING THE WEB RECEIVES TEMPERATURE TABLET ACCESSES This user is using their tablet to access READING FROM WORLD WIDE WEB a web page (see pp.352-3) stored on a THERMOSTAT computer called a web server. The request goes via the user’s ISP and is routed to the web server, which is at another ISP. The web server sends the web page back to the tablet (follow the blue arrows). [350]

INTERNET RETRIEVING E-MAIL MESSAGE People use the global communications system known as the Internet for staying in touch with friends and UNDERSEA LINK family, keeping informed and entertained, shopping and banking – all in the form of millions of bits passing Internet traffic between countries between interconnected computer networks. Network separated by sea mostly travels as traffic speeding across the Internet relies on a backbone pulses of laser light along fibre-optic of cables containing bundles of optical fibres stretching cables. Deepsea cables are only as thick across and between countries. In homes, schools and as a finger, but in shallow waters they businesses, devices connected to local area networks have extra layers of protective casing (LANs, see p.349) gain access to the Internet through in case they get snagged by anchors companies called Internet Service Providers (ISPs). The and fishing nets. connection to an ISP can take several different forms, and normally involves a local telephone exchange. UNDERSEA CABLE INTERNET BACKBONE Stretching across countries and between countries are fibre- optic cables, each containing a bundle of individual fibres that can carry tens of billions of bits per second. Made of flexible, transparent glass, each fibre is not much thicker than a human hair. Connected into the Internet backbone of fibre-optic cables are powerful core routers, which direct vast numbers of bits towards their destination. CORE ROUTER MOBILE RADIO TOWER SIGNALS ISP EXCHANGE ROUTER SMARTPHONE [351] DATA ONLINE BANKING CENTRE This user has an app on their DATA CENTRE smartphone that lets them connect to a data centre in order to check Buildings called data centres are home to their bank account (follow the thousands of powerful computers with direct purple arrows). access to the Internet backbone. They are usually owned by a single organization, such as a bank, THERMOSTAT IN a university or a search engine (see pp.352-3). HOME MONITORS AND CONTROLS TEMPERATURE

THE DIGITAL DOMAIN WORLD WIDE WEB The most common way to use the Internet is to run Other pages, such as search results and online bank a program called a browser that can access pages of statements, are produced on request, selecting and information stored on computers called servers. Each updating information that is relevant only to the user page contains links to other pages, forming a web of requesting them. On interactive pages, such as social interconnected information – the World Wide Web. media pages, users can modify the content. Every page Billions of people follow these links to surf the Web has a unique address that identifies it – as does any other for information, entertainment and business. Some piece of information available on the Web, such as a pages are written and uploaded to a server, where they digital image, sound or video file. Each of these items is remain, ready to be downloaded by a browser onto a a resource, and its address (such as www.example.com) user’s computer or other Internet-connected device. is called a uniform resource locator, or URL. WI-FI CONNECTS SEARCHING THE WEB LAPTOP TO ROUTER The best way to find information on the Web is to use a search engine. Words typed into a 1. SEARCH TERMS 2. SENDING THE REQUEST form on the search engine’s web page are sent to a data centre (see p.351), where the search This user types the search The request is sent first to the engine company holds a vast index of web term “mammoth fur science” router (see p.349) and then pages. The search engine finds pages containing into a form on the search across the Internet to a data the words being searched for, and sends the engine web page. centre owned by the search URLs of those pages back to the browser. engine company. DATA CENTRE MAMMOTH 3. SEARCHING LIST OF THE INDEX RESULTS At the data centre, a computer scans an index of web pages, looking for “mammoth”, “fur” and “science”. The more often the words appear in a page, and the closer together they are, the more relevant the page is likely to be. CLICKING ON A LINK 4. REQUESTING A WEB PAGE The search engine computer at the data centre prepares When the user clicks on a page’s URL, the computer a web page that contains the results of the search – a list sends a request, via the router, across the Internet to of the web pages it has found that are relevant to the the server where that web page is stored. Most servers information the user is looking for. It sends the results are owned by an Internet Service Provider (ISP). page via the Internet back to the user’s computer. Each result that appears on the list is accompanied by a link to its URL. Clicking on one of the links instructs the brower to download that particular web page. [352]

WEB SERVER, SENDING BITS OWNED BY WISE OWLS INC. SCIENTIST SCANS RARE SAMPLE OF MAMMOTH FUR FOR WEB PAGE 5. SENDING THE WEB PAGE One of the search engine results that looked promising to the user was a page written by a scientist who studies mammoth fur. The web server sends the page and the images it contains back to the user’s computer, via the Internet. WRITING WEB PAGES Web pages are written in a computer language called hypertext markup language (HTML), which enables web designers to mark up, or style, how the text will look when it is displayed on a screen. HTML uses “tags” to mark up the text – for example, <p> to make new paragraphs, <img> to insert pictures, and <a> to insert links to other pages and resources such as images and videos. These links are called hyperlinks and each hides a URL. When a web page is displayed in a browser window, clicking or tapping on a hyperlink causes the browser to download the linked resource. Text containing these hyperlinks is called hypertext. HYPERLINKS DISPLAYED IN COLOUR AND UNDERLINED EACH IMAGE HAS OWN URL 6. VIEWING THE WEB PAGE When the web page and its images have been received, the browser displays them as a page. The page also contains links to other URLs for other pages, images, sounds and videos on the fascinating topic of mammoth fur. [353]

THE DIGITAL DOMAIN SATELLITE NAVIGATION You can find out where you are, anywhere in the world, using satellite navigation. A receiving device, often installed in a ship or a car, picks up digital radio signals from navigation satellites orbiting Earth. Each satellite broadcasts a precise time and location signal. By comparing the signals from several satellites, the receiver can work out its own position. The position is then shown on a map, and can be tracked in real time, as the device moves. Smartphones can fulfill the same function, using antennas and microchips that detect the satellite signals, combined with maps stored in their memory or downloaded over the Internet. SHOWING THE WAY Smartphone apps can use satellite signals to display the user’s location on a map. Software allows the user to key in their desired destination and receive turn-by- turn directions in order to reach it. [354]

SENDING BITS GPS HOW IT WORKS There are several satellite navigation Each satellite broadcasts a signal containing systems in operation. the satellite’s exact position and the time The best known is the the signal left the satellite. The receiver Global Positioning picks up the signal and works out how System (GPS), a long the signal took to travel from the “constellation” of more satellite. This allows the receiver to than thirty satellites calculate its distance from that satellite. in low-Earth orbit By working out its distance from three (see p.249). different satellites, the receiver can work out its own location to within a metre or so. With data from a fourth satellite, it can also work out its altitude (height). [355]

THE DIGITAL DOMAIN CHAPTER FIVE Pressed into the floor in the centre of the space were four footprints, which to Mammoth’s amazement precisely W“ ell, here we go,” said Bill, coaxing the reluctant matched his own. No sooner had he placed his feet in them mammoth away from a pile of discarded chocolate­ than two small orchestras complete with sheet music were coated apples and into a large building where workers were rolled into position next to his ears. Mammoth was already fastening the last of the smeared strips together. They had beginning to feel a little claustrophobic, and when a large created a single, large piece of paper, which they then piece of machinery gently wrapped itself around his head, stretched between two rollers. he let out an extraordinary wail. [356]

USING BITS At that very moment, the musicians began to play – Most importantly, however, he thought he saw other or more accurately to recreate – almost identical mammoths – lots of them. He couldn’t believe his tear-filled trumpeting sounds. Then the paper began to roll past his eyes. The years of loneliness were over. Solitary wandering eyes, which made the individual smears blur together, would be a thing of the past. As the sounds grew louder and creating not only an amazing landscape but one which more wonderfully cacophonous, his head swung back and seemed to be in motion. When Mammoth turned his head forth to take it all in. Feeling a pleasant dizziness, he stood to follow a particular sound, the scene shifted in exactly still for a moment and noticed that one particularly that direction. Endless clumps of swamp grass swayed beautiful mammoth was approaching him. gently in the breeze. [357]

THE DIGITAL DOMAIN [358]

USING BITS USING BITS He was helplessly in love. She was wearing a bow in On its journey through the digital domain, the her hair and a name tag. He was at some kind of mammoth first saw personal details such as its mammoth software convention. And then he remembered dimensions, image and sound changed into numbers. that mammoths didn’t attend conventions! They flouted These were stored, then processed to produce new them. But she came closer and raised her trunk to kiss him. numbers, while yet more numbers arrived from This was too good to be true. He decided to stop thinking. elsewhere. The purpose of this number crunching now He closed his eyes and raised his trunk to return the caress. becomes clear as the bits representing the numbers are He tasted...chocolate. Chocolate? His eyes suddenly flew turned back into images and sounds so the mammoth open. All he saw were smears. can experience a virtual mammoth world. Aided by imperfect eyesight, and a little credulity, he sees and Not the little smears, but big smears. The kind of smears hears mammoths cavorting all around him. you get when you drag a drooling trunk across a piece of chocolate-covered paper. He was stunned. Then he was The new friends are, in fact, near furious. He shook the contraption from his head. The replicas of himself. The original orchestras took cover where they could. By the time bits giving the Mammoth calmed down, he was devastated. He felt mammoth’s details have cheated. Humiliated. It had all been some kind of trick. been processed to “Not a trick,” said Bill somewhat defensively. “Progress.” produce bits that form images of a variety of mammoths in motion. The sound bits have undergone processing to provide a vocabulary of calls. From the mammoth museum have come bits representing a typical mammoth landscape, and bits that give information on mammoth lifestyles so that the virtual mammoths will move and call realistically. But for us, the digital domain becomes an actual reality as the bits that have been made by an input unit of a digital machine, communicated to the machine, stored in its memory and processed by its processor, are changed back into forms that we can understand and use. The bits become words, numbers, images, sounds or movements in output units such as printers, screens, loudspeakers, simulators and robots. NUMBERS AT WORK Thus do numbers serve us. Digital machines have changed the world and the ways in which we live because almost everything can be represented by a string of numbers. Once something is in numerical form, the numbers can be easily and swiftly changed to represent actions that are difficult or impossible to achieve by mechanical means. Digital machines not only outstrip and outperform their mechanical forebears. They inspire new kinds of things, new things to do and new ways in which things are to work. [359]

THE DIGITAL DOMAIN DIRECT OUTPUT Sequences of bits in the form of on-off electric pulses INCOMING BITS arrive at the output unit of a digital machine or (SEE P.352) system. If they are then arranged in a grid or array, bits representing an image or a character, such as a letter, PRINT JOBS form a pattern that reproduces the image or character. The bits go directly to a printer mechanism to be printed The computer processes the in this pattern. Bits representing characters also go document to be printed and sends directly to alphanumeric displays. it, with information about paper INK-JET PRINTER size and number of copies, as a binary file called a print Also known as a bubble-jet printer, this printer contains a job. The print job can be print head that moves back and forth across the sheet of sent along a USB cable paper, which moves up after each pass. The print head fires (see p.369) or over a tiny jets of ink onto the paper to produce rows of dots that network (see p.349). build up into images and characters. Each on-pulse (binary 1) fires the print head to ink a dot; an off- INK-JET NOZZLES pulse (binary 0) does not fire the head. An enlarged view of the nozzles. Each PRINT HEAD INK-JET one fires about 10,000 times a second. NOZZLES The head contains an ink chamber, and vertical rows of very fine nozzles that fire jets of quick­ drying ink at the paper. INSIDE AN INK-JET An ink-jet printer works by forming bubbles in the ink, hence its other name of bubble-jet printer. CABLE BRINGING BITS TO PRINT HEAD 1 INK TUBE 2 BUBBLE FORMS Inside each nozzle of the print A pulse of electricity heats up the head is a tube containing a element, instantly vapourizing heating element. Ink is fed to it. some of the ink to form a bubble. COLOUR PRINTER 3 BUBBLE EXPANDS 4 TUBE FIRES Colour ink-jet printers contain four separate print heads that fire jets of yellow, magenta, cyan and The bubble grows rapidly as the A jet of ink leaves the tube and the black inks at the paper. The coloured dots merge heating continues, and begins to heating stops. The bubble collapses, to form a full-colour picture (see pp.185 and 216). force some ink out of the tube. sucking in more ink. Three eight-bit colour numbers in the digital colour signal (see p.327) give the shade of each colour to be printed, and the print head fires a varying number of separate small dots. A light shade results from a few small dots spaced out, and a heavy shade from lots of close-spaced dots. A colour laser printer works in the same basic way, except that the paper makes four passes and the drum is fed with toner powder in the four different colours. [360]

USING BITS ALPHANUMERIC DISPLAY A simple display showing numbers, made up of the ten decimal numerals from 0 to 9, appears on many digital machines. These include the pocket calculator, digital watch, digital thermometer and digital scales. Some machines, such as radio sets, also display letters of the alphabet. Each character (numeral or letter) is formed of several segments; numerals contain seven segments. On-off bits go directly to the segments in the display, and the on bits cause some of the segments to go dark. The resulting pattern of dark segments forms a number or letter. LIGHT DISPLAY SEGMENT DARK SEGMENT EYE TO EYE A printed picture or document consists of a grid of rows of tiny dots printed one after another. From normal viewing distance, the dots merge together to form images and characters. This is a print of the eye scanned on page 325. LASER PRINTER DECODED 7-BIT NUMBERS DECODER The printing action of a laser printer is exactly the same as a photocopier (see p.260). The incoming INCOMING 4-BIT on-off bits cause a laser or LED (see p.273) to fire NUMBERS rows of on-off flashes of light at the printing drum and build up dots in the image. INCOMING BITS LIGHT FLASHES LASER OR LED LENS SEVEN-SEGMENT DISPLAY The segments in an alphanumeric display work with liquid SPINNING crystals (see pp.194-5). Natural light is either reflected from MIRROR the display, or a light source is placed behind it. When an FLASHES OF electric current goes to the segment, the liquid crystals inside LIGHT SPREAD it block the light so that the segment goes dark. Bits IN ROWS representing the characters to be displayed go to the display ACROSS decoder. For numerals that have seven segments, these bits ROTATING may be the four-bit binary equivalents of the decimal DRUM numerals to be displayed, so that 0011 arrives to become a 3, and 1001 arrives to become a 9. The decoder changes the PRINTING DRUM four-bit numbers to seven-bit numbers, and each of the seven bits controls one of the segments. An on-bit (binary 1) causes a current to go to the segment and darken it; an off- bit (binary 0) stops the current and lightens the segment. [361]

THE DIGITAL DOMAIN SIGNAL OUTPUT DIGITAL-ANALOG CONVERTER (DAC) THREE-BIT CONVERTER 5 VOLTS The converter shown here Output units that produce sound through loudspeakers turns the three-bit digital FIRST SECOND THIRD and earphones, as well as images on screens, do not signal 101 (on-off-on) into BIT BIT BIT work directly with bits. They require an analog electric an analog signal of five volts. 1 0 1 signal with a varying voltage. The incoming digital Only three bits are shown for sound and image signal, which consists of bits in the simplicity. In practice, DACs form of on-off electric pulses, first passes through a convert digital signals of 8, digital-analog converter. This is the reverse of the 16, or more bits. analog-digital converter that changes sound and light to bits when they enter the digital domain (see p.322). CURRENT OF 5 VOLTS EMERGES 4 VOLTS 0 VOLTS 1 VOLT FROM DAC RESISTOR REDUCES VOLTAGE TO A HALF RESISTOR REDUCES INSIDE A DAC VOLTAGE TO A QUARTER IF TRANSISTOR 2 IS ON The incoming bits go to separate wires connected to transistor switches. These control an electric current going to resistors that reduce the voltage of the current to a half, a quarter, an eighth, and so on. TRANSISTOR 1 ON TRANSISTOR 2 OFF TRANSISTOR 3 ON 8-VOLT SECOND BIT THIRD BIT RESISTOR CURRENT REDUCES GOES TO ALL VOLTAGE TRANSISTORS TO AN FIRST BIT EIGHTH DOUBLE, DOUBLE Each resistor has double the value of the next resistor, which ensures that the value of the final voltage is equal to the binary number fed to the DAC: 101 in binary is 5 in decimal. DIGITAL SOUND which converts them to an analog signal. The signal passes to an amplifier, which makes the signal powerful Inside a digital device, such as a smartphone or tablet, enough to drive the speaker (see p.232). The speaker sound is represented digitally, as a sequence of bits – produces a sound wave that is a copy of the analog signal. thousands or millions of bits for every second of sound. To reproduce the sound, the bits pass through a DAC, INCOMING LOUDSPEAKER DIGITAL SIGNAL CONE DIGITAL-ANALOG CONVERTER ANALOG SOUND AMPLIFIED SIGNAL SIGNAL AMPLIFIER MAKING SOUND WAVES The cone of a loudspeaker vibrates in step with the variations in the signal, producing a sound wave that is a copy of the analog signal. [362]

USING BITS SPEECH RECOGNITION When you talk into a smartphone, its processor can work out the words you say by identifying the sounds that make up spoken language, which are known as phonemes. The sound of your voice is a SMARTPHONE mixture of many different frequencies (see p.242), from low-pitched to high-pitched. Each phoneme has a different mixture of frequencies, so the SOUND WAVES TRAVEL ELECTRICAL processor identifies each phoneme by THROUGH THE AIR SIGNAL analysing the sound wave your voice produces. 1 BREAKING IT DOWN The phone’s microphone captures the sound of your voice as an SPECTROGRAM electrical signal, which is a precise copy of the sound wave. The processor breaks down the signal into its various frequencies, producing a pattern called a spectrogram, which has low frequencies at the bottom and high frequencies at the top. Different phonemes produce different patterns on the spectrogram. As each phoneme is spoken, the mixture of frequencies changes, and so does the spectogram. LONGER SHORTER WAVES PHONEMES WAVES ARE ARE HIGH LOW FREQUENCY FREQUENCY The smartphone compares the spectrogram of the incoming sound with examples of each of the pre-recorded phonemes stored in the phone’s memory. The range of phonemes depends on which language is being used – for CHANGING PATTERNS example, English has 44. Phonemes are produced by closing or opening your lips or the back of your throat, or by pushing your tongue against your teeth or the roof of your mouth. Each action dramatically changes the mixture of sounds that make up your speech. 2tTtiTnyhhhpsReeeiedoEdpwetChriotoneOhrcrdeo,eNssntposSchoaaTrornekRnccenUeooyo,nnbCwjnsouTteasrbIcrtueNdtacsrstFbTiG(detesthtIhepiehNhennTereeegtDseHipymfpswsIihepeNE.aw3soonorGk1trWowtnpdee7uhAhends)ilomOcd.aMtnahhteeRsbAa’psaseDsnThtpteyoCorihSqfnogmHaucetevemhoetsemnehseoybceeirsneerhtse.oanodnfsebpbaeoifettksneernBSEI.LTEWNECEENINWORDtocSoamtrsahedeueHve-twmomhIptonoiaoee”wcautnr,naeheipsdawlddrtee,hppclshnisyvslhooochrpweheseoiotrmtnpotecaarhRpgobnreanyhtvt3mereorreeioeeawoqwodadccprP’ammsccunfsoeaiuhihnifhelHscpengsfolloefdsseetcsornodrtsshnRu,tsraohe–ureioieaealszaAcooqenlrncauvmlnineenrlfunSedtercysdotgeretegaEseh–mtthttsbsrnonaxoahSslapeiaerechsteipnlemnosecwaeaAasahmenonnsnpsw“vmeoaewNatnPidegeecsrsfnhmhasnb.eushDphbwigisrceieadcoeoaecshiccogthSenksg.ehboaternneeieOEauudstnmsNtsisnd.fe,phicoiTefoesadfdoEkivetcmeehNluneleC,t ES [363]

THE DIGITAL DOMAIN VIRTUAL REALITY The one way in which you can enter a digital domain is to put on a virtual reality headset. You find yourself in a world created by the computer. Objects are moving all around you and you can hear their sounds. As you move your head, the scene and sounds move too, just as if you were actually there and looking around, up, or down. In fact, you are looking at two small screens and listening to earphones. The computer connected to  the headset is able to react to your movements because the headset contains a sensor TRACKING SENSOR that detects your head A motion detector similar to that in an air bag (see p.292) produces an electric signal as you turn, raise, or lower your head. Virtual reality movements. machines may also use detectors that track other movements, such as your hands. EARPHONES A pair of earphones (see p.233) produces stereophonic sounds that come from all angles. –Tnhai su si se avti irnt gu .a l l y SCREENS COMPUTER CABLE Two liquid crystal screens (see pp.246-7) The computer processes display a pair of images, which are slightly incoming bits from the tracking different so that your brain combines them to sensor and returns output bits create a three-dimensional scene. that control the image and sound output accordingly. FI FIDO 1 LOOKING AHEAD 2 LOOKING AROUND 3 LOOKING LEFT You see a three-dimensional view of a You hear a dog barking in your left ear. The dog appears, and the barking kennel as the pair of screens display As you turn your head towards it, the sound is now in front as sounds come two images of the kennel. images shift to the right. from both earphones. [364]

USING BITS FLIGHT SIMULATOR Virtual reality is a valuable way of training aircraft PROJECTORS CURVED MIRROR pilots. A flight simulator contains a mock-up of the aircraft flight deck. The pilot sits at the controls and High-quality projectors The pilot looks through the through the windows sees a real airport and moving throw adjacent sections of windows of the flight deck pictures of scenes that occur during take-off, flight, and a wide, colour, computer- at a wide, curved mirror landing. The pictures are generated by a powerful generated picture onto a that extends around the computer connected to the controls. As the pilot curved screen that extends windows. The mirror reflects handles the controls, the computer processes around the flight deck. the back-projected picture the  operations and sends output bits back to the Half of the screen can be on the screen. This optical simulator. These move the picture, vary the instrument seen here with two of the system makes the image displays, sound warnings, and tilt the flight deck three projectors working. appear to be a long way exactly as if the aircraft were flying. The computer can off. Half of the mirror is switch to night landings or foggy weather, or shown here. conditions  that require an emergency landing such as an engine failure. It can also record a “flight” and CURVED SCREEN replay it so that the pilot and instructor can go back over the training exercise. INSTRUCTOR STATION Behind the pilot, the instructor sits at the computer console, controlling the simulator’s computer and assessing the performance of the pilot. JACKS Jacks beneath the simulator move in and out to tilt the simulator and mimic aircraft motion. [365]

THE DIGITAL DOM ACTUATORS The components that make parts of the robot move are called actuators. They include stepper motors (see p.283), which can make precise movements, as well as hydraulic rams (p.129). The movements are controlled and synchronized by the robot’s main computer. ELBOW BENDS SHOULDER WHOLE ARM SWIVELS ROTATES ANGLE SENSOR WRIST MOVES In the joints of a robot arm that rotate, UP AND DOWN a sensor detects the angle through which ROBOT CLEANER the joint is turning. This often consists CHARGING STATION of a light beam shining through a slotted wheel to a detector, to give an electric INDUSTRIAL ROBOT pulse every time a slot passes. Counting the pulses calculates the angle turned. Robots are frequently used to assemble parts on a production line. Industral robots DETECTOR can perform complex actions using an arm LIGHT BEAM whose various sections can turn around SLOTTED WHEEL six joints. These enable the robot’s hand to move in all possible directions to any position within its reach. VACUUM CLEANING ROBOT The most common robot to have found its way into homes is the vacuum cleaning robot. This finds its way around with sensors that detect edges and objects such as chairs. When the battery is low, or when the job is finished, the robot finds its way to a charging station to recharge its batteries. [366]

USING BITS ROBOT The robot is the ultimate machine, able to carry out and operate tools such as welding torches and paint a wide range of physical tasks. A sophisticated sprayers. Robots are used in many other applications, computer directs the movements of the robot’s arms, including carrying out scientific surveys in dangerous legs or other appendages, sending output bits to environments, picking and packing products in electric or hydraulic motors that move the joints by warehouses and helping care for elderly patients in precise amounts. The computer can be programmed hospitals or at home. Walking on two legs (bipedalism) with a particular set of movements that the robot can is a real challenge for a robot. It is achieved with repeat exactly over and over again without ever accelerometers (see p.241) and pressure sensors getting tired. Therefore it is an ideal machine for constantly feeding back to a robot’s computer, which factory work, especially on assembly lines producing rapidly adjusts joints in its legs to keep its balance. complicated machines Some robots can recognize certain objects and faces, such as cars. Some thanks to onboard video cameras and sophisticated FOREARM robots can handle image-recognition software. As computing power ROTATES parts, fitting them in increases, artificial intelligence is allowing some robots place precisely, while to become more and more autonomous. other robots can hold HAND TWISTS SENSORS ROBOT VISION Sensors relay information back to the robot’s Video cameras provide a robot with vision, which main computer. Pressure sensors enable the gives useful feedback to help it accomplish tasks. computer to work out if it has picked up an An onboard computer runs image-recognition object, and to adjust its grasp to make sure software, which can help identify things to avoid that it doesn’t break an object it is holding. or to aim for. For example, a football-playing robot can identify the ball, the goal and other BIPEDAL players. With two video cameras, set slightly HUMANOID ROBOT apart like human eyes, a robot acquires a sense of depth to help it accurately work out distances – important when kicking a ball to score a goal or to pass to a teammate. BIPEDAL ROBOT Bipedal robots can be programmed to play football, interacting autonomously with other robot team members, tackling, kicking the ball – but rarely breaking the rules of the game. [367]

THE DIGITAL DOMAIN COMPUTER Acomputer – desktop, laptop, tablet or smartphone – is the ultimate digital device. It can communicate quickly with other digital devices and link to the Internet, using Wi-Fi, Bluetooth and network cables. A computer’s mainboard contains a powerful processor chip as well as large amounts of RAM to run the software applications. Software and data are stored on a hard disk or solid state drive, while additional storage can be connected in the form of flash drives and external hard disks. Computers have many different forms of input and output. Most of these “peripherals” connect via USB cables. WI-FI ANTENNA IN SCREEN BLUETOOTH KEYBOARD SPEAKER (SEE P.317) BLUETOOTH TRACKPAD BLUETOOTH CHIP Bluetooth® is a radio signal that allows a computer and other digital devices to connect wirelessly over short distances, usually in the same room. ROUTER MAINBOARD PROCESSOR CHIP (SEE P.349) (SEE P.344) (SEE P.344) RAM CHIPS (SEE P.333) COOLING FAN BATTERY MICROPHONE AND USB PORTS HEADPHONE JACKS AND NETWORK A laptop can be portable, thanks CONNECTIONS to a lightweight, rechargeable [368] SD CARD battery, which can typically (SEE P.334) provide power for up to 7 hours. WIRELESS MOUSE (SEE PP.318-9)

USING BITS MINI USB B GETTING CONNECTED USB A The most common way to connect USB B peripherals such as external storage devices, printers and digital cameras USB C is to use a USB cable. A computer acts as a USB hub, which means it can connect several USB devices at the same time. USB stands for “universal serial bus”. A serial connection is one in which the binary digits are transferred one-by-one, but nevertheless USB cables can carry billions of binary digits (gigabits, or Gb) every second. There are several standard fittings, which allow different devices to connect together. They are known as “A”, “B” or “C” fittings. PRINTER Modern printers can also function as scanners (see pp.326-7). They typically connect to a computer via USB, or wirelessly across a local network (see p.349). USB C MULTI-FUNCTION PRINTER USB FLASH DRIVE DIGITAL CAMERA (SEE P.334) (SEE PP.204-5) USB A EXTERNAL HARD DRIVE (SEE P.333) CONNECTING PERIPHERALS Input and output peripherals can be connected via ports on the edge of the mainboard. This is one way, for example, of transferring photographs from a digital camera to a computer. USB A TO MIDI KEYBOARD USB B CABLE (SEE P.316) [369]

THE DIGITAL DOMAIN SUPERMARKET Every time you make a purchase at a supermarket IN-STORE COMPUTER checkout, you come into contact with a huge digital Digital signals pass to and system. The supermarket company uses a vast from the central computer network built around the central computer computer via the at the head office. This communicates to a ring of instore computer. depots in different locations. Each depot computer Every night, this updates each links in turn to a ring of individual stores. Each store checkout computer contains an in-store computer that is connected to the with price changes computer in each checkout. The central computer is and new products. also linked to a network of bank computers. LINKS TO IN-STORE CHECKOUT COMPUTER COMPUTER Hard disk (see p.335) stores the name and price of thousands of products. SWIPE-CARD ALPHANUMERIC DISPLAY BARCODE FIDO READER (SEE P.336) (SEE P.361) SHOWS PRICES, READER SENDS YOUR CARD NAMES AND TOTAL BILL (SEE P.337) NUMBER TO THE CENTRAL KEYPAD BAR CODE COMPUTER (SEE P.316) STORES PRODUCT NUMBER CREDIT CARD ELECTRONIC SCALES OR DEBIT CARD (SEE P.323) SEND CUSTOMER BUTTONS WEIGHT OF PRODUCT TO AUTHORIZE PAYMENT CHECKOUT COMPUTER

INDIVIDUAL BANK BANK STORES DEPOT BANK BANK NETWORK Your payment goes to your bank, which sends the amount from your account to the supermarket account. BANK MAMMOTH MART INDIVIDUAL PRINTED RECEIPT SUPERMARKET’S STORE BANK LINKS Printer (see p.360) prints HEAD OFFICE TO HEAD OFFICE out full receipt with the BANK NETWORK names and prices of all LINKS TO MORE DEPOTS The central computer checks your products purchased. card number, and sends a signal back DEPOT to the checkout allowing purchase. It also collects details of all The depot computer purchases for stock control and receives instructions orders suppliers to send more from the central stock to depots. computer to send more stock KEYBOARD (SEE to stores. P.317) MAY INPUT PRODUCT DETAILS INDIVIDUAL STORE INDIVIDUAL STORE INDIVIDUAL STORE [371]

THE DIGITAL DOMAIN [372]

EPILOGUE EPILOGUE While Mammoth had been impressed by much of the digital domain, there was also plenty about it that left him feeling uncomfortable. In the end, it was just too much, too big, too fast and too unfamiliar. Mammoths, after all, had never really embraced the concept of progress and this one wasn’t going to start now. In fact, as he left the digital domain, he had no intention of ever returning. Bill, smiling down from the top of the wall, knew differently. While it was true that the mammoth hadn’t developed much of an appreciation for digital technology and all that it could complicate, he had developed a real taste for pumpkin pie and apples smeared in chocolate. These were a pleasant and entirely compatible replacement for swamp grass, which would soon be extinct. And Bill was the only supplier for miles and miles. [373]

THE MECHANICS OF MOVEMENT EUREKA! THE INVENTION OF MACHINES THE INCLINED PLANE THE ZIPPER danger to the user. The safe and simple can openers that we have today were not People have to eat to live and, necessity The zipper took quite a time to make invented until the 1930s, more than a being ever the mother of invention, the its mark. It was invented by American century after the appearance of the tin can. very first machines to be invented were the engineer Whitcomb Judson in 1891, not in its present form as a clothes fastener, but as LEVERS tools used by prehistoric people in a device to do up boots. It did not take off hunting and gathering their food. until 1918, when the US Navy realized that Levers also originated in ancient times in Stones crudely chipped to form Judson’s invention would make an ideal devices such as hoes, oars and slings. tools date back more than fastener for flying suits. The name zipper, People realized intuitively that levers could 3 million years, and stone coined in 1926, clinched its success. aid their muscle power, but it took a genius axes and spearheads litter to explain how levers work. The genius was archaeological sites down THE CAN OPENER the Ancient Greek scientist Archimedes to the dawn of civilization. (287-212 bce), who first defined the In cutting tools, the Methods of preserving food in sealed principle of levers. He illustrated it with inclined plane became containers were invented in the early 1800s, the famous adage “Give me a place to the first principle of at first using glass jars and then tin cans. stand and I will move the Earth” – meaning technology to be put to The cans were ideal for transporting food, that if he had a lever sufficiently long, he work. On a larger scale, but opening them could be a problem. At could shift the Earth by his own efforts. it may have enabled first, a hammer and chisel – a crude use of people to build at least the inclined plane – had to serve. Claw-like The formulation of the principle of one of the Seven devices and levered blades were then levers was a landmark in the development Wonders of the World devised to open cans, not without some of science and technology. Archimedes’ – the Great Pyramid. insight explained not only levers, because This was built in the same principle lies behind the inclined Egypt in 2600 bce plane, gears and belts, pulleys and screws. using high earth Furthermore, Archimedes showed that by ramps to raise great making observations and experiments, stone blocks into it was possible to deduce the basic position. principles that explain why things work. THE PLOUGH The plough was invented in the Middle East in about 3500 bce. At first, it was little more than a digging stick drawn by a person or an ox, but this primitive plough enabled people to dig deeper than before. Plants could put down stronger roots in ploughed soil, increasing crop yields and enabling farmers to produce a surplus of food. The plough thus freed some people from the necessity of growing their food. LOCKS WEIGHING MACHINES Locks existed in Ancient Egypt, and they The first device to make precise use of made use of pins in the same way as the levers was invented long before Archimedes’ cylinder lock. The application of the time. This was the balance or scales used inclined plane to the key, made by Linus for weighing, which dates back from Yale in the United States in 1848, is one of 3500 bce. It may seem odd that a precision those fundamental inventions that long instrument was required so long ago: outlive their maker, and the cylinder lock however, what had to be weighed was no is still often called a Yale lock. The lever ordinary material – it was gold. Gold dust lock dates from 1778 and was invented by was used as currency in the ancient British engineer Robert Barron. The design civilizations of the Middle East, and resulted from a need to prevent burglars amounts of it had to be weighed very taking wax impressions inside locks and precisely in order to assess their value. then making keys from them, and it too proved to be a fundamental advance. [374]

REKA! KEYBOARD MACHINES same way as the hour hand of a mechanical clock. The piano was invented in Italy in 1709 by Bartolomeo Christofori, who sought a The oldest surviving mechanical clocks way of varying the volume of a keyboard date from the late 1300s. Gears transmitted by using levers to strike the strings with the constant movement of a regulator to the hands or to a bell. A good regulator different amounts of force. His success appeared only with the discovery of the is reflected in the instruments name: pendulum in 1581 by the great Italian the pianoforte or “soft-loud”. The scientist Galileo, who timed a swinging lever system was later improved chandelier with his pulse and realized that to increase the response of the the time taken for each swing was always piano, resulting in the highly constant. Even so, it took nearly a century expressive instrument that for the first pendulum clocks to appear. affected the whole course of music. THE WHEEL AND AXLE seeking to maximize energy output. THE EPICYCLIC GEAR The Francis turbine, invented by James The development of mechanical power Francis in 1850 and now common in The sun-and-planet or epicyclic gear is of has its origins in the wheel and axle. The power stations, was literally a product of much more recent origin than other types. first machines to make use of this device lateral thinking because Francis made the It was invented in 1781 by the great may well have been the windlass and the water flow inwards instead of outwards. British engineer James Watt, who is best winch. The Greek physician Hippocrates, known for improving the steam engine. who was born in 460 bce, employed a GEARS AND BELTS Watt needed a device to turn the windlass to stretch the limbs of his reciprocating motion of the piston of his patients, a treatment uncomfortably like Belts are simple devices, seen in the chains steam engine into rotary motion, but he the rack of medieval torture chambers. of buckets that lifted water in ancient could not use the crank because someone Winches have been used to draw water times. The basic forms of gears were else had patent protection on it. Watt’s from wells for many centuries. known by the first century ce. An alternative was the epicyclic gear, now extraordinary early application of gears is found in salad spinners, automatic THE WATERWHEEL AND WINDMILL the Antikythera mechanism, a mechanical transmission and many other devices. calendar made in Greece in about 100 bce The waterwheel dates back to Greece and recovered from a wreck sunk off the THE DIFFERENTIAL in about 100 bce, and it was developed Greek island of Antikythera. This machine by the Romans to power water mills had 25 bronze gear wheels forming a This first appeared in the “south-pointing grinding corn. The wheel had horizontal complex train of gears that could move carriage” invented in China in the third blades angled so that a stream of falling pointers to indicate the future positions of century ce. The two-wheeled carriage was water could turn the wheel. Its advantage the Sun and Moon as well as the times surmounted by a figure that always was that the vertical shaft of the wheel when certain stars would rise or set. pointed south, no matter how the carriage drove the horizontal grindstone directly. turned as it moved. The figure was set to The bad news was that it required fast- CLOCKS south, and then a differential driven by the flowing water and produced little power. wheels turned the figure in the opposite The vertical waterwheel, first described A rack-and-pinion gear was used in a direction to the carriage so that it still by a Roman writer in about 15 bce, is far water clock built by the Greek inventor pointed south. more practical and it soon replaced the Ctesibius in about 250 bce. The water Greek wheel. clock was an ancient device in which Such a machine must have appeared water dropped at a constant rate into a magical to the people of the time. However, Rather like the first waterwheel, container, the level of the water indicating calculations show that the mechanism the first windmill was powered the time. Ctesibius improved it by having could not have been sufficiently precise for by a horizontal wheel a float raise a rack that turned a pinion the figure to point south for long. Within bearing vertical sails. connected to a pointer on a drum. The 5 km (3 miles) it could well have been It was invented in pointer turned to indicate the time in the pointing north instead! Iran in about 640 ce. The vertical windmill, also more practical, was invented in Europe in about 1170. TURBINES Modern turbines are a product of the Industrial Revolution, when the demand for power soared as factories developed. Engineers investigated blade design, [375]

ENT THE LIFT AND ESCALATOR Metal screws were used as a superior alternative to nails in 1556, when the The lift is a relatively recent invention, the German mining engineer Agricola reason being that buildings had to reach described how to screw leather to wood to quite a height before they became make durable bellows. The screwdriver necessary. Although lifts are intended for however did not follow until 1780. public use, the very first lift had exactly the CAMS AND CRANKS opposite purpose. It was built in 1743 at the Palace of Versailles for the French king Cams and cranks are old devices too – Louis XV. Counterbalanced by weights and the cam appearing in the drop hammer operated by hand, the lift carried the king in and the crank in a winding handle. Their total privacy from one floor to another. application in the sewing machine was developed during the early 1800s, the The modern safety lift is the invention of first successful sewing machine being the American engineer Elisha Otis, who produced in the United States by Isaac dramatically demonstrated its effectiveness Singer in 1851. The four-stroke internal in 1854. He ordered the rope of the lift combustion engine, which similarly carrying himself to be cut. The emergency depends on the controlling movement braking system was automatically of cams and cranks, was first put to use activated, and the lift did not fall. in the motor car by Karl Benz in 1885. These two machines are still with us Escalators date from the 1890s. The first in their basic form today, along with models were basically moving belts and their inventors’ names. had no steps, so could only carry people up or down a gentle incline. SCREWS THE COMBINE HARVESTER The screw is yet another machine The combine harvester is the most associated with Archimedes, for the earliest important invention in farming since the known is the water-lifting auger know as plough, and a modern harvester makes use Archimedes’ screw. However, it may well of several augers that work in exactly the have been invented before his time. The same way as Archimedes’ screw. The first combine harvester was built in 1835 by screw press, which combining a horse-drawn reaper and a contains the form threshing machine. It took a century to of screw used in develop the harvester into an effective nuts and bolts, self-powered machine. was first described by Hero of Alexandria. PSwywaspawiebaUmhsuiaitoehedlrhLpiuleosgeltLltsrehyaoseetEgtc.vwhtheohrYeTedaea,arhvSrn4aatleeielne0wftsiwdi0sninahnsuhvscvagsbeoeeadicnenmnmboeltgtlso.epaeedfdAcsdo,tihauornsaatciongnehhccmldeoaoebim,uuemappiclnsue3upkadtla,loel0lelestreus0oshy-yon0siipsdof [376] ancient origin.

EURFKA! THE MICROMETER This important device based on the screw was invented in 1772 by James Watt. Watt’s micrometer worked in much the same way as the modern micrometer, and was accurate to a fiftieth of a millimetre (one-thousandth of an inch). ROTATING WHEELS SPRINGS DRILLING MACHINES Ancient peoples could easily move heavy Springs are also of ancient origin, being Drilling, which is basically pounding or loads by rolling them on logs, and one used in early locks. Metal springs date from grinding, is a surprisingly old activity. The would expect that the wheel developed in the 1500s, when leaf springs were invented Chinese drilled oil wells some hundreds of this way. But this is not the case. Unlike a to provide a primitive suspension for road metres or yards deep as early as the third roller, a wheel requires an axle on which to carriages. Springs did not become common century bce. They dropped a metal drilling turn and so the potter’s wheel was the first until two centuries later, when coil springs tool into the hole to break up the rock. true wheel. It was invented in the Middle were invented. The first modern oil well, drilled by Edwin East in about 3500 bce. From the potter’s Drake in Pennsylvania in 1859, was drilled wheel, the wheel was soon developed SPRING BALANCE AND HAIRSPRING in the same way. for transport. The principle behind the spring BEARINGS THE BICYCLE balance – that the extension of a spring is proportional to the force acting on it – Devices to reduce friction are of ancient The first bicycles were pushed along was discovered by the English scientist origin, the first being log rollers placed by the feet and not pedalled. They were Robert Hooke in 1678 and is known under an object that novelties rather than a serious means as Hooke’s Law. Hooke also invented was to be of transport, and were known as hobby- the spiral spring known as a hairspring, moved. horses. Kirkpatrick Macmillan, a which is used as a regulator in mechanical To blacksmith, invented the pedal-operated watches and which made portable work bicycle in Britain in 1839. Raising the timepieces possible. effectively, feet from the ground to turn the pedals a wheel required the rider to make use of FRICTION needs precession to balance. bearings People have been making use of friction on its axle. These were invented in GYROCOMPASS ever since they first set foot on the ground, France and Germany in about 1000 bce. and the first friction devices to pound The bearings were made of wood and then The inherent stability or gyroscopic inertia grain into flour date back to the greased to improve speed and lengthen of devices such as spinning tops has been beginnings of civilization. their life. Modern bearings date back to the known for centuries, but the development late 1700s. They made the development of of the gyroscope in machines is more THE PARACHUTE machines during the Industrial Revolution recent. Its most important application, the all the more effective. gyrocompass, was invented by American This was one of several inventions that were Elmer Sperry and first demonstrated on a forecast by Leonardo da Vinci, who drew US Navy ship in 1911. one in 1485. Understandably, neither Leonardo nor anyone else was very keen to try out the idea in practice. However, there was little need for parachutes until the first balloons took to the air three centuries later. The first parachute descent proper took place in 1797, when the French balloonist André Garnerin successfully dropped 680 metres (2,230 feet). Early parachutes were fashioned like huge parasols and similarly named, being proof against a chute or fall rather than the Sun.

HARNESSING THE ELEMENTS FLOATING Independence. It was an egg-shaped wooden SAILS AND PROPELLERS vessel invented by the American engineer David The first form of transport to progress Bushnell; it went into action (unsuccessfully) Sails powered boats along the under its own power was the raft. In against a British warship. The Turtle, River Nile in Egypt as long ago as prehistoric times, people must have as it was called, was very much a 4000 bce. These were square sails, hitched rides on uprooted trees that forerunner of the modern which could sail only before the happened to be floating down rivers. Rafts submersible, having wind. The triangular sail, which is borne on ocean currents probably carried ballast tanks and able to sail into the wind, first people across the world’s oceans long propellers. appeared in about 300 ce in boats before recorded history. on the Arabian Sea. The earliest known hollow boats date The propeller was invented in back to about 8000 bce. These were canoes 1836 by Francis Pettit Smith in dug out of tree trunks, which were paddled Britain and John Ericsson in the through the water. United States. It first powered The principle of flotation, which a seagoing ship, explains how things float, was one of the appropriately called the many achievements of Archimedes, the Archimedes, in 1839. great scientist who lived in Sicily (then a Greek colony) in the 200s bce. He is BALLOONS FLYING reputed to have made this discovery in his bath and then ran naked into the street The first balloon to carry passengers was a The first people to fly shouting the inventor’s classic cry of hot-air balloon invented by the Montgolfier were Chinese criminals lifted by Eureka, which means “I have found it”. brothers in France in 1783. large kites. The explorer Marco It made its first flight Polo reported the use of such kites for Although the principle that Archimedes in November of that punishment in the 1200s, but kite flying put forward explained that an iron boat year at Paris, and flew was also used to look out over enemy could float, nobody really believed this 8 km (5 miles). A few territory. Then, five centuries later, balloons and all boats and ships were made of wood began to carry people aloft. until just over two centuries ago. The days later the first development of the iron ship coincided gas-filled balloon THE AEROFOIL with the development of a powerful steam took to the Parisian engine, which drove paddle wheels in boats. skies, piloted by its The principle behind the aerofoil – that inventor Jacques increasing the velocity of a gas or liquid SUBMARINES Charles. It contained hydrogen, which also lowers its pressure – was discovered Travelling lifted the first airship into by the Swiss scientist Daniel under the water the air in 1852. This machine, Bernoulli in 1738, and the basic and into the air which was steam-powered, was invented form of the winged aircraft can be risky ventures, and by the French engineer Henri Giffard. was developed during required intrepid pioneers. the 1800s. Its design Understandably, perhaps, the inventors was due to the British of both the first submarine and balloon engineer Sir George persuaded other people to try out Cayley, who flew the their craft. first glider in 1849. This machine carried a The first proper submarine took to the child. Four years later, water in 1776 during the American War of Cayley’s coachman (against his will) became the first adult to fly a winged aircraft. On landing, he immediately gave Cayley notice! POWERED FLIGHT The invention of powered flight is indelibly associated with the Wright brothers, who flew the first powered aeroplane at Kitty Hawk in North Carolina, USA, in 1903. Unlike all modern aircraft, the wings of the Wrights’ flying machine did not have ailerons. This development came in 1908 in aircraft built by the British engineer Henry Farman. [378]

REKA! THE HELICOPTER PUMPS AND JETS hydraulics and pneumatics. One of its latest consequences is the hovercraft, Like the Wrights’ powered aeroplane, The water-lifting pump is another which was invented in 1955 by the the development of the helicopter was invention credited to Ctesibius. British engineer Christopher Cockerell. contingent upon the invention of a light However, the slow This machine began life as a pair of tin but powerful engine – the petrol engine. development of pumps cans linked up to a vacuum cleaner, The very first helicopter, built by Paul able to produce a which demonstrated that an air cushion Cornu, whirled unsteadily into the air continuous jet of could produce sufficient pressure to in France in 1907. The development water enabled the support a hovercraft. of a reliable helicopter took about Great Fire to destroy 30 years. much of London SUCTION MACHINES in 1666. The first THE HYDROFOIL proper fire engine did not appear until The vacuum cleaner also began life in 1721. The pump was invented by the Britain, where it was invented by Hubert The first use of the principle British engineer Richard Newsham. of the aerofoil was not in air It was a reciprocating pump with Booth in 1901. Again, a simple but in water. In Britain in two pistons driven alternately up and demonstration sufficed to prove 1861, Thomas Moy tested down by hand. The fire engine was reputed its viability: Booth sucked air wings by fixing them through a handkerchief to show how it beneath a boat and found to produce a jet of water nearly 50 metres could pick up dirt. However, a practical that the wings raised the (160 feet) high and to be strong enough machine was developed in the United hull above the water. Thus to smash a window. the hydrofoil was born before the aeroplane. States in 1908 by The production of a practical hydrofoil Portable fire extinguishers were took place in Italy, developed developed in the nineteenth century, by Enrico Forlanini powered at first by compressed air and in the 1910s. then by carbon dioxide. HYDRAULICS AND PNEUMATICS William Hoover, and it is his name that has always been associated with the vacuum An understanding of pressure in both cleaner. Its distant relative, the aqualung, is air and water came with the work of the also firmly associated with its inventor, the French scientist Blaise Pascal. In the French oceanographer Jacques Cousteau. mid-1600s, he discovered the principle The aqualung was developed during World that governs the action of pressure on a War II, and Cousteau subsequently used it surface. Pascal’s principle explains both to pioneer exploration of PRESSURE POWER the sea bed. The achievements of Archimedes inspired generations of inventors and engineers. First was Ctesibius, who lived at Alexandria in Egypt. Ctesibius was renowned for his self-powered devices, notably the first organ. Water was a convenient source of power and in this instrument, he used the pressure of water to drive air into the pipes: the resulting music was ear-splitting.

HARNESSING THE ELEMENTS THE FLUSH TOILET IRON AND STEEL MAKING in 1876. He was able to produce liquid oxygen with it, but such a cold liquid was difficult The water closet, the first of many Iron making dates from 1500 bce when to keep. James Dewar, a British scientist, euphemisms (though more accurate than the Hittites, in what is now Turkey, built developed the vacuum flask in 1892 to store most) for the flush toilet, dates back to furnaces to smelt iron ore with charcoal liquid oxygen, but it has since found far 1589, when it was invented by Sir John and so produce the metal itself. The wider use in storing hot drinks. Harington, a British nobleman who was a process did not develop further until 1709, godson of Queen Elizabeth I. The cistern when the British iron maker Abraham STEAM POWER in Harington’s invention worked with a Darby substituted coke for charcoal and valve that released the flow of water. added limestone. His furnace needed a The use of heat to provide motive power Harington recommended that it be flushed powerful blast of air to burn the coke, but came in a brilliant invention by the Greek once or preferably twice a day. it could make iron in large quantities – a engineer Hero in the first century ce. He factor that helped to bring about the built the first steam engine, a little device that Harington’s important contribution to Industrial Revolution. spouted jets of steam and whirled around the history of technology was centuries rather like a lawn sprinkler. Hero’s engine ahead of its time, and the water closet did The large-scale production of steel from not attain its present form until the late was of no practical use and the steam 1800s. The use of a siphon, which does iron made in engine vanished until the 1700s, when it away with valves that can leak, dates from blast furnaces did not follow was developed in Britain, notably by James that period. until the 1850s, when the steel Watt. The steam turbine was invented by converter was invented another Briton, Charles Parsons, in 1884. EXPLOITING HEAT independently by William Kelly in the United States PETROL, DIESEL AND JET ENGINES Harnessing heat was a key technological and Henry Bessemer in achievement. The discovery of fire, which Britain. Air was blown The petrol engine followed the development happened in China over half a million through the molten iron of oil drilling in the mid-1800s and also the years ago, provided heat for cooking and to form steel, a process invention of a four-stroke engine running warmth. Millennia were to pass before leading to the use of on gas at about the same time. The first heat was to be turned to much more oxygen today. two stroke engine was invented in 1878, but advanced uses such as smelting metals it was a petrol-powered four-stroke engine and providing motive power. THE REFRIGERATOR that came to power the horseless carriage. AND VACUUM FLASK A practical petrol engine was principally the work of the German Although preserving food by keeping it in engineer Gottlieb an ice-filled pit is an art some 4,000 years Daimler who developed old, the first machine capable of reducing it in 1883, fitting it temperatures was not built until 1851. first to a boat and then James Harrison, an Australian printer, in 1885 to a bicycle. noticed when cleaning type with ether However, it was another that the type became very cold as the German, Karl Benz, ether evaporated. Using this idea, he who built the first built an ether refrigerator. However, practical motor car in 1885. it was not very successful, being unable to compete with ice The diesel engine was imported all the way from America. perfected by Rudolf Diesel The first practical refrigerator, in 1897, a year which used ammonia as the before the refrigerant, was made by the invention of German scientist Karl von Linde the carburettor. [380] The petrol engine spurred the invention of the aeroplane while the jet engine, being cheaper and faster, has brought us mass worldwide air travel. The jet engine was invented by the British engineer Frank Whittle in 1930. THERMOMETERS The measurement of temperature is associated with several famous names. The first thermometer was invented in 1593 by the great Italian scientist Galileo, who is better known for his discoveries in astronomy. The instrument used the expansion and

EUREKA! contraction of a volume of gas, and was very inaccurate as well as bulky. The first thermometer to use mercury was invented by German physicist Gabriel Fahrenheit in 1714, and he also devised a temperature scale that bears his name. GUNPOWDER AND ROCKETS NUCLEAR POWER possible, and with it the release of enormous amounts of energy. This Heat also became a source of power in The basis of nuclear power was discovered information was kept secret as World War II gunpowder, the first explosive, which in 1905 by the great German-born scientist loomed, and Fermi and the other scientists appeared in China about a thousand years Albert Einstein. In his Special Theory of went to the United States. There, at the ago. Gunpowder had other uses too, and by Relativity, Einstein explained that a little prompting of Einstein, a crash programme the 1200s, rockets fuelled by gunpowder mass could theoretically be converted into to build a nuclear reactor went ahead in the were being fired in China. a lot of energy. fear that Germany might build a fission bomb first. Fermi constructed the first The first person to propose that rockets Nuclear fission is the practical experimental nuclear reactor in 1942. be used for spaceflight was not an engineer, application of Einstein’s theory, and was but a Russian schoolteacher named first achieved in the laboratory of the The first atomic bomb was tested in the Konstantin Tsiolkovsky. At the turn Italian scientist Enrico Fermi in 1934. United States in July 1945, shortly after the of the twentieth century, he realized Fermi did not realize at the time that defeat of Germany, and it was Japan that that rockets powered by liquid-fuel suffered the first, and so far the only, use of engines working in several separate fission had in fact nuclear weapons. The hydrogen bomb was stages would be required to provide occurred, and it was first tested by the United States in 1952. the immense power necessary to not until 1939 that The first nuclear reactor to produce carry people into space. However, other nuclear scientists electricity was built in Russia in 1954. Tsiolkovsky was a visionary and were able to confirm did not build rockets himself. that fission was Liquid-fuel rocket engines were [381] pioneered by the American engineer Robert Goddard, who first launched one in 1926. The first space rocket was built by the Russian engineer Sergei Korolev. It used liquid fuel to launch the first satellite, Sputnik 1, in October 1957, just a century after Tsiolkovsky was born.

WORKING WITH WAVES LIGHT AND IMAGES made the first experiments with TELESCOPES fluorescence in 1859, but it was not until People must have begun observing how 1934 that the American physicist Arthur H. Lenses had been in use for centuries before light behaves thousands of years ago. Compton developed the first fluorescent Hans Lippershey, a Dutch spectacle maker, They could see where it came from, and lamp for general use in homes and offices. happened upon the marvellous invention of they could see that it was reflected by the telescope. In 1608, he looked at a bright smooth surfaces and cast a shadow MIRRORS nearby church steeple through two lenses when something got in its way. The Greek placed one in front of the other and found philosopher Euclid was certainly familiar “Natural” mirrors made of polished that it was magnified. The working with the basic principles of optics around obsidian (a natural glass) were in use in telescopes that followed Lippershey’s 300 bce, and Alhazen, the famous Arab Turkey 7,500 years ago, but the earliest discovery all suffered from poor image scholar, wrote an important treatise on the manufactured mirrors were highly polished quality caused by the refraction of light subject in the 900s ce. But no-one knew copper, bronze and brass. Pliny the Elder through the glass lenses. Isaac Newton anything about the nature of light until mentions glass backed with tin or silver in solved this problem in 1668 by making a 1666 when Isaac Newton discovered the the first century ce, but silvering did not reflecting telescope that worked with colour spectrum and 1678 when Dutch come into widespread use until the mirrors rather than lenses. Binoculars are mathematician Christiaan Huygens Venetians found a way of doing it in the essentially two telescopes arranged side by suggested that light is composed of waves. thirteenth century. A German chemist, side. They first appeared in a Paris opera Until then, Newton’s assertion that light is Justus von Liebig, invented the modern house in 1823; although it is not known made up of particles or “corpuscles” was silvering process in 1835. Modern who invented them, they rapidly became regarded as more convincing. applications of reflecting surfaces include popular for use both indoors and outside. the periscope and the endoscope. ELECTRIC LIGHTS Periscopes were developed for use in submarines in France in 1854. The American inventor Thomas Edison is The flexible endoscope using usually credited with inventing the electric glass fibres with special coatings light. In reality, however, he was pipped at to reflect images round corners the post by a British competitor, Joseph came into use in 1958. Wilson Swan. Swan’s filament lamp, not unlike Edison’s, had been unveiled nearly a LENSES year before Edison’s in December 1878. Incandescent lamps are relatively The Roman Emperor Nero (37– inefficient compared with fluorescent 68 ce) was one of the first people to use a lamps, which give off little heat. Henri lens (although he may not have realized it) Becquerel, the discoverer of radioactivity, when he watched performances in the arena through a fragment of emerald which just happened to be of the right shape to benefit his poor eyesight. Spherical lenses used as burning glasses were certainly known by the 900s, when Alhazen described how they work. The first lenses to come into general use were convex lenses in spectacles, some- time around 1287 in Italy. The zoom lens, giving a correctly focused image at a range of focal lengths, was developed for use in the movie industry in the 1930s. [382]

EUREK MICROSCOPES with no use. After this British photographer Thomas Sutton, shaky start, the laser following a suggestion by physicist Magnifying glasses have been used as long has become one of the James Clerk Maxwell that colour as convex spectacle lenses have existed, most powerful and and they were developed into excellent adaptable tools at our might be attained by taking three single-lens microscopes by a Dutch disposal. A phenomenon black-and-white photographs merchant, Anton van Leeuwenhoek, in the that may one day bring us through three different filters, one mid-1600s. By using a tiny bead-like lens, totally realistic images – the red, one green and one blue. he was able to obtain magnifications of hologram – depends for up to 200 times. its existence on the laser. Dennis THE CAMERA Gabor invented the The origin of the compound hologram in 1947, Photography became affordable when microscope, which has two lenses, is but he could not American inventor George Eastman shrouded in some mystery. Another Dutch put his idea into brought out his Kodak camera in 1888. spectacle maker, Zacharias Janssen, has practice until It used flexible film that could go on a been credited with inventing the he had a coherent roll. For most of the 20th century, all compound microscope in 1590. However, light source, in other words a laser. cameras used film, but the rise of it seems unlikely that this would have microelectronics in the 1970s preceded the discovery of the telescope, allowed engineers to develop and Janssen’s son is thought to have light-sensitive sensors made up the story. Galileo is believed to capture images to have experimented with lenses for microscopy, but the biographers of the Dutch-born scientist Cornelius Drebbel insist that he built the first compound microscope in 1619. The first electron microscope was built over three centuries later in Germany in 1928. LASERS AND HOLOGRAMS PHOTOGRAPHY electronically, and processor The first laser was built in 1960 by Theo Photography was invented when chips to digitize Maiman of the Hughes Laboratory, USA. Joseph Niepce, a Frenchman, them. Digital cameras At the time it was scorned as the invention found a way of fixing an image have now become the norm. created in a camera obscura (“dark room” or box), a device MOVING PICTURES that had been used for many years previously as a drawing aid Two French brothers, Auguste and Louis for artists. He took his first Lumière, invented the first practical movie photograph in 1826. Niepce’s young camera and projector in 1895. At the first partner, Louis Daguerre, invented a new showings of their films, people fainted in process in 1837. Eventually it reduced the audience as a train appeared to come exposure times to under half a minute, steaming straight out of the screen into the making portrait photography hugely auditorium. Despite this impressive popular. But modern photography is based on two breakthroughs made by demonstration of its power, the brothers the British inventor William Fox-Talbot remained strangely unaware of their in 1839: the negative-positive method invention's enormous potential. When of printmaking, which allows many copies to be made someone offered them a of one exposure, and large sum of money for development of the it, Auguste thought he latent image, leading ultimately to split- was doing the eager second exposure buyer a great favour times. The first when he rejected his colour photo – of a offer. How wrong tartan ribbon – was he was! taken in 1861 by [383]

WORKING WITH WAVES PRINTING The press itself was adapted from existing THE RECORD PLAYER screw presses used in trades like book A basic form of printing was practised by binding and was so efficient that no The problems of recording sound and the Romans in the third century. About the significant changes were necessary until playing it back were solved by one of the same time Egyptian clothmakers used automation was introduced in the greatest inventors of all time, the American figures cut in blocks of wood to put marks nineteenth century. Thomas Edison. Using a tinfoil cylinder as and patterns on textiles. Block printing of books developed in isolation in both ELECTRONIC PAPER his “record” he recorded Europe and China. The Chinese produced and then reproduced the first block-printed book in 868 and In 1974, American the nursery rhyme Mary were also the first to invent movable type engineer Nicholas Had a Little Lamb on in 1041. Unlike blocks, these could be Sheridon developed 6 December 1877. He used in the printing of any book, not just the Gyricon – a called his invention a one, and were the vital element in computer screen phonograph. Ten years Gutenberg’s invention four centuries later. that could be read later Émile Berliner, a The Chinese made type out of baked clay. in bright light. German immigrant then It soon became clear that only metal type It was filled with living in Washington, could withstand repeated use. These were millions of tiny invented the flat disc first made in Korea in the early fifteenth spheres suspended record player or century. The letterpress method of printing in oil-filled gramophone. capsules. The is still in use today. spheres were dark TELECOMMUNICATIONS on one side and PAPER light on the other, Modern telecommunications have and could be effectively solved the problem of Before paper was invented, turned on by electrical signals sent by sending messages rapidly over immense people wrote on anything they the computer. Fifteen years later, Sheridon distances. Before the electronic age people could lay their hands on: silk began developing his idea into an had to use whatever methods their and bamboo in China, palm leaves alternative to paper. The first electronic ingenuity could devise, such as flashing in India, clay tablets in Babylon and book reader to incorporate the idea was mirrors and smoke signals. The Greek wax tablets in Greece. Between 3000 historian Polybius is reported to have and 2000 bce the Egyptians started using Sony’s devised a system of alphabetical smoke papyrus, a type of sedge dried into strips Librie, signals in the 100s bce, but no Polybius and then glued together in two layers to released Code is known today to rival the Morse form a sheet. Paper was invented in in 2004. Code, invented by the American Samuel China by Tsai Lun in 105 ce. In 751, Morse in 1838. Morse went on to construct the Arabs captured some Chinese the first electric telegraph, which carried papermakers at Samarkand and so the invention set out on its 400-year his code over wires similar journey to the West. Today, paper is to telephone wires. made from fibres produced by trees. In 1844, he sent the first message “What THE PRINTING PRESS hath God wrought?” The printing press was invented SOUND AND MUSIC THE by Johan Gutenberg in Germany TELEPHONE about 1450. It was one of several If archaeological discoveries are elements in the printing anything to go by, the first musical During the great days of early sound process (including movable instruments were hollow bones used engineering, inventors were often at a loss metal type) that Gutenberg as whistles in prehistoric times. Pottery to think of things to say during their was the first to perfect. drums have been found dating back experiments and demonstrations. 6,000 years. The lyre was a stringed Alexander Graham Bell, however, had no instrument played 4,500 years ago in difficulty when he used his newly invented the ancient city of Ur; it later developed telephone for the first time in 1876: “Mr into the harp. Brass instruments have Watson. Come at once. I want you” were their beginning in hollowed animal his first words. He had spilt acid from a battery down his trousers and needed help horns used to sound fanfares and from his assistant urgently. In inventing the calls. Straight trumpets over telephone, Bell had also invented two 3,000 years old were found in important devices – the microphone and Tutankhamun’s tomb, but the the loudspeaker. The mobile telephone was modern valve trumpet dates only from 1801. Probably the first man to give his name to a musical instrument was Adolphe Sax, the inventor of the saxophone in 1846. [384]

EUREKA! developed from two-way radio. The first after years of work, he successfully for most of the time. Early mobile telephone call was made in 1973 transmitted the first television picture in Bird, launched in 1965, by American engineer Martin Cooper – his attic workshop, using a boy from the was the first satellite although the first mobile networks were office downstairs as his subject. Because to solve this not commercially available until the 1980s. Baird’s system was mechanical and gave problem by Apple’s iPhone, introduced in 2007, was low picture quality, it was only a matter of keeping the first popular smartphone. time before someone came along with a exact superior electronic product. pace RADIO That someone was Vladimir Zworykin, a with The introduction of the telegraph in 1844 Russian emigrant to the solved the problem of sending messages America, who built rotation of using electricity. But the new machine the first electronic the Earth, had one big drawback: it depended on television in maintaining an a physical wire link. Other scientists 1929. The apparently immediately began working on wireless world’s first stationary position. communications. A breakthrough came in public 1888 when the German scientist Heinrich broadcast RADIO TELESCOPE Hertz discovered the existence of radio was in waves. Seven years later, Guglielmo 1936. The inventor of the radio Marconi, the 21-year old son of a wealthy telescope, and so of radio Italian landowner, made the first astronomy, was the amateur successful transmission using radio waves. American astronomer Grote Reber. He built his first receiving dish in 1937, In 1901 he created an even bigger COMMUNICATIONS SATELLITES having heard about Karl Jansky’s 1931 sensation when his radio sent a signal all discovery that the Earth is constantly the way across the Atlantic. Broadcasting The US government was responsible for being bombarded with cosmic radio began in 1906, when the Canadian developing the idea of communications waves. Reber set out to focus these waves inventor Reginald Fessenden first satellites in the 1950s. In July 1962 the with his dish and thereby map where they transmitted sound. But the invention of the American Telephone and Telegraph came from. In 1942 he made the first electronic valve or tube in the same year by Company launched Telstar, the first radio map of the Milky Way galaxy. the American Lee de Forest was the major communications satellite to transmit factor in the development of broadcasting. telephone and television signals. It could SPACE PROBES operate for only a few hours each day, because its low orbit took it out of range The first successful space probe was the of its transmitting and receiving stations Russian Luna 3, which sent back the first picture of the Moon’s unseen far side in 1959. Probing the planets became a reality in December 1962 when the US spacecraft Mariner 2 reached Venus after a 290 million-kilometre (180 million-mile) journey lasting nearly four months. TELEVISION Considering that television is the most powerful tool of mass communication known to man, it was conceived in remarkably humble circumstances. John Logie Baird was a British amateur scientist who sold shoe polish and razor blades to finance his spare-time research. In 1925,

ELECTRICITY AND AUTOMATION ELECTRICITY the electricity came not from the frog, as century Parisians for a few years that Galvani had thought, but from the metals. magnetism was a cure for certain illnesses. In about 600 bce the Greek philosopher Eventually Volta found that copper and Thales noticed that amber rubbed with zinc together produce a strong charge and MAGNETS wool somehow acquires the power to that if he built a pile of metal discs, attract light objects such as straw and alternately copper and zinc separated by The earliest magnets were made from feathers. Over 2,000 years later in 1600, pads soaked in salty water, he could naturally occurring magnetic rock called William Gilbert, physician to Queen produce a continuous electric current. magnetite. Later, when magnetite’s Elizabeth I, called this power electricity Perfected in 1800, the Voltaic pile, as it is directional properties were recognized, the after the Greek word for amber. It was not called, was the first electric battery. Since name lodestone, meaning leading stone, until the 1700s that scientists began to then, a great range of different types of was coined and it was used to make learn more about the nature of electricity, battery has been developed. magnetic compasses. Magnets did not and one of the pioneers in the field was the really come into their own until 1820 when American statesman Benjamin Franklin, THE PHOTOCOPIER the Danish physicist Hans Oersted made also an intrepid investigator. In 1752, his sensational discovery of the link Franklin daringly flew a kite in a In the 1930s Chester Carlson was working between magnetism and electricity. This thunderstorm to prove that lightning is for the patents department of a large event changed the course of human history electrical in nature. This famous electronics firm in New York. He was by making possible the great electrical experiment, in which he was lucky not to happy enough in his work except for one inventions of the nineteenth century such have been killed, led Franklin to invent the thing – the time and expense involved in as the motor, the dynamo and, in the field of lightning conductor. telecommunications, the telegraph. Franklin postulated getting patents copied. that electricity consists Eventually he became ELECTROMAGNETS of two varieties of so frustrated that he “fluid”, one positive decided to invent a The electromagnet was one of the and one negative. whole new process discoveries made possible by Oersted’s We now know that himself. The result great breakthrough. Shortly after it was the fluid is a stream was the first announced, a French scientist, André- of negative electrons, xerographic copy, Marie Ampère, proved that wires could be which were discovered taken on 22 October made to behave exactly like magnets when by the British scientist 1938. Dispensing a current was passed through them and that J.J. Thomson in 1897. with the messy wet the polarity of the magnetism depended on chemicals used in the direction of the current. So the THE BATTERY existing copiers, electromagnet – a magnet whose field is Carlson had invented produced by an electric current – was In 1780 an Italian anatomist, Luigi a dry process based on the ability of an born. Later the American inventor Joseph Galvani, noticed that the severed leg of a electrostatically charged plate to attract Henry found that wrapping several layers of dead frog could be made to twitch when powder in the image of the original touched by pieces of metal. Galvani document. Several years later the rights to concluded rightly that electricity was the process were acquired by a small family producing the reaction, but it was another firm which later grew into the mighty Italian, Alessandro Volta, who found that Xerox corporation, making Chester Carlson a very wealthy man in the process. MAGNETISM Legend has it that the phenomenon of magnetism was first observed by a Greek shepherd called Magnes when he noticed that his iron-tipped crook picked up pieces of black rock lying around on the ground. This black rock was a kind of iron ore called magnetite. Queen Elizabeth I’s physician, William Gilbert, was the first man to formulate some of the basic laws of magnetism and to speculate that the Earth itself is one big magnet. In 1644 René Descartes showed how magnetic fields could be made visible by scattering iron filings on a sheet of paper. Apart from the compass, however, no practical use for magnets was found until the invention of the electric motor – although Franz Anton Mesmer, the original mesmerizer, did manage to persuade eighteenth- [386]

EUREKA! insulated wire round a big piece of iron produced a vastly increased magnetic field. In 1829 he built the first heavy-duty working electromagnet, capable of lifting one tonne. MAGNETIC COMPASS DOMESTIC ELECTRICITY SUPPLY THE SEISMOGRAPH Chinese historians date the discovery of the In the winter of 1880 a British Historically, the Chinese have kept fuller magnetic compass to 2634 bce. Whether or industrialist, W.G. Armstrong, built a records relating to earthquakes than any not this is true, the Chinese certainly seem small hydroelectric station in the other country, so it is appropriate that they to have been the first people to discover grounds of his country mansion in should also have produced the first that magnetism could be useful in Northumberland to power its new seismograph. Invented by a mathematician, navigation, and by the third century ce electric lighting. It was the first astronomer and geographer called Chang magnetic compasses were in common use domestic electricity supply anywhere in Heng (78–139 ce), it consisted of eight in the Far East. The Chinese were not noted the world. The following winter the town carefully balanced bronze balls arranged navigators and it was left to the maritime council of Godalming in Surrey built the in a circle around a compass. Whenever nations of Europe to perfect the device. As first power station to provide electric the instrument picked up tremors from an with other inventions, the Arabs may have power for both private homes and public earthquake, one of the balls would roll off, been responsible for transmitting the idea street-lighting. Take-up however was indicating which direction the vibrations from East to West. By the eleventh century disappointingly slow and the station had had come from. The first seismograph the Vikings were using compasses on their to be closed a few years later. Some to make use of currents produced by raids in northern Europe. More recent is months later in January 1881 Thomas electromagnetism was invented by the a variation of the compass that measures Edison’s Electric Light Company installed Russian physicist Prince Boris Golitsyn the vertical angle that the Earth’s magnetic a similar station at Holborn Viaduct in in 1905. field makes at its surface. London. Unlike the Godalming scheme, this venture was highly popular and THE ELECTRIC MOTOR proved to be a roaring success. In 1821, following Oersted’s discovery the SENSORS AND DETECTORS previous year, the British scientist Michael Faraday set out to show that just as a wire Simple sensors triggered by movement carrying electric current could cause a have been in existence since ancient times. magnetized compass needle to move, so in However, devices that can sense movement reverse a magnet could cause a current- and then use this information to control carrying wire to move. Suspending a piece of wire above a bowl of mercury in which he machinery are more recent. had fixed a magnet upright, Faraday Two important early connected the wire to a battery and sure examples were invented in enough it began to rotate. He had shown the eighteenth century. that electrical energy could be converted The first was the windmill into mechanical energy, the principle fantail, invented by behind the electric motor. The American Edmund Lee in 1745, which scientist Joseph Henry built the first motor ensured that a windmill’s sails capable of work in 1830; by 1840 electric always pointed into the wind. motors were powering machinery. The second was James Watt’s centrifugal governor, which ingeniously used centrifugal force to automatically regulate the speed of a steam engine. [387]

ELECTRICI TOMATION/THE DIGITAL DOMAIN X-RAYS first radar (RAdio Detection directly to a computer’s processor, were And Ranging) system was born. developed in the 1950s. The development In 1895 German physicist Within three years radar stations of a computer screen in the 1960s made it Wilhelm Röntgen was were protecting the British coast, possible for the user to see what they were amazed to see chemicals giving the RAF a decisive edge over inputting in real time. The mouse, invented glowing on the other side of the German air force in the Battle of in the late 1960s by American engineer his laboratory while he was Britain in 1940. Douglas Engelbart, was widely available conducting experiments using a cathode by the mid-1980s, as personal computers ray tube enclosed in a container. He found AUTOMATIC TRANSMISSION rose in popularity. that the cathode ray tube was causing the glow, but not the cathode rays because they The first fully automatic transmission, the COMPUTERS could not penetrate the container. Quite by Hydramatic drive, was invented in 1939 chance he had discovered a completely by American engineer Earl A. Thompson. The first machine to process numbers unknown type of rays, which he named Following Thompson’s invention, was a mechanical calculator invented by X-rays. Before long he also discovered that automatic transmission became standard in the great French scientist Blaise Pascal in photographic plates are sensitive to the American cars. The first model to be fitted 1642 at the tender age of 19. Numbers invisible rays. This made it possible to take with the new device was a 1940 were fed into the machine by turning dials, photographs of objects not normally visible Oldsmobile. and the result appeared in a window. to the human eye, a discovery that Inside, interlocking cogs tripped one revolutionized medical diagnosis. another to calculate the result. Although it added and subtracted numbers SONAR BINARY with total accuracy, there was little need for NUMBERS such a machine at that time and it was a During World War I, German U-boat financial flop. submarines inflicted such heavy losses on The idea that Allied shipping that it became an urgent number systems do However, mechanical calculators did priority to find an effective submarine not necessarily have to develop later to perform arithmetic for detection system. After experimenting with be based on 10 is not a people. Unlike a computer, they could passive detectors, French scientist Paul recent one. Gottfried Leibniz, not store results and could not be given Langevin developed a sophisticated system working in Germany in the 1600s, instructions to perform different tasks. using ultrasonic pulses generated by developed theories of binary numbers and The idea that such a machine could be piezoelectricity. These found submarines, logic. A century later the British built occurred to the British inventor even when their engines were not running, mathematician George Boole devised a Charles Babbage in 1833, a daring insight by using echoes that bounced off their hulls. binary method of expressing logic that is that has earned him the title of “father of used in logic gates in computers. the computer”. Babbage designed such a RADAR machine, using complex arrangements of INPUT DEVICES interlocking cogs and levers to process In 1935 the British Government asked a leading scientist, Robert Watson-Watt, to Early computers received input from produce a “death ray” to knock enemy hand-operated switches or through aircraft out of the sky. Watt replied that the punched cards or punched paper tape, technology did not exist to produce a death which were produced by an operator typing into a special keyboard. Electronic ray, but that he could build a system keyboards, which could input information that would give advance warning of an air attack. The details were written down on half a sheet of paper and in just a few months the world’s [388]

EUREKA! numbers in different ways, and punched DIODES, TRANSISTORS WWW cards like those in automatic looms to AND MICROCHIPS give it instructions. It was said that the In 1989 British computer scientist Tim Analytical Engine, as it came to be called, The ancestor of these miniature Berners-Lee came up with the idea of would “weave algebraic patterns as the electronic devices was the linking documents stored on computers loom weaves flowers and leaves”. Sadly, it electronic valve or vacuum tube, in around the Internet. He and his colleague was never built. which a beam of electrons carries a current Robert Cailliau called it the “World Wide through a vacuum between electrodes Web”. By the 1990s millions of people The electronic computer, like many sealed in a glass tube. The diode (two- had begun using the Web for finding inventions, was ushered in by the pressure electrode) valve was invented by the British and sharing information. of war. It was built on Babbage’s principles scientist John Ambrose Fleming in 1904, but used speedy electronic valves (see below) followed in America by Lee de Forest’s GPS instead of slow-moving cogs and levers. three-electrode triode valve in 1906. They The first computer, called Colossus, was were crucial to the development of radio, Like the Internet, the Global Positioning built in Britain in 1943 to break enemy television, and sound recording. System began as a military project by the codes, and may well have affected the In 1948 three American scientists – US Department of Defense. It was set up outcome of World War II. Colossus was in William Shockley, John Bardeen and to enable US military units and weapons fact only used for code-cracking. The first Walter Brattain – superseded the large and to get an exact fix of their position general-purpose computer was ENIAC, an hot valve with small and cool-running anywhere in the world at any time. The 24 American machine completed in 1946. It devices made of semiconductors. GPS satellites were placed in orbit by 1993, was hot and huge, containing 19,000 valves. and the system became fully operational in These diodes and transistors were crucial 1995. GPS really took off after 2000, when DIGITAL SOUND AND IMAGES in turn to the development of digital machines, which came about with the civilian users were granted better access The method of digitizing sound known as fabrication of several devices in a single to precise military GPS signals. pulse-code modulation was invented by piece of semiconductor – the integrated British engineer Alec Reeves in 1937. circuit. This was invented by the American ROBOTS Thirty years later, Japanese engineers at the Jack Kilby in 1958 and it led to the Japan Broadcasting Corporation (NHK) microchip, into which millions of The term robot, a Czech word developed a digital audio recorder that components may be packed. The first meaning “worker”, was first applied used Reeves’ technique. It was the microprocessor was produced in 1970. to automatic machines in the 1920s. introduction of the compact disc (CD) in Robots that move themselves are much 1983 that first brought digital audio to a INTERNET older than this. They reached the height wider public. Compression, which allows of perfection in the clockwork high-quality recordings to be “compressed” The origins of the Internet go back automata of the 1700s, so they require much less space, was to 1969 when the US Department of which performed complex developed in the 1990s. The most popular Defense set up a large network of actions for the amusement form of compression is mp3; the first military computers to make the of their wealthy owners. portable mp3 player was released in 1997. country less vulnerable to enemy attack. One, for example, Universities and research organizations could write a whole With the introduction of cheap then joined the network in order to sentence. These integrated circuits in the 1970s, image exchange information, introducing early robots were entirely sensors began to replace physical film in electronic mail in the 1970s. The US driven by complex gears and cameras and video cameras. The first military separated from the network in levers. Robots have developed prototype digital camera – a 4-kilogram the 1980s, and in 1986 the routing gradually as useful machines device with a resolution of 0.01 megapixels computers of the Internet backbone have become increasingly – was built by American engineer Steven were set up in the United automatic in operation. Sasson in 1975. Digital cameras became States. Other countries available commercially by the mid-1990s. joined and companies began to connect up. The Internet has been growing ever since. [389]

TECHNICAL TERMS TECHNICAL TERMS A.C. See ALTERNATING CURRENT. ATOMS The tiny particles of which the to convert rotary motion into ACTION AND REACTION Two forces that chemical elements that make up all reciprocating motion. act whenever an object is moved. The substances are composed. An atom CAPACITOR An electrical component moving force is called the action, and the measures about a hundred-millionth of a that stores electric charge. Also called a object pushes back with a force called the centimetre (500-billionths of an inch) in condenser. reaction. Action and reaction are always size, and consists of a central nucleus CARRIER WAVE A radio wave that is equally strong, and they always push in surrounded by electrons. broadcast at a particular frequency or opposite directions. They also occur when AUGER A large screw that rotates inside a wavelength and that is modulated to carry a liquid or gas is made to move or when pipe to transport water or loose materials, a sound or picture signal. they themselves make an object move. or a screw that is used to drill holes. ADDITIVE COLOUR MIXING Combining AXLE The shaft on which a wheel turns. CATHODE An electrode with a negative light sources of the three primary colours The axle may be fixed to the wheel so charge. of light (red, green, and blue) to produce that the wheel turns when the axle rotates, CCD Charge-coupled device. A row all other colours. or, alternatively, the wheel may spin freely or array of tiny photodiodes that each AERIAL See ANTENNA. on the axle. produce an electric charge proportional to AEROFOIL The curved surface of a wing BALANCE A weighing machine, or the the intensity of light rays or infra-red rays that produces lift as the wing moves part of a mechanical watch that makes falling on the CCD. through the air. the watch keep time. CELL A single device that produces ALTERNATING CURRENT (A.C.) Electric BINARY CODE A code used in digital electric current. A battery may contain current in which the flow of current machines that consists of sequences of bits several cells connected together, and a constantly reverses direction. making up binary numbers. The code solar panel may contain several solar cells. AMPÈRE (AMP) The unit of measurement represents data or programs. Also a unit of memory that stores one bit for electric currents. A 1-amp current BINARY NUMBER A number in the binary of binary code. flows through a circuit if the resistance is system, which contains only two digits or CENTRIFUGAL A word applied to any 1 ohm and the voltage 1 volt. numerals, 0 and 1. From the right-hand rotating device or part that moves away AMPLITUDE The amount of energy in a end of the number, each successive digit from the centre of rotation. ray or wave. It is equal to the change in signifies the presence (1) or absence (0) CHIP See MICROCHIP. energy (for example, pressure in a sound of 1, 2, 4, 8 and so on, doubling each CIRCUIT A source of electric current and wave) that takes place as one complete time. The binary number 1101 indicates a set of electrical devices or components wave passes. 1x8 + 1x4 + 0x2 + 1 x1, which is connected together by wires so that current ANALOG A kind of machine or system equivalent to the decimal number 13. flows through them. A circuit board that works with, or produces, a quantity BIT Short for binary digit. A digit or contains a printed metal pattern to conduct that may vary in level. A glass numeral in a binary number, written as current to components fixed to the board. thermometer, in which the temperature is 1 or 0. In a digital machine, bits take a CLOCK In a calculator or computer, a indicated by the level of a rising or falling physical form such as a sequence of on-off device that produces regular electric column of liquid, is an analog device. pulses of electric current in a wire or pulses which synchronize the operations Many analog machines and systems work black bars and white spaces in a barcode. of the components. with an electric signal that varies in voltage. Sets of bits represent things such as COG A toothed gear wheel or a tooth on The analog signal often represents the numbers or amounts, words, sounds, such a wheel. varying sound waves in speech or music, and images. COMBUSTION Burning. A chemical and the varying light rays in an image. BLUETOOTH A radio signal that allows reaction that involves combining with ANODE An electrode with a positive digital devices to connect wirelessly over oxygen, producing light and heat. charge. short distances. CONCAVE A word applied to a surface ANTENNA A part of a radio transmitter or BOOM The arm of a crane or excavator that curves inwards at the centre. receiver that sends out or picks up radio that raises the load. CONDENSER In heat, a device that cools waves. Also called the aerial. BYTE A binary number containing eight a gas or vapour so that it changes into a ARMATURE A part of an electric machine bits. It represents decimal numbers from 0 liquid. In electricity, a component (also that moves in response to a current or (00000000) to 255 (11111111). called a capacitor) that stores electric signal, or that moves to produce a current CAM A non-circular wheel that rotates charge. or signal. in contact with a part called a follower. Together, the cam and follower are used [390]

TECHNICAL TERMS CONVEX A word applied to a surface that to represent things such as amounts, high and low or off – to represent the two curves outwards at its centre. words, sounds, and images. The numbers digits in the sequence of bits that make COUNTERWEIGHT A weight that is fixed are in binary code. up the signal. to one part of a machine to balance the DIODE An electronic component ELECTRODE Part of an electrical device weight of a load elsewhere in the machine. through which current can flow in or machine that either produces electrons CPU Central processing unit. An only one direction. A photodiode is (cathode) or receives electrons (anode). integrated circuit that acts as the “brains” sensitive to light or other rays, and ELECTROLYTE A solution, paste, or of a digital device – carrying out all a light emitting diode (LED) emits light molten substance that conducts electric computation, following the instructions or other rays when a current flows current between electrodes. of computer programs, and reading and through it. ELECTROMAGNET A device that uses an writing the memory. DIRECT CURRENT (D.C.) Electric electric current to produce a magnetic field. CRANK A wheel or rotating shaft to current that always flows in one direction. ELECTROMAGNETIC WAVES The family which a pivoted connecting rod is DRAG The force with which air or water of rays and waves that includes radio attached. As the crank turns, the rod resists the motion of an object such as a waves, microwaves, infra-red waves, light moves to and fro; alternatively, the rod’s car, boat, or aircraft. Drag is also called rays, ultraviolet rays, X-rays, and gamma movement may turn the crank. In a car air resistance or water resistance. rays. All consist of vibrating electric and engine crankshaft, a number of cranks are ECCENTRIC A word applied to any magnetic fields and travel at 300,000 linked together and turned by rods object, often a wheel, that rotates about a kilometres a second (186,000 miles per connected to the pistons. A winding point other than its centre. An eccentric second) which is the speed of light. All handle is also a form of crank. pin is an off-centre projection on a wheel. the rays and waves differ only in their DAMPER A part of a machine that absorbs It slides in a slot on an arm so that as the wavelength or frequency. Except for vibration or prevents sudden movement. wheel rotates, it drives the arm to and fro. gamma rays, all electromagnetic waves In a piano, the mechanism that stops the EFFORT The force that is applied to a are generated by accelerating electrons. piano wires sounding. machine to produce an action. ELECTROMAGNETISM The relationship DATA Information of any kind that can ELASTICITY The ability of certain between electricity and magnetism; either be fed into a computer or other digital materials to regain their former shape can be used to produce the other. machine, which stores and processes the and dimensions when forces cease to ELECTRON The smallest particle in an data in the form of bits. Data mainly act on them. atom. An electron is about 100,000 times consists of numbers or amounts, words, ELECTRIC CHARGE The electrical smaller than an atom, and has a negative sounds, and images. property produced by the addition electric charge. Electrons surround the D.C. See DIRECT CURRENT. (negative charge) or removal (positive central nucleus of the atom. They may DENSITY The weight of any amount of a charge) of electrons. The charge on the be freed from atoms to flow through a solid, liquid, or gas relative to its volume. electron is the fundamental unit of conductor in an electric current, or to Every pure substance has a particular electricity. move through a vacuum in an electron density. Provided that two substances do ELECTRIC CURRENT The continual flow beam. Electrons also move to produce a not mix, the one with the lesser density of electrons through a wire or other charge of static electricity. will always float on top of the other. electrical conductor. ELECTROSTATIC A word applied to a Wood floats on water because it has a ELECTRIC FIELD The region around an device that works by the production of lesser density than water. electric charge. One field affects another an electric charge. DIFFRACTION The bending of rays or so that a negative charge and positive ELEMENT A substance containing only waves that occurs as they pass through charge attract each other, and two negative one kind of atom. Some elements, such as an opening or around an edge. The angle charges or two positive charges repel hydrogen, nitrogen, oxygen, and chlorine, of bending depends on the wavelength. each other. are gases at normal temperatures. Others, DIGIT A single numeral in a number, ELECTRIC SIGNAL A flow of electric such as iodine, sulphur, and most metals, for example 2 or 7 in 27. The decimal current that causes a machine or system including iron, aluminium, copper, silver, number system uses ten different digits to operate in a particular way. A and gold, are solids. Only two, bromine (0 to 9), the binary number system two microphone produces an electrical signal and mercury, are liquids. Just over 100 different digits (0 and 1). that represents the sound waves entering elements are known, including several DIGITAL A kind of machine or system it, and the sound signal goes to a artificial elements such as plutonium. All that works with or produces numbers. loudspeaker to reproduce the sound. other substances are compounds of two A digital thermometer measures the There are two kinds of electric signals. In or more elements. temperature and displays it as a number an analog signal, the voltage varies in level E-MAIL Electronic mail. A message that of degrees. Computers and many other and may have any value. In a digital is sent from one computer to another. digital machines and systems use numbers signal, the voltage has only two levels – It may contain data, such as a document, sound or image, or computer programs. [391]

TECHNICAL TERMS ENERGY The capacity to do work. Every electromagnetic waves such as radio waves expansion of a gas, which is either steam action that occurs requires energy and and light rays. Also the rate at which an or the products of burning a fuel. There converts one form of energy into another. alternating current changes direction, are two main kinds: external and internal Forms of energy include movement, heat, flowing forwards and then backwards. combustion engines. In an external light and other electromagnetic waves, Frequency is measured in hertz (Hz), combustion engine, the source of heat that sound and electricity. There are also stored which is the number of waves or forward­ raises the temperature of the gas is outside or potential forms of energy, such as backward cycles per second. the engine, as in the boiler of a steam chemical energy, that are available for FRICTION A force that appears when a engine. In an internal combustion engine, conversion into other forms. solid object rubs against another, or when fuel burns inside the engine. Petrol and ESCAPEMENT The part of a mechanical it moves through a liquid or gas. Friction diesel engines, jet engines and rocket clock or watch that connects the train of always opposes movement, and it engines are all internal combustion engines. gear wheels, which moves the hands, to disappears when movement ceases. HEAT EXCHANGER A device in which the pendulum or to the balance, which FULCRUM The pivot on which a device heat is taken from a hot liquid or gas in controls the hands’ speed. such as a lever is supported so that it can order to warm a cool liquid or gas. Inside EVAPORATION The process by which balance, tilt, or swing. a heat exchanger, the pipes containing a liquid turns into a vapour at a FUSION A nuclear reaction in which the the hot fluid generally pass through the temperature below its boiling point. nuclei of atoms combine to produce cool fluid. Evaporation occurs if the pressure of the energy. HELICAL A word applied to any device in vapour above the liquid is low enough for GAMMA RAYS Invisible high­energy the shape of a helix, such as a coil spring molecules to escape from the liquid into electromagnetic waves with wavelengths or a corkscrew. the vapour. shorter than about a hundred­billionth of HOLE A space in an atom produced by FIBRE OPTICS Devices that send images a metre. Gamma rays are emitted by the the removal of an electron. As an electron or light signals along glass fibres (optical nuclei of atoms. comes from another atom to fill the hole, fibres). the hole “transfers” to the other atom. FILE A set of data for use by a computer. GAS TURBINE A heat engine in which HOLOGRAM An image formed by laser It may consist of a list, document, image, fuel burns to heat air and the hot air light that appears to have depth like a real piece of music and so on. File transfer is and waste gases drive a turbine. The jet object, or the photographic film or plate the sending of files from one computer to engine is a gas turbine. Helicopters may that produces the image. another. have gas turbines in which the turbine IMAGE A picture of an object or scene FISSION A nuclear reaction in which the drives the rotor. formed by an optical instrument. A real nuclei of atoms split apart to produce GEAR Two toothed wheels that intermesh image can form on a screen or other energy. either directly or through a chain so that surface. A virtual image can be seen only FLUORESCENT A word often applied one wheel turns to drive the other. A in a lens, mirror or other instrument, or to something that glows with light. A screw called a worm or a toothed shaft a hologram. Images are recorded by fluorescent object, such as a screen, called a rack may replace one of the wheels. photography, printing, video recording changes an invisible electron beam or In a moving machine such as a car or and holography, and can be stored in ultraviolet rays into visible light. bicycle, a gear is also a combination of memory units. FOCUS A point at which rays or waves gear wheels that produces a certain speed. IMAGE SENSOR A chip containing meet. With lenses, a sharp image forms Top gear gives a high speed, and low gear millions of light­sensitive elements that at the focus of the lens. The focus of a a slow speed. record the exact amount of light that falls telescope is the position at which an GIGABYTE (GB) 1,073,741,824 bytes. onto it. A CCD is a type of image sensor. image is produced. GRAVITY The force that gives everything INCANDESCENT Describes light emitted FORCE The push or pull that makes weight and pulls objects towards the as a result of something being heated. something move, slows it down or stops ground. The normal pressure of the air INCLINED PLANE A sloping surface. it, or the pressure that something exerts or water is caused by gravity. An inclined plane can be used to alter on an object. When a force acts on an HAIRSPRING A flat spring in which one the effort and distance involved in doing object, it may be split into two smaller end is fixed and the other end can move. work, such as raising loads. component forces acting at different HARMONICS A set of accompanying INDUCTION The production of angles. One of these component forces waves that occurs with a main or magnetism or an electric current in may move the object forwards in one fundamental wave. The frequencies of the a material by a magnetic field. direction, while the other component may harmonics are multiples of the frequency INERTIA The resistance of a moving support its weight or overcome a separate of the fundamental wave. object to a change in its speed or force acting in another direction. HEAT ENGINE An engine in which heat direction, and the resistance of a FREQUENCY The rate at which waves is converted into movement by the stationary object to being moved. of energy pass in sound waves and [392]

TECHNICAL TERMS INFRA-RED RAYS Invisible to movement that a machine has to further fission, and must be slowed to electromagnetic waves with wavelengths overcome. promote fission in the fuel. longer than light rays and ranging from a LOGIC GATE A miniature device within MODULATION Superimposing one kind millionth to a thousandth of a metre. the processor of a digital machine that of wave on another so that the first wave They include heat rays. takes part in the processing of bits. It changes the second, often varying its INTERFERENCE The effects produced performs a certain logical operation. An amplitude (AM) or frequency (FM). when two waves or rays meet. The OR gate, for example, opens to pass a bit if MOLECULES The minute particles of combined wave has a different frequency the first or second of two control bits is an which all materials – solids, liquids, and or amplitude, giving colour effects in light, on-bit (binary 1). gases – are composed. Each material has for example. MAGNETIC FIELD The region around a its own kind of molecules, which each INTERNAL COMBUSTION ENGINE magnet or an electric current that attracts consist of a particular combination of See HEAT ENGINE. or repels other magnets. atoms. Water, for example, contains INTERNET The global network of MAINS SUPPLY The supply of electricity molecules each made of two hydrogen interconnected computer networks. to the home. It is alternating current at a atoms fixed to an oxygen atom. In ION An atom that has lost or gained voltage of about 240 volts and a frequency crystals, the atoms connect together in one or more electrons and has an of 50 hertz. a regular network rather than forming electric charge. MASS The amount of substance that an separate molecules. JACK A device that raises a heavy object object possesses. Mass is not the same as N-TYPE SEMICONDUCTOR A kind of a short distance, with reduced effort. weight, which is the force that gravity semiconductor that has been treated to KILOBYTE (KB) 1024 bytes. exerts on an object to pull it to the produce electrons. It tends to lose these LASER A device that produces a narrow ground. A floating object loses weight, electrons and thus gain a positive charge. beam of very bright light or infra-red rays, but its mass remains the same. NEGATIVE In photography, an image in in which all the waves have exactly the MEGABYTE (MB) 1,048,576 bytes. which the brightness is reversed so that same frequency, are in phase and move MEMORY UNIT The unit in a digital black becomes white and vice-versa; in a exactly together. Laser stands for Light machine or system that stores the bits colour negative, colours are reversed so Amplification by Stimulated Emission making up data or programs. that primary colours become secondary of Radiation. MICROCHIP An electronic component colours and vice-versa – blue becomes LCD Liquid crystal display. A display containing many miniature circuits that yellow, for example. In electricity, the screen commonly used in televisions, can process or store digital electric signals. charge on an electron is considered to be computers, tablets, smartphones, and Also called a chip or integrated circuit. negative, so anything that stores or emits other digital devices. MICROPROCESSOR A microchip that electrons is also negative. In waves, a LED Light-emitting diode. A diode that holds the CPU of a digital device. minimum or opposite value of energy emits a beam of light or infra-red rays MICROWAVES Radio waves with very is considered to be negative. when fed with an electric current. short wavelengths ranging from a NEUTRON One of two kinds of particles LENS A device that bends light rays to millimetre to 30 centimetres. that make up the nucleus of an atom. form an image. MIRROR A smooth surface that reflects The other kind is the proton. A neutron LEVER A rod that tilts about a pivot to light rays striking it. A semi-silvered mirror has almost the same mass as a proton but produce a useful movement. partly reflects and partly passes light. no electrical charge. All nuclei contain LIFT The upward force produced by an MODEM A device that connects a digital neutrons except the very lightest, which aircraft wing and helicopter rotor, and machine via the telephone network to is the common form of hydrogen. by the foils of a hydrofoil. another machine. It changes the outgoing Deuterium and tritium, which are the LIGHT RAYS Visible electromagnetic digital signal into a sound signal that can other forms or isotopes of hydrogen, waves ranging from 4 to 8 ten-millionths be sent over a telephone line, and do contain neutrons. of a metre in wavelength, and respectively converts an incoming sound signal back NUCLEUS (pl. NUCLEI) The central part from blue to red in colour. into a digital signal. It does this by of an atom, composed mainly of two LINEAR MOTION Movement in a modulation and demodulation, and the smaller particles called protons and straight line. name modem is short for modulator- neutrons that are held together with great LOAD The weight of an object that is demodulator. force. The nucleus is about 10,000 times moved by a machine, or the resistance MODERATOR A substance used in a smaller than the whole atom. It is nuclear reactor to slow the fast-moving surrounded by electrons. neutrons produced by fission of uranium OPTICAL FIBRE See FIBRE OPTICS. fuel. Fast-moving neutrons do not cause OSCILLATOR A device that produces sound waves or an electric signal of regular frequency. P-TYPE SEMICONDUCTOR A kind of [393]

TECHNICAL TERMS semiconductor that has been treated to PROPELLANT The liquid in a spray can the pawl engages the teeth of the ratchet produce holes (spaces for electrons). It or aerosol can which produces pressure to prevent movement. A pawl may also tends to gain electrons and thus acquire that creates the spray, or the fuel of a move to and fro to turn a ratchet wheel a negative charge. rocket engine. in one direction. PAWL A pivoted arm that engages with PROTON One of two kinds of particles RAY An electromagnetic wave with a the teeth of a ratchet. that make up the nucleus of an atom. short wavelength. PENDULUM A rod or cord with a heavy The other kind is the neutron. A proton REACTION The equal and opposing force weight called a bob attached to the lower has almost 2,000 times the mass of an that always accompanies the action of a end. The pendulum pivots at the upper electron and has a positive electric charge. force (see ACTION AND REACTION). Also, end and the bob swings to and fro. The The number of protons in the nucleus in chemistry, the process by which one time of each swing depends only on the defines the identity of an element. or more substances change to become length of the pendulum – not on the Hydrogen, for example, has one proton different substances. Chemical reactions weight of the bob. per nucleus, while oxygen has eight. often involve the production or PINION The smaller of two gear wheels, PULLEY A wheel over which a rope, consumption of heat. In chemical or a gear wheel that drives or is driven by chain or belt passes. reactions, the atoms involved recombine a toothed rack. PULSE A short burst of electric current. in different configurations but do not PIXEL Picture element. A tiny part of an RACK A toothed shaft that intermeshes themselves change. In nuclear reactions, image on a screen. The sharpness or with a pinion. the central nuclei of the atoms do change, resolution of the image depends on the RADIATION The electromagnetic rays producing new elements and emitting number of pixels, often called dots, in that come from any source of heat, or the energy in the form of heat or radiation. the image. rays and streams of particles that come RECIPROCATING MOTION Movement PLANET WHEEL A gear wheel that moves from nuclear reactions and radioactive in which an object moves repeatedly around another gear wheel, the sun wheel, materials. Heat rays are harmless (unless forwards and backwards. as it turns. they burn), but nuclear radiation can be REFLECTION The reversal of direction POSITIVE In photography, an image that highly damaging to living cells. that occurs when a wave or ray bounces looks like the original scene. In electricity, RADIATOR The part of a car engine off a surface. Internal reflection occurs if anything that receives electrons or from which removes heat from the cooling light rays reflect from the inner surface which electrons have been removed. water that circulates through the engine; of a transparent material. PRECESSION A movement of a rotating also a heater that warms a room by REFRACTION The bending of a wave wheel in response to a force on its axle. radiating (emitting) heat rays. or ray that occurs as it passes from one Precession makes the wheel move at right RADIOACTIVITY The production of medium or substance into another, for angles to the direction of this force. radiation by materials containing atoms example from air into glass. PRESSURE The force with which a liquid with unstable nuclei, such as nuclear RESISTANCE In mechanical machines, or a gas pushes against its container or fallout and the waste from nuclear reactors. a force that slows the movement of an any surface inside the liquid or gas. Units RADIO WAVES Invisible electromagnetic object, such as air resistance and water of pressure measure the force acting on a waves with wavelengths ranging from a resistance, and the resistance of a material unit of surface area. millimetre to several kilometres. Radio to cutting or breaking. In electricity, the PRIMARY COLOUR A colour that cannot waves used for radar have wavelengths of property of an object, measured in ohms, be formed by mixing other colours. All several millimetres or centimetres, shorter that obstructs the flow of electrons other colours can be made by combining than the waves used for broadcasting through it. two or three primary colours. sound radio and television. RESONANCE The production of PRISM A glass block with flat sides in RAM In mechanical machines, such as vibrations or sound at a certain natural which light rays are reflected from the an excavator, a device that exerts a strong frequency in an object when it is struck inner surfaces. pushing or pulling force. In digital by external vibrations or sound waves. PROCESSOR The unit in a digital machine machines, random-access memory – a REVOLUTION One complete turn of a that processes data in accordance with the memory unit in which programs and data rotating object. instructions of a program. are held temporarily and can be changed. ROM Read-only memory. A memory PROGRAM A set of instructions that RATCHET A device that allows movement unit in digital machines in which causes a digital machine to perform a in one direction but not in the other. A programs and data are stored permanently particular task. The instructions are in ratchet has a toothed shaft or wheel on and cannot be changed. binary code. which a pawl rests. The pawl is pivoted ROTARY MOTION Movement in which so that it can move over the teeth of the an object spins around. ratchet in one direction. If the pawl or SCALE A set of units or an indicator ratchet moves in the reverse direction, [394]

TECHNICAL TERMS marked with units for measuring. A SUBTRACTIVE COLOUR MIXING VALVE A device that opens or closes to weighing machine is also known as a Combining dyes or pigments of the three control the flow of a liquid or gas through scale or scales. secondary colours of light (yellow, cyan, a pipe. Valves often work one way and SCANNING The conversion of an image and magenta) to produce all other colours. seal a container so that a liquid or gas can into a sequence of electric signals. These colours mix by absorbing primary only enter it and not escape. Scanning splits up the image into a colours from the light illuminating the VAPOUR See EVAPORATION. series of horizontal lines and converts dyes or pigments. VOLTAGE The force, measured in volts, the various levels of brightness and SUN WHEEL A gear wheel around which with which a source of electric current colours in each line into signals. Also a planet wheel rotates. or charge moves electrons. the process in which a microchip in a SUPERCONDUCTIVITY The removal of WATT The unit of power. One watt is keyboard or keypad continually sends electrical resistance in a conductor by produced when a current of one amp from a signal to all the keys to detect when cooling it. The conductor can then pass a a source of one volt flows for one second. one is pressed. very large electric current and generate WAVE A flow of energy in which the level SCREW A shaft with a helical thread a strong magnetic field. of energy regularly increases and decreases, or groove that turns either to move itself, SUPERSONIC Faster than the speed of like the height of a passing water wave. or to move an object or material sound, which is about 1200 km/h One complete wave is the amount of flow surrounding it. (760 mph) at sea level. between one maximum of energy and the SECONDARY COLOUR A colour formed TENSION The force produced in a bar next. This distance is the wavelength. by mixing two primary colours. or a rope or string when it is stretched. WAVELENGTH See WAVE. SEMICONDUCTOR A substance, such as TERMINAL The part of an electric WEBSITE A set of pages (screen displays) silicon, whose electrical properties can be machine to which a wire is connected of information stored in a computer that precisely controlled to regulate the flow to take or supply electric current. can be freely accessed by any other of electrons and handle electric signals. THREAD The helical groove around a computer. SHAFT A bar or rod that moves or turns screw or inside a nut. WEDGE A part of a machine with a sloping to transmit motion in a machine. Also a THRUST A force that moves something side that moves to exert force. deep hole, as in a lift shaft. forwards. WEIGHT The force with which gravity SOFTWARE In general, the programs that THRUSTER A propeller used for pulls on an object. make digital machines carry out tasks. manoeuvring a ship or submersible; also WHEEL Any circular rotating part in a SOLAR CELL A device that converts light a small rocket engine or gas jet used for machine. into electricity. manoeuvring a spacecraft. WHEEL AND AXLE A class of rotating SOUND WAVE Waves of pressure that TRANSFORMER A device that increases machines or devices in which effort applied travel through air and other materials. or decreases the voltage of an electric to one part produces a useful movement at At frequencies from about 20 hertz up current. another part. to 20,000 hertz, we can hear these waves TRANSISTOR An electronic component WI-FI Technology that allows digital as sound. made of sections of n-type and p-type devices within a particular location to SPEED The rate at which something semiconductor that switches a current communicate with each other or connect moves. Also a combination of gear wheels. on or off, or amplifies the current. A to the Internet using radio waves. SPROCKET A toothed wheel over which controlling signal goes to the central WINCH A drum around which a rope is a chain passes. section (the base or gate), which controls wound to pull, lift, or lower an object. STATIC ELECTRICITY Electric charge the flow of current through two outer WORLD WIDE WEB The system of produced by the movement of electrons sections (the emitter or source, and the interconnected web sites accessed via into or out of an object. collector or drain). the Internet. STEREOPHONIC SOUND Sound TURBINE A machine with blades that are WORM A screw that intermeshes with reproduced by two loudspeakers or turned by the movement of a liquid or gas a gear wheel. earphones in which the sound sources, such as air, steam, or water. The turbine X-RAYS Invisible electromagnetic waves such as voices or instruments, are in may also turn to move the liquid or gas. with wavelengths shorter than light and different positions. ULTRAVIOLET LIGHT Invisible ranging from 5 billionths to 6 million- STEREOSCOPIC IMAGE An image with electromagnetic waves with a wavelength millionths of a metre. depth. This kind of image is formed by a less than that of light and ranging from 5 pair of images of an object or scene seen billionths to 4 ten-millionths of a metre. separately by both eyes. [395]

INDEX INDEX light 182, 198 car 86, 158, 159 window winder 39 A scanning 297, 304 hydraulic 127, 128 windscreen wipers 49 X-rays 297, 304 power 127, 130 cash machine 316, 332, 336 accelerometer 118, 240, 241, augers 66-9 Brattain, Walter 389 Cassegrain focus 190, 191, 251 293, 367 automatic door 305 breath tester 294 catalytic converter 156, 157 automatic machines 291, 389 buoyancy 96, 97, 104 cathode 296 action and reaction, 100, 101, automatic transmission, car burglar alarm 277, 305 cathode ray tube 388 106, 137, 164 306-9, 388 burner, hot-air balloon 105 Cayley, Sir George 378 autopilot 291, 293 burning 146-7, 156, 162, 164, CCD (charge-coupled device) actuators 366 axe 14 166 327 address bus 344 axles 30-3, 70, 375 buses, computer 344 CD-ROM 201 aerial, radar 300, 301 bus, spacecraft 252 centrifugal force 39, 71, 74, 75, B Bushnell, David 378 125, 306 telecommunications 244, 250 button battery 268 centrifugal pump 125 aerofoil 100, 103, 106, 107, Babbage, Charles 388-9 byte 316, 332, 335 chain hoist 56 baggage scanner 297 chain reaction, nuclear fission 114, 119, 378 Baird, John Logie 385 C 168, 170 aerosol 138 balance, weighing machine charge, electric 220, 241, 58, Agricola 376 calculator 194, 271, 361, 388 262, 264, 267, 315, 331 aileron 108, 109, 112-13 19, 22, 24 calibrating plate, scales 24, 25 Charles, Jacques 378 air: barometer 134 ball-point pen 141 camera 190, 383 circuit, electric 240, 267, 328 ballast tanks 96, 97 circuit breaker 286 flight 106-18 balloon 94, 105, 378 colour photography 204, 206, clocks 42, 79, 265, 375 floating 104-5 banking, online 351 325, 383 clutch 40, 84-5 pneumatic machines 126-7 barcode 331, 337, 370 digital camera 118, 203, cochlea 219 pressure 120, 127, 132, 134, Bardeen, John 389 204-5, 318, 319, 326, 332, Cockerell, Christopher 379 379 barometer 134 369, 389 coil springs 80, 81, 377 suction 120, 130 bathroom scales 24 drone 118 coils: electromagnetism 175, air bag 292 batteries 230, 259, 265, 267, film 202, 383, 389 252, 265, 275, 276, 281, 283, air cleaner 262 lenses 188, 205, 206 284, 302 air conditioner 153 268-9, 386 movie 206, 209, 383 transformers 285 air hammer 127 camera 203 single-lens reflex 204-5, 383 colours 184-5 aircraft 108-18 cars 158, 159, 269, 288 television 206 colour printer 360 artificial horizon 77 computers 268 video 206–7, 367, 389 colour spectrum 382 autopilot 291, 293 e-reader 221 cams 48-53, 376 computer screen 221, 247 flight 106-11, 114-18 beam scales 22 can opener 15, 374 digital images 206, 215, 247, flight simulator 365 bearings 35, 82, 88, 114, 377 candle 182, 183 325 helicopters 106, 114-18, 379 Becquerel, Henri 382 canoe 378 photography 202-3 history 378 Bell, Alexander Graham 384 capacitor 228, 246, 263, 264, primary 184-5, 325 jet engine 108, 162-3, 380 bell, electric 278 333 printing 210-11, 214-15, 216 radar 300-1 belts 36-7, 212, 234, 375 capillary action 141 scanning 214, 326-7 airliner 111, 112-13, 162 Benz, Karl 376, 380 carburettor 140-1 secondary 184 airport detector 302 Berliner, Émile 384 Carlson, Chester 386 combine harvester 68-9, airship 104, 378 Bernoulli, Daniel 378 carrier signal, radio 242, 244 376 alarm systems 277, 291, 295, Bessemer, Henry 380 cars: air bag 292 combustion 146-8, 164, 166, 305 bevel gears 34, 37, 44, 45, 66 automatic transmission 182 alcohol, breath tester 294 bicycle 28, 38, 70, 377 306-9, 388 combustion chamber, rocket Alhazen 382 bimetal thermostat 154, 270 battery 158, 159, 269, 288 engine 165 alphanumeric display 361 binary numbers 201, 203, 214, brakes 86, 127, 128, 158, 159 communications: digital 348-55 alternating current 267, 281, 242, 257, 272, 273, 206, 315, cams and cranks 49-51 dish 250, 252 293 388 carburettor 140-1 satellites 248-9, 385 Ampère, André-Marie 386 binoculars 192, 382 clutch 84-5 space probes 252-3 amplifier 228, 229, 230-1, 234, bits: making 315-27 cooling system 125, 152-3, telecommunications 236-53, 235, 239, 243, 362 processing 338-45 154 384 amplitude modulation (AM) sending 200, 201, 346-55 cruise control 309 telescopes 250-1 242 storing 328-37 differential 40, 45 commutator 281, 284 analog-digital converter (ADC) using 357-71 electric horn 279 compact disc (CD) 201, 331, 322, 323, 324, 325, 327, 328 blast furnace 148-9, 380 engine 156-7, 158, 159 332, 389 anchor escapement 42 block and tackle 57 gearbox 308-9 comparator-register 322 aneroid barometer 134 Blu-ray player 200-1 hybrid 158-9 compass 77, 276, 387 anti-roll bar 81 Bluetooth 317, 319, 328, 368 ignition system 288-9 compressed air 126-7 aqualung 131, 379 boats 94-5, 98-101, 103, 119, lubrication 88 compression: digital 206, 207, Archimedes 374, 376, 378 378 oil pump 124 324, 389 Ariane 5 rocket 165 body scanner 303, 304 seat belt 75 sound waves 222, 228, 231, Armstrong, W.G. 387 bomb, nuclear 170, 381 speedometer 46 242, 324 artificial horizon 77 bookbinding 218-19 starter motor 73 video 206, 207 astronomy: radio telescope Boole, George 388 steering 43, 129 compressor 129, 152, 153, 162 250, 385 Booth, Hubert 379 suspension 80-1 Compton, Arthur 382 space probes 252-3 bottle opener 22 synchromesh 85 computer 368-9, 388-9 telescopes 190-1, 250-1, 382 Bourdon gauge 134 temperature gauge 270 animation, 3D 209 atom bomb 170, 381 bow thruster 98 thermostat 154 cars 158, 159 atoms 92, 93 brace and bit 32, 66 tyre 83 electricity 258, 259 brakes: bicycle 28 heat 150, 182 [396]

INDEX CD-ROM 201 destructive interference 198 Edison, Thomas 382, 384, 387 evaporation 152, 153 digital sound 324 detectors 290-309 effort: inclined plane 10 excavator 23 disk drive 332, 335 deuterium 169, 170, 174, 175 exhaust, petrol engine 157 e-mail 350-1 Dewar, James 380 levers 18-23 explosives 147, 170, 381 flight 108, 365 diaphragm pump 123 pulleys 54-5 eyesight 180 Internet 350-1, 352, 389 Diesel, Rudolf 380 egg whisk 44, 46 keyboard 317, 344 diesel engine 140, 156, 158, Einstein, Albert 381 F magnetic storage 333-5 elasticity, springs 79 memory 329-37 380 electric bell 278 Fahrenheit, Gabriel 381 microchip 342-3 differential 40, 45, 375 electric car 158, 159 fallout, radioactive 170, 171 modem 350 diffraction 199 electric drill 66 Faraday, Michael 387 mouse 318-19 digital-analog converter (DAC) electric guitar 229 Farman, Henry 378 network 349, 351, 370-1 electric heat 150-1 feed-dog, sewing machine 53 printer 282, 360-1 322, 324, 362 electric horn 279 feedback mechanisms 291, 309 processing bits 338-45 digital camera 118, 203, 204-5, electric keyboard 228, 316 Fermi, Enrico 381 robot 366-7 electric light 382 Fessenden, Reginald 385 scanner 214, 326-7 318, 319, 326, 332, 369, 389 electric mixer 46 fibre optics 187, 196, 238, 350, smartphone 240-1, 320, 321, digital images 203, 206, 215, electric motor 280-1, 387 334, 350, 363, 385 electricity 256-73, 386 351 software 201, 214, 215, 240, 247, 253, 325 batteries, 268-9, 386 fibre-tip pen 141 282, 354, 368 digital machines 315-73 circuits 240, 267, 328 films: movie 206, 383 speech recognition 363 current 259, 266-7 supermarket checkout 370-1 bits 315-28 digital machines 315 photography 202, 297 ultrasound 299 processing bits 338-45 generator 284-5 filter, polarizing 194, 209, 246, video games console 328 sending bits 346-55 hydroelectric turbine 33 virtual reality 364 storing bits 329-37 piezoelectricity 264-5 247 concave lenses 188, 189 using bits 356-71 power supply 284-5, 387 fire 380 condenser microphone 228 digital micromirror device solar cell 267, 271 fire engine 379 conduction 142, 143, 145, 150 (DMD) 208 static 258, 261 fire extinguisher 139 conductors 259, 262-3 digital radio 244 transformer 285 firework rocket 164 constant-mesh wheels, gearbox digital recording 196, 389 two-way switch 286-7 fishing rod 21, 23 40 digital sound 324, 362, 389 wind turbine 35 fission, nuclear 168, 170 constructive interference 198 digital still camera 118, 203, electrodes 182, 194, 195, 220, flaps, airliner wing 108, 112-13 contact lenses 188 204-5, 318, 319, 326, 332 268 flare 147 controls, automatic 257 digital television 206 electrolyte 268 flash memory 334 convection 142, 143 digital thermometer 322 electromagnet 151, 265, 275, Fleming, John Ambrose 389 convex lenses 188, 189 digital video 206-7, 208, 332 276, 277, 278, 279, 281, 283, flight 106-18, 378 cooling system 125, 152-3, 154 digital versatile disc (DVD) 284, 304, 309, 386 flight simulator 365 corkscrew 43, 64 201, 337 electromagnetism 192, 239, float chamber, carburettor 140 Cornu, Paul 379 diode 263, 272, 389 275-89, 302-3, 386-7 floating 94-119, 378 Coude focus 188 dip pen 141 electron microscope 193, 383 fluorescent lamp 182, 183 counter: distance 38, 46 direct current 267, 281 electronic ink 220, 221 flywheel 72, 73, 84, 288, 308 water meter 135 motor 281 electronic music 228-9 focussing screen 204 counterweights 56-61 disc brakes 86 electronic scales 323 fork-lift truck 56 Cousteau, Jacques 379 dish, communications 252 electrons 150, 182, 183, 193, Forlanini, Enrico 379 CPU (central processing unit) disk drive, computer 332, 335 196, 230, 231, 256-7, 258, four-stroke engine 156-7 340, 344 dishwasher 136 259, 266-73, 296 Fox-Talbot, William 383 cranes 56, 57, 58 distance counter 38, 46 electrostatic precipitator 262 Francis turbine 33 cranks 48-53, 376 diver, aqualung 131, 379 electrowetting 220, 221 Franklin, Benjamin 386 Cristofori, Bartolomeo 375 domain, magnetic 276 endoscope 187, 382 frequency modulation (FM) 242 cruise control 309 door, automatic 305 energy: friction 82, 89 frequency, radio wave 242, 243, crystals, piezoelectricity 264-5 drag 107 heat 142 Ctesibius 375, 379 Drake, Edwin 377 nuclear 166-7, 172-4 244 current, electricity 259, 266-7 Drebbel, Cornelius 383 power stations 160 friction 28, 54, 62, 63, 65, 77, cutting machines 13, 67, 68 drill chuck 44 springs 79 cylinder lock 13, 374 drills 66, 377 engines: aeroplane 108 82-9, 107, 377 dentist’s 35 cams and cranks 49-51 friction-drive toy 72 D oil rig 87 carburettor 140-1 fuel injection 140 pneumatic 127 diesel 380 fulcrum, levers 18-23 Daguerre, Louis 383 drinking straw 130 gearbox 40-1 furnace 148-9 Daimler, Gottlieb 380 driving gears 38 hybrid 158, 159 fuse 286 Darby, Abraham 380 driving mirror 186 internal combustion 156-7, fusion, nuclear 169, 170 data, digital machines 331 drone 118 376 data compression 207, 332, drum brakes 86 jet 156, 162-3, 380 G drums 226, 384 petrol 156-7, 380 389 rocket 156, 164-5 Gabor, Denis 383 de Forest, Lee 385, 389 E starter motor 73 Galileo 375, 380, 383 density 94, 97, 99 epicyclic gears 39, 308, 375 Galvani, Luigi 386 dental X-ray 296-7 e-mail 350-1 Ericsson, John 378 gamma rays 170, 304 dentist’s drill 35 e-reader 221 escalator 60-1, 376 Garnerin, André 377 derailleur gears 38 ear, hearing 223 escapement 42 gas boiler 146 Descartes, René 386 earphone 233, 362, 364 Euclid 382 gas laser 196 Earth observation satellite 249 gases: heating 143 earthquake, seismograph pressure 120 292-3, 387 propellants 138 echo sounding 298-9 gear pump 124 [397]

INDEX gearbox 35, 40-1, 84-5, 308-9 I L lubrication, car 88 gears 36-47, 135, 308, 375 Lumière, Auguste and Louis generator 173, 252, 284-5 icons, computer 318 lamps 183 Giffard, Henri 378 idler wheel 41 lander 253 383 Gilbert, William 386 ignition system, car 288-9 Langevin, Paul 388 glasses, 3D 209 images, 179, 182-3, 323, 324, laser 196-8, 383 M glider 106, 107, 110, 378 Goddard, Robert 381 382 Blu-ray player 200-1 Macmillan, Kirkpatrick 377 Golitsyn, Prince Boris 387 digital 204, 205, 206, 207 printing 215, 282, 360, 361 maglev train 283 governor, automatic printing 210-11 telecommunications 237, 351 magnetic lens, electron quality of 207 lawn mower 39 transmission 306 inclined plane 10-17, 62, 63, lawn sprinkler 47 microscope 193 GPS (Global Positioning 374 leaf spring 80, 81, 377 magnetism 274-89, 302-3, induction, magnetic 46, 276 Lee, Edmund 387 System) 355, 389 induction motor 283 Leibniz, Gottfried 388 386 gravity: and flight 107 industrial robot 366 lenses 188-9, 382 loudspeaker 232 inertia 70-3, 77, 293 binoculars 192 magnetic compass 387 gyroscope 76, 77 inertial guidance 293 camera 188-9, 205 magnetic field coil 175 parachute 83 infra-red 144, 196, 243 endoscope 187 magnetic induction 46, 276 gravure printing 210 burglar alarm 305 magnifying glass 189 storing bits 335 Greek mill, waterwheel 32 remote control unit 272-3 microscope 193, 383 magnetometer 252 grinding 87 ink, electronic 220, 221 projector 208 magnifying glasses 189 grip, friction 82 ink-jet printer 360 telescope 190, 382 Maiman, Theo 383 guitar, electric 229 inks, printing 215, 216, 360 Leonardo da Vinci 377 Marconi, Guglielmo 385 gun cartridge 147 input unit 332, 344 letterpress, printing 210, 384 mass, inertia 70, 293 gunpowder 381 insulation, 145 lever escapement 42 master cylinder, hydraulics Gutenberg, Johan 384 integrated circuits see lever lock, 13 128, 129 gyrocompass 77, 377 microchips levers 18-29, 31, 57, 374 Maxwell, James Clerk 383 gyroscope 76-7, 99, 293, 377 internal combustion engine lift 54 mechanical mole 67 156-7, 376 flight 106, 107, 114 media player 341 H Internet 206, 238, 248, 348, hydrofoil 119 medium wave, radio 244, 245 349, 350-1, 389 lifts 60-1, 129, 376 memory card 203, 207, 208, hairdryer 150 ionizer 262, 263 light 180-209, 382 334 hairspring 42, 134, 377 ionizing smoke detector 295 speed of 243 memory, digital machines hammer 23 ionosphere 245 light aircraft 110 323, 324, 331-7, 344 hand drill 66 ions 262, 263, 264, 268 light bulb 182, 183 Mesmer, Franz Anton 386 hang glider 110 iris, camera 205 light-emitting diode (LED) metal detector 302 hard disk 207, 208, 277, 332, iron 148-9, 276, 380 221, 273 meter, water 135 computer mouse 318 microchip 265, 272, 293, 294, 335, 344, 368, 370 J lamp 183 295, 340, 341, 342-3, 345, Harington, Sir John 380 laser printer 361 354, 389 Harrison, James 380 jack-hammer 127 organic light-emitting diode micrometer 64, 377 headlamp mirror 186 jacks 57, 64, 365 (OLED) 240, 247, 320 microphone 228, 231, 237, hearing 223 James, Francis 375 light rays 180-1, 186, 192 240, 242, 322, 324, 363 heat 142-73, 323, 380 Jansky, Karl 385 digital images 322 microprocessor 241, 309, 343, heavier-than-air flight 106 Janssen, Zacharias 383 heat 144 389 helicopter 106, 114-18, 379 jet engine 108, 156, 162-3, 380 lenses 188-9 microscope, 186, 191, 383 helium: airship 104 jet pack 137 lighting 182-3, 382 microwaves, 144, 239, 305 jets and sprays 136-7, 379 polarized, 383 mincer 67 nuclear fusion 167, 173 jib sails, windmill 34 refraction 188 mirror 186, 208, 382 Henry, Joseph 386, 387 joystick: aircraft 118 light waves 243 mixers: electric 46 Hero 376, 380 telecommunications 237 synthesizer 229 Hertz, Heinrich 385 games controller 326 lightning conductor 262-3 mobile phone 238 Hippocrates 375 Judson, Whitcomb 374 linear induction motor 283 smartphone 240-1, 320, 321, hoists 56, 59 Lippershey, Hans 382 334, 350, 363, 385 hologram 197, 198-9, 383 K liquid crystal display (LCD) modem 350 Hooke, Robert 377 118, 194, 195, 208, 209, modulator, Hoover, William 379 Kelly William 380 246-7, 320 telecommunications 242 horn, electric 279 kettle, electric 150 liquid-fuel rocket 165 moles, mechanical 67 hot-air balloon 94, 105, 378 kettledrum 226 liquids: capillary action 141 monitor, computer 158, 247, hovercraft 126, 379 key 12-13 heating 143 344, 361 Hubble space telescope 251 keyboard 375 hydraulic machines 128-9 Montgolfier brothers 378 Huygens, Christiaan 382 jets and sprays 136 Morse, Samuel 384 hydraulic platform 29 computer 317, 318, 320, 344, pressure 120 Morse code 384 hydraulics 29, 86, 108, 127, 388 see also water MOSFETs transistor 343 electric 228, 316, 360 lithium 169, 174, 175 motors: electric 280-1, 387 128-9, 379 keypad 316 lithography 211 linear induction 283 hydroelectric turbine 33 Kilby Jack 389 load line 99 stepper 282-3 hydrofoil 119, 379 kilobyte 332 locks 12-13, 316, 374 see also engines hydrogen, nuclear fusion 169 kinetic energy 89, 158, 159 logic gate 340, 341, 342, 388 mouse 318-19 hydrogen bomb 170, 381 kite 106, 110, 378, 386 long-life battery 268 movie camera, 206, 383 hydroplane 97 Korolev, Sergei 381 loudspeaker 232, 234, 240 movie projector, 207 hypertext markup language Moy Thomas 379 MP3 324, 389 (HTML) 353 [398]