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In assocwEyewitness

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Eyewitness

INVENTION

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19th-centurybrace and bit

Early Italianmicroscope

Cross-barwheel

Radio valve

Candlesticktelephone

19th-centuryfountain pens

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Eyewitness

INVENTIONWritten by

LIONEL BENDER

Lenses fromdaguerreotypecamera Ancient Egyptian

weights

Roman beam balance

Smallswooden plough

1940s ballpoint pen

Napiers bones,17th-century

calculating device

DK Publishing, Inc.

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LONDON, NEW YORK,MUNICH, MELBOURNE, and DELHI

Project editorPhil Wilkinson

Design Matthewson BullSenior editorHelen Parker

Senior art editors Jacquie Gulliver, Julia Harris

ProductionLouise Barratt

Picture research Kathy Lockley

Special photographyDave King

Additional text Peter Lafferty

Editorial consultants Staff of the Science Museum, London

Revised Edition

Managing editors Linda Esposito, Andrew Macintyre

Managing art editor Jane Thomas

Category publisher Linda Martin

Art director Simon Webb

Editor and reference compiler Clare HibbertArt editor Joanna Pocock

Consultant Roger Bridgman

Production Jenny Jacoby

Picture research Celia Dearing

DTP designer Siu Yin Ho

U.S. editors Elizabeth Hester, John Searcy

Publishing directorBeth Sutinis

Art director Dirk Kaufman

U.S. DTP designer Milos Orlovic

U.S. production Chris Avgherinos, Ivor Parker

This Eyewitness Guide has been conceived by

Dorling Kindersley Limited and Editions Gallimard

This edition first published in the United States in 2005

by DK Publishing

375 Hudson Street, New York, NY 10014

08 09 10 9 8 7 6 5

Copyright 1991, 2005, Dorling Kindersley Limited

All rights reserved. No part of this publication may be

reproduced, stored in a retrieval system, or transmitted

in any form or by any means, electronic, mechanical,

photocopying, recording, or otherwise, without the

prior written permission of the copyright owner.

Published in Great Britain by Dorling Kindersley Limited

A catalog record for this book is

available from the Library of Congress.

ISBN-13: 978-0-7566-1075-3 (PLC)

ISBN-13: 978-0-7566-1076-0 (ALB)

Color reproduction byColourscan, Singapore

Printed in China by Toppan Co.

(Shenzhen) Ltd.

Discover more at

Ivoryportablesundial

Chinesemeasuring

calipers

19th-centurysyringes

Ashantigold

weights

Earlytelephonehandset

Stone-headed axfrom Australia

Medievtally st

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Contents

6What is an invention?

8The story of an invention10

Tools12

The wheel14

Metalworking16

Weights and measures18Pen and ink

20Lighting

22Timekeeping

24Harnessing power

26Printing28

Optical inventions30

Calculating32

The steam engine34

Navigation and surveying36

Spinning and weaving38

Batteries40

Photography

42Medical inventions

44The telephone

46Recording

48

The internal combustion engine50Cinema

52Radio

54Inventions in the home

56The cathode ray tube

58Flight60

Plastics62

The silicon chip64

Did you know?66

Timeline of inventions68Find out more

70Glossary

72Index

Chinesemariners

compass

18th-centuryEnglish

compass

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GLASS

Nobody knowswhen the process of

glass-making (heating soda and sandtogether) was first discovered, although

the Egyptians were making glazed

beads in c. 2500b.c

. In the1st century b.c., the Syriansprobably introduced glass-

blowing, producingobjects of many

differentshapes.

FOOD FOR

THOUGHT

The first tincans had to beopened by hammerand chisel. In 1855, aBritish inventor, Yeates,developed this claw type ofcan opener. The blade cutaround the rim of the tin using aseesaw levering action of the handle.

Openers were given away with cornedbeef, hence the bulls-head design.

6

What is an invention?

An inventionis something that is devised by human effort and that didnot exist before. A discovery on the other hand, is something that existed but wasnot yet known. Inventions rarely appear out of the blue. They usually result fromthe bringing together of existing technologies in a new way in response to

some specific human need, or as a result of the inventors desire to do somethingmore quickly or efficiently, or even by accident. An invention can be the result ofan individuals work, but is just as likely to come from the work of a team. Similarinventions have even appeared independently of each other at the same time in

different parts of the world.

Handle

Bullshead

Blade

IN THE CAN

The technique of heating food to a hightemperature to kill harmful bacteria, thensealing it in airtight containers so that it can bestored for long periods, was first perfected byNicholas Appert in France in 1810. Appert used glass

jars sealed with cork, but in 1811 two Englishmen,Donkin and Hall, introduced the use of tin vacuumcans and set up the first food-canning factory.

Lid

Glass beads

CUTTING EDGE

Scissors were invenmore than 3,000 yeago in various placeabout the same tim

Early scissors resemtongs with a springwhich pushed theblades apart. Moderscissors use t heprinciple of the pivoand the lever to incrthe cutting power.

Shha

P

Lb

Arms allow user toadjust depth anddirection of cut

Glassbottles

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PENCIL IN THE DETAILS

Pencil lead was inventedindependently in France and

Austria in the 1790s. Pencilmakers soon discovered that by varying the relative

amounts of the two main components of the lead(graphite and clay), they could make leads of differenthardnesses.

LIGHTING-UP TIME left

The electric light bulb evolved fromearly experiments that showed thatan electric current flowing through awire creates heat due to resistance inthe wire. If the current is strongenough, the wire glows white-hot.

There were several independentinventors, including Thomas Edisonand Joseph Swan. Carbon-filamentlamps were mass-produced from theearly 1880s.

7

FIRELIGHTERS

Modern matches wereinvented by British

chemist John Walker in1827. He used splinters of

wood tipped with amixture of chemicals.These chemicals were

ignited by heat generatedfrom the friction of rubbing

the tip on sandpaper.Matches like this were laterknown as lucifers, from the

Latin for light bearer.

Lockmechanism

LOCKED UP

In the earliest known locks, the keywas used to raise pins or tumblers sothat a bolt could be moved. Today,the two most common types arecalled the mortise and the Yale.

Iron keyZIP-UP

The zipper was invented by USengineer Whitcomb Judson in1893. It consisted of rows ofhooks and eyes that werelocked together by pulling aslide. The modern version,with interlocking metal teethand slide, was developed byGideon Sundback and patentedin 1914.

Sandpaper

MASHED UP belo

Paper was first produced in China aroun50 b.c. The earliest examples were made fro

a mixture of cloth, wood, and straw (p. 19

Paper scroll

Bulb fromwhich air isextracted

Circuitconnector

GETTING THE

MEASURE OF IT above

The tape measure evolved from the measuring chainsand rods first used by the Egyptians and then the

Greeks and Romans. This exampleincorporates a notebook and

dates from 1846.

Linen tape

Winder to take uptape into container

IN THE SOIL

The plow developed in about5000 b.c. from simple hoes and digging

sticks that had been used by farmers forthousands of years. By changing the

shape and size of its various parts,it was gradually found that the

soil could be cut,loosened, and turned

in one operation.

Colter to cutloose the soil

Moldboard to liftand turn soil

Harness link toattach team of horsor oxen

Share to cut loosetop layer of soil

Metal filament

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8

The story of an inventionThe creation of an inventionoften involves many people,and inventions can take a long time to reach their final form.Sometimes an invention can takecenturies to evolve, as the effects of

different developments and newtechnologies are absorbed. After tracingthe history of drilling tools, it isapparent that the invention of thefamiliar hand drill and bit evolvedfrom refinements to the simple awland the bow drill, over hundreds of

years. Among the earliest tools for boring holeswere those used by the ancient Egyptians.Around 230 b.c. the Greek scientistArchimedes explored the use of levers and

gears to transmit and increase forces.But it was not until the Middle Agesthat the brace was developedfor extra leverage; thewheelbrace drill, which usesgears, evolved evenmore recently.

The position in whicha bow drill was used

Woodenbow Cord

Woodenhandle

Mouthpiece

Bone bow

Leatherstrip

Wooden hearth

Metalpoint

HOLE IN ONE

The ancientEgyptians used thisearly awl to makestarter holes for abow drill bit and tomark the points onplanks where

wooden pegs wereto be fitted.

HOT SPOTS

We do not know whether the bow drillwas first developed for woodworking orfire making. The example above is a firedrill. With a bone as the bow, a leatherstrip was used to rapidly rotate a woodendrill on a wooden hearth. Friction betweenthe drill and the hearth generated enoughheat to ignite some dry straw. It also madea hole in the wood.

BORING AWAY

Metal or flint bitswere fitted to thedrill shaft. A heavypebble could beused to push downon the shaft toapply morepressure to the bit.

GET THE

POINT

A combinationof the awl andthe simple bowdrill producedthis Egyptiandrill with a metalbit. Variousdifferent bitscould be used tomake wider ornarrower holes.

Metal bit

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9

AUGER

Corkscrew-like bits, oraugers, used

with a brace,have sidegrooves thatremove waste

wood from the

hole as the bitbites in.Screwdriverbits can beused with abrace, whichprovides moreturning forcethan ispossible withan ordinaryscrewdriver.

Screwdriverbit Auger Chuck

Mechanism tosecure drill head

WHEELBRACE

With gears, the brace drill was adaptedfor working in more confined spaces

and for easy control. Gears were addedto transmit the turning force at the

handle. With about 80 teeth on themain gearwheel and 20 on the

pinions, the bit is rotated 4 times foreach turn of the main wheel.

ChuckSelecti

of b

Pinio

Maiwhe

Grip

BRACE AND BIT

Bow drills

could not transmitenough turning forceto drill a wide diameterhole or to drill intotough materials. Usinga knowledge of levers,the brace was developed as a means ofincreasing the turning force. Thecranked handle provided leverage.The wider the sweep, the greater theleverage you could obtain.

SCREWED UP

The screw pump is used to raisewater. Archimedes explained it using

his understanding of the inclinedplane it is essentially a

rolled-up inclined plane.The principle of the

screw was not usedin drill bits untilmuch later.

Mainhand

Pinion

WincWiderthreadallowswasteto beremoved

Screwthread

FULL CIRCLE

The gimlet has athreaded tip. It canbe worked deeper

and can make wider holesthan a bradawl, with littleeffort. It is used to makestarter holes for screws.The handle is rotated,clockwise to work the toolin, counterclock-

wise to remove it.

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10

Tools DUAL-PURPOSE IMPLEMENT

The adze was a variation on the ax that appeared in the8th millenium b.c. Its blade was set almost at a right angle to thandle. This North Papuan tool could be used either as an ax(as here) or an adze, by changing the position of the blade.

Stone blade

Split woodenhandle

About 3.75million years agoour distant ancestors evolved anupright stance and began tolive on open grassland. Withtheir hands free for new uses,they scavenged abandonedcarcasses and gathered plant food. Gradually, earlypeople developed the use of tools. They used pebbles andstones to cut meat and to smash open bones for marrow.Later they chipped away at the edges of their stones sothat they would cut better. Nearly two million years ago,flint was being shaped into axes and arrow-heads, andbones were used as clubs and hammers. About 1.4 millionyears ago, humankind discovered fire. Now able to cookfood, our recent ancestors created a varied toolbox forhunting wild animals. When theystarted to farm, a different setof tools was needed.

STICKY END

This ax fromAustralia representsthe next stage ofdevelopment from t hehand ax. A stone was setin gum in the bend of aflexible strip of wood, andthe two halves of the pieceof wood were boundtogether. The ax was

probably used tokill wild animals.

GETTING STONED

This flint handax, found inKent, England, was first

roughly shaped with a stonehammer (above), then refined

with a bone one, It is perhaps20,000 years old. It dates from a

period known as the Old StoneAge, or Paleolithic period, whenflint was the main material used to

make tools.

NEXT BEST THING

Where flint was not available, softerstones were used for tools, as with

this rough-stone axhead.Not all stones could

be made as sharpas flint.

HOT TIP

Bow drills were first used torub one stick against anotherto make fire. The user movedthe bow with one hand andheld the shaft steady withthe other.

AX TO GRIND

To make this axhead, alump of stone was probably rubbed

against rocks and ground with pebblesuntil it was smooth and polished.

WELL-BRONZED

The use of bronze for tools and weaponsbegan in Asia about 8,000 years ago;

in Europe the Bronze Age lastedfrom about 2000 to 500 b.c.

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11

SHARP AS A KNIFE

The ancient Egyptianssharpened theirbronze tools, and .probably their swordsand daggers too, byscraping the cuttingedges on a smoothlump of sandstone.

JAGGED EDGE rightWoodworking as a craftbegan in Egypt around3000 b.c.Egyptian carpenters madefine objects to be buried in the tombsof the pharaohs. This cast from anearly flint knife, chipped to form aseries of teeth, represents one ofthe earliest examples of a saw. Serrated (notched) edge

MIND YOUR TOES

An adze could be used to hack atwood by holding it up in front of

your head then swinging it downhard between your legs.

Stonetip

Sharpeningstone

Bronze chiselsStone chisel

Stone weight

CHISELING AWAY below leftIn the Stone Age, stone tools, such as thisearly Danish chisel, or gouge (left), wereground and polished using other rock

materials. In ancient Egypt, bronzechisels (center) and chisel blades(right) fitted to wooden handles

were used to cut mortiseand tenon (interlocking)joints when making woodfurniture.

Woodencrosspiece

A CUT ABOVE THE REST

The ancient Egyptians,probably the most successful of theearly civilizations, used stone tools atfirst. Later they made tools andweapons in ivory, quartz, copper,bronze, and, around 1000 b.c., iron.They also developed wooden rulersand squares.

Bow of twine

Hole drilledby flint

ALL STRUNG UP

This recent pump drill fromNew Guinea was fitted with acast-iron bit. It was used to drillholes in wood. The bowstring,twisted around and secured tothe shaft, makes the shaft turn

as the stick is pumpeddownward.

BLOCKHEADS

To drill holes in stoneconstruction blocks, likethis practice piece, someearly peoples used flintdrill heads. These wereprobably attached to theends of forked sticks whichthe masons rotated rapidlyby rubbing thembetween their hands.

Flint drilling tool

Cord to

secureblade

HICK, HACK, HOCK

This adze from Fijihas a handle with abackward-pointingblade providing agood cutting edge.The blade is thick incross section, so thetool was probablyused for heavy-dutywork, perhapshollowing out treetrunks to make boats

Stone blade

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12

The wheel

The wheelis probably the most important mechanical invention of alltime. Wheels are found in most machines, in clocks, windmills, andsteam engines, as well as in vehicles such as the automobile and thebicycle. The wheel first appeared in Mesopotamia, part of modern Iraq,

over 5,000 years ago. It was used by potters to help work their clay,and at around the same time wheels were fitted to carts,transforming transportation and making it possible tomove heavy materials and bulky objects with relativeease. These early wheels were solid, cut from sections ofwooden planks which were fastened together. Spokedwheels appeared later, beginning around 2000 b.c.They were lighter and were used for chariots.Bearings, which enabled the wheel to turn moreeasily, appeared around 100 b.c.

Tripartite wheel

STONE-AGE BUILDERS left

Before the wheel, rollers made fromtree trunks were probably used to push

objects such as huge building stones intoplace. The tree trunks had the same effectas wheels, but a lot of effort was needed toput the rollers in place and keep the load balanced.

Solid woodensurface

Peg to holdwheel in

place

AxleAxle

Woodencross-piece

PLANK WHEEL

Tripartite or three-part wheels were madeof planks fastened together by wooden ormetal cross-pieces. They are one of theearliest types of wheel and are still used insome countries because they are suitablefor bad roads.

SCARCE BUT SOLID

Some early wheels were solid disks ofwood cut from tree trunks. These were notcommon, since the wheel originated inplaces where trees were scarce. Solid

wooden chariot wheels have been foundin Denmark.

Axle

ROLLING STONE

In some places, where woowas scarce, stone was usedfor wheels instead. It washeavy, but long-lasting. Thstone wheel originated inChina and Turkey.

Protective sh

for driver

Fixed woodenaxle

POTTERS WHEEL

By 300 b.c. the Greeks andEgyptians had invented thekick wheel. The disks heavy

weight meant that itturned at nearconstant

speed.

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13

Cut stoneconstruction

Axle

EARLY SEMISOLID WHEEL

Wheels could be made lighter bycutting out sections of wood. Wheelsof this type, called Dystrop wheels,

were made around 2000 b.c.

Axle

Holes makewheel lighter

Wheel

Wheel

Early Middle-Eastern cart

CROSSBAR WHEEL

If large sections of a wheel were cut away,the wheel could be strengthened withstruts or crossbars. From here it was a smallstep to the spoked wheel.

Spokes tstrengthwheel

Rollerbearings

ROLLERS

Around 100 b.c.Danish wagon-makers

probably tried puttingwooden rollers around theaxle in an attempt to make

the wheel turn moresmoothly.

MOVING AXLE

The moving axlewas fixed rigidlyto the wheel andturned with it.

FIXED IN PLACE

The fixed axle was rigid.It was attached to thechassis of the vehicle.The wheel turnedaround the axle.

Rotating axleChassis

HARVEST HOME

Wheels like this, with metal rims tolessen wear, were made as early as2000 b.c. They were used throughoutthe Middle Ages.

Rollerbearings

Fixed axle

Chassis

CROSSBAR

The horsewas strappedto the crossbar,

which was boundto the chassis withleather thongs.

Peg toholdwheel in

place

Wooden chassisbeam

WHEELS

AT WAR

The wheelmade possiblethe chariot,

which originatedin Mesopotamiaaround 2000 b.c.

Leatherthongs

LEATHER BEARING

Around 100 b.c., the Celts of Franceand Germany made carts with simpleaxle bearings. These consisted ofleather sleeves that fitted betweenthe axle and the wheel hub. Theyreduced friction, allowing the wheel

to turn easily.

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14

Metalworking

Roman ironnail, abouta.d. 88

Gold and silveroccur naturally in their metallic state. From earlytimes, people found lumps of these metals and used them for simpleornaments. But the first useful metal to be worked was copper, whichhad to be extracted from rocks, or ores, by heating in a fierce fire. The

next step was to make bronze. This is an alloy, made bymixing two metals together. Bronze, an alloy ofcopper and tin, was strong and did not rust or decay.It was easy to work by melting and pouring into ashaped mold, a process called casting. Because bronzewas strong as well as easy to work, everything fromswords to jewelry was made of the metal. Iron was firstused around 2000 b.c.Iron ores were burned withcharcoal, producing an impureform of the metal. Iron wasplentiful, but difficult to

melt; at first, it had tobe worked byhammeringrather thancasting.

CASTING FI

ST

When cold, the mwas broken o

and the obremoved. S

bronze is far hathan copper

can be hammto give it a s

cutting eBecause of bronze bec

the first metbe widely u

Iron ore

Bloom of iron

Partiallyhammered

bloom

CASTING FIRST STAGE

The first stage in producing bronze was to heatcopper and tin ores in a large bowl or a

simple furnace.Bronze is easier tocast into a variety

of shapes thancopper.

CASTING SECOND STAGE

The molten bronze was poured into a moldand allowed to cool and solidify. This processis called casting. Knowledge of bronze castinghad reached Europe by about 3500 b.c. andChina several centuries later.

BLOOM OF IRON

Early furnaces were not hot enough to meliron and so the metal was produced as aspongy lump, called a bloom. The bloom whammered into shape while white hot.

IRON SWORD-MAKING

In the first century a.d., iron swords were made

by twisting and hammering togetherseveral strips or rods of iron. This

process was called patternwelding.

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15

Iron strands boundtogether for strength

BraceletHairpin

Point made of pieces ofiron hammered together

Finished sword

DECORATIVE SWORDS

Pattern welding produceda strong blade that couldbe sharpened to make afine, strong cutting edge.The twisted iron strips formingthe blade produced anornamental pattern along itslength.

BRONZE ORNAMENTS

Bronze bracelets wereoften decorated with finepatterns. Ornamentalhairpins sometimes hadlarge hollow headscovered with patterns.

IRON HAMMER rightIron has been used forhammers for centuries.This simple iron hammercomes from the Sudan anddates from about 1930.

Barbed point

SMALL HANDS? aboveBronze swords often had ornamentalhandles and finger guards. Thehandles were often very short andcould not be held comfortably byhands as large as ours.

GETTING THE POINT

Iron was often used for weapons,which could be quite elaborate. Thisspearhead had a wooden handle.

Quertype of h

made wroug

iro

AFRICAN IRON

Making iron usingsimple furnaces was

still in practice in parts ofAfrica in the 1930s. These items

made in the Sudan were produced in aclay furnace and hammered into shape.

Flat surface to take baseof horses foot

Loop toaccept strap

The horse hobble, made ofwrought iron, was an early

form of horseshoe. It wasstrapped in place over the hoof

WROUGHT OR CAST ?

Wrought iron is a pure form of iron made in a simple furnace as a pastylump, which has to be hammered into shape. It was not possible to makemolten iron, which could be cast, until after the introduction of theblast furnace inthe 1300s a.d.

PINS AND NEEDLES

Bronze could be workedinto delicate, smallobjects, such as pins andneedles. It was also usedfor large objectssuch asbells andstatues.

ROMAN NAI

These iron nawere removed fro

Roman sites London and Scotlan

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16

Weights and measures

The first systemsof weightsand measures were developed in ancientEgypt and Babylon. They were needed to

weigh crops, measure plots of farmland, andstandardize commercial transactions. Around3500 b.c. the Egyptians were using scales;they had standard weights and ameasurement of length called the cubit,equal to about 21 in (52 cm). The Code ofHammurabi, a document recording thelaws of the king of Babylon from 1792 to1750 b.c., refers to standard weights anddifferent units of weight and length. By Greek and Romantimes, scales, balances, and rulers were in everyday use.

Present-day systems of weights and measures, the imperial(foot, pound) and metric (meter, gram), were established inthe 1300s and 1790s, respectively.

EarlyEgyptianstoneweights

MetalEgyptianweights

HEAVY METAL

Early Egyptians usedrocks as standard weights,but around 2000 b.c., as

metal-working developed,weights cast in bronze andiron were used.

Hook objectbe we

WORTH THEIR WEIGHT IN GOLD

The Ashanti, Africans from a gold-miningregion of modern Ghana, rose topower in the 18th century.They made standardweights in the form ofgold ornaments.

FishScorpion

SwordPointer

Pan

OFF BALANCE

This Roman beam balance forweighing coins consists of abronze rod pivoted at thecenter. Objects to be weighedwere placed on a pan hungfrom one end of the beamand were balanced againstknown weights hung fromthe other end. A pointer atthe center of the beamshowed when the pansbalanced.

Hollow to takesmaller weights

WEIGHING HIM UP

This ancientEgyptian balanceis being used in aceremony calledWeighing theheart, whichwas supposedto take placeafter a personsdeath.

Scale in inchesand centimeters

WEIGHTY NEST EGGS

With simple balances, sets of standardweights are used. Large or small weights areput on or taken off until the balance ishorizontal. These are French 17th-centurynesting weights; one fits just inside the nextto make a neat stack.

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17

NO SHORT MEASURES

This Indian grain measure was used to dispensestandard quantities of loose items. A shopkeeper

would sell the grain by the measureful rather thanweigh different quantities each time.

Volume

markhere

GETTING IT RIGH

One of t he most important thinabout weights and measures is th

they should be standardized, so theach unit of measure is always

identical value. These men atesting weights and measur

to ensure they aaccura

FLEXIBLE FRIEND leftTape measures are used in situations where a ruler istoo rigid. Measuring people for clothes is one of themost familiar uses of the tape measure; longer tapes are

used for land measurement and other jobs.

FILLED TO THE BRIM below

Liquids must be placed in acontainer, such as this copper

jug used by a distiller, in orderto be measured. The volumemark is in the narrow part ofthe neck, so t he right measurecan instantly be seen.

A BIG STEP above rightThis British size-stick formeasuring peoples feetstarts with size 1 as a4.33 inch length and

increases in stages ofone-third of an inch.

GRIPPED TIGHT above rightWrenchlike sliding calipers, used to measure the

width of solid objects and building materials such asstone, metal, and wood, were invented at least2,000 years ago. Measurements are read off a scale ona fixed arm, as on this replica of a caliper from China.

ALL HOOKED UP

The steelyard wasinvented by theRomans around 200 b.c. Unlike a simplebalance it had one arm longer than theother. A sack of grain would be hungfrom the short arm, and a single

weight moved along the longarm until it balanced. Thisexample date from the17th century.

Movable weight

Scale

USING THE STEELYARD rightOn a steelyard, the weight is movedalong the long arm, and the distancefrom the pivot to the balance-point,read off the scale marked on the arm,gives the objects weight. It had anadvantage for traveling merchants inthat they did not need to carry a largerange of weights.

STICKING TO ONES PRINCIPLES

The first official standard yard wasestablished by King Edward I of Englandin 1305. It was an iron bar divided into3 feet of 12 inches each. This is a19th century tailors yardstick usedto measure lengths of cloth. It alsohas a centimeter scale.

Foot positionedhere

Adjustable jaw

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18

Pen and ink

Written recordsfirst became necessarywith t he development of agriculture in the FertileCrescent in the Middle East about 7,000 years ago. TheBabylonians and ancient Egyptians inscribed stones, bones,

and clay tablets with symbols and simple pictures. They usedthese records to establish land tenure and irrigation rights, to keeprecords of harvests, and write down tax assessments and accounts. Aswriting implements, they first used flints, then the whittled ends ofsticks. Around 2500 b.c. the Chinese and Egyptians developed inksmade from lampblack, obtained from the oil burned in lamps, mixedwith water and plant gums. They could make different coloredinks from earth pigments such as red ocher. Oil-based inkswere developed in the Middle Ages for use in printing(p. 2627), but writing inks and lead pencils are moderninventions. More recent developments, such as the

fountain pen and theballpoint, were designedto get the ink on thepaper without theneed to keeprefilling the pen.

LIGHT AS A FEATHER

A quill the hollow shaft ofeather was first used as

pen around a.d.500. Drand cleaned goose, sw

or turkey feathers wemost popular becauthe thick shaft held

ink and the pen weasy to handle. T

tip was shaved tpoint with a k

and split slighto ensure ththe ink flow

smoothly.

HEAVY READING

The first writing that we have evidence

of is on Mesopotamian clay tablets.Scribes used a wedge-shaped stylusto make marks in the clay while itwas wet. The clay dried and left apermanent record. Themarks that make up thissort of writing arecalled cuneiform,meaning wedge-shaped.

A PRESSING POINT

In the 1st milleniumb.c. the Egyptians

wrote with reeds andrushes, which they cut to

form a point. They used thereed pens to apply lampblack to

papyrus.

ON PAPYRUS

AncientEgyptian and

Assyrian scribes wroteon papyrus. This was

made from pith takenfrom the stem of the

papyrus plant. The pithwas removed, arranged inlayers, and hammered tomake a sheet. The scribe

(left) is recording a battle.The papyrus (right) is from

ancient Egypt.

STROKE OF GENIUS

The ancient Chinese wrote theircharacters in ink using brushes of

camels or rats hairs. Clusters ofhairs were glued and bound to theend of a stick. For fine work on silk

they used brushes made of just a fewhairs glued into the end of a hollowreed. All 10,090 or more Chinesecharacters are based on just eight

basic brushstrokes.

Chinesecharacters

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Fiber tipInk reservoirfor earlyballpoint pen

Free-moving ball

Lever for filling pen

SOFTLY DOES

Fiber or soft-tipped pens were invented in t1960s. A stick of absorbent material acts

the ink reservoir. The tip-stalk, embeddedthe reservoir, contains narrow chann

through which ink flows as soon as the ttouches the pap

ON THE BA

The ballpoint pwas developed

John H. Loud in the US in the 1880s. The modeversion was invented by Josef and Georg Bir in th1940s. At the tip of an ink-filled plastic tube is a tin

free-moving metal ball. Ink flows from the tubthrough a narrow gap to the ball, whi

transfers the ink to the pape

CLOGGING UP THE WORK

Fountain pens were invented in Europe around 180Rubber tubing, inside a metal stem, was used

hold the ink, which was a solution natural plant dyes such as indig

Unless the dyestuff was fineground, the ink would cl

the nib. In 1884, EdsoWaterman invented the fi

true fountain pe

HIS NIBS

Dip pens, like those used inschools until the 1960s, had a

wooden stem, metal nib holder, andchangeable nibs. Early pen nibs, likethese, were all steel. Modern versionsare often tipped with hardwearing

metals such as osmiumor platinum.

Sharpenedpoint

Range of nibs fordip pens

FIT FOR A KING

The scribes of theMiddle Ages usedquill pens to producetheir elaboratelydecorated manuscripts.This example records thecoronation of King Henryof Castile in the 15thcentury. It shows thedelicate strokes that werepossible with quitesimple equipment.

MISSED THE POINT

Quill pens were worn downby the constant scrapingagainst the rough paper orparchment and from time totime had to be resharpened.In the 17t h century, quill-sharpeners were invented.The worn end of the quill

was snipped off neatly.

PapermakingThe earliest fragments of paper that have beendiscovered come from China and date fromaround a.d. 150. Knowledge of papermaking

eventually spread to Europe via the Islamicworld. The basic process remained similar tothat used in China. Paper was made from woodpulp and rags, which were soaked in water andbeaten to a pulp.

TRAY BY TRAY rightA tray with wire grids waslowered into the pulp, thegrid removed, and surplus

water shaken off.

HANGING OUT TO DRY

The resulting sheet was takenoff the grid and put on a piece

of felt before finally beinghung up to dry.

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20

MOLDS

Candles have been made in molds since the15th century. They made candle-making eaand were widely used in early American hoand shops.

HOLLOWED OUT left

The most basic form of lamp is ahollowed-out stone. This one camefrom the Shetland Islands and wasused during the last century. Butsimilar examples have been found inthe caves at Lascaux, France, datingfrom about 15,000 years ago.

COVERED

OVER

rightThe Romansmade clay lamps

with a covered top to keep the oil clean.They sometimes had more than onespout and wick to give a stronger light.

HoleforwickWick

UP THE SPOUT

Saucerlikepottery lamps have

been made for t housandsof years. They burned olive

oil or seed oil. This one wasprobably made in Egypt about2,000 years ago.

Spoutfor wick

SHELL-SHAPED right

By putting oil in the bodyand laying a wick in theneck, a shell could be used asa lamp. This one was used inthe 19th century, but shell lamps

were made centuries before.

Wick

COSTLY CANDLES

The first candles were madeover 5,000 years ago. Wax ortallow was poured over ahanging wick and left to cool.Such candles weretoo expensive formost people.

Containerfor wax Wicks

CAVE LIGHT

When early people made fire for cooking andheating, they realized that it also gave off lightSo the cooking fire provided the first source ofartificial light. From this it was a simple step tomaking a brushwood torch, so that light could carried or placed high up in a dark cave.

LightingThe first artificial lightcame from fire, but thiswas dangerous and difficult to carry around. Then,some 20,000 years ago, people realized that they couldget light by burning oil, and the first lamps appeared.These were hollowed-out rocks full of animal fat. Lampswith wicks of vegetable fibers were first made in about1000 b.c. At first, they had a simple channel to hold the wick;later, the wick was held in a spout. Candles appeared about5,000 years ago. A candle is just a wick surrounded by waxor tallow. When the wick is lit, the flame meltssome of the wax or tallow, which burns togive off light. So a candle is really an oil lampin a more convenient form. Oil lamps andcandles were the chief source of artificial

light until gas lighting became commonin the 19th century; electric lighting tookover more recently.

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21

Candleholder

LidHandle

DRY AS TINDER

Before the introduction of matches,tinder boxes were used to light firesand lamps. A spark was madeby striking a flint (thestriker) against a piece ofmetal (the steel). Somedry material (thetinder) in the boxwould catch fire.

LIGHTS OUT

Cone-shaped snufferswere often used to putout candles. There wasno smell and little riskof being burned.

Tinder

Steel

Striker

Tinder box

Cover toput out fire

TRIMMING THE WICK

With the appearance of moresophisticated oil lamps,elaborate tools were madeto cut the wicks. This wick

trimmer clips the wickand flicks the debris

into a container.

CANDLE POWER above

A single candle producesonly a little light one

candle power.

PROTECTOR

Lanterns wereused to shiel

the flamefrom thwind a

to reduce trisk of fire.Handle

to raisecandle

ON THE STREETS above

This engraving shows the firstcandle street lamp being lit inParis in 1667. The lamplighterhad to climb a stepladder toreach the lantern.

TWISTER left

This candlestick has aspiral mechanism. The

user twists it as thecandle burns down, tokeep the flame at the

same level.

SWEETNESS

AND LIGHT

Another way tomake a candle wasto use waxcollected from abeehive. This couldbe rolled into acylinder shape.

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22

TimekeepingKeeping track of timewas important to peopleas soon as they began to cultivate the land. But itwas the astronomers of ancient Egypt, some3,000 years ago, who used the regular movement of

the sun through the sky to tell time more accurately.The Egyptian shadow clock was a sundial, indicatingtime by the position of a shadow falling acrossmarkers. Other early devices for telling timedepended on the regular burning of a candle,or the flow of water through a small hole. Thefirst mechanical clocks used the regular rockingof a metal rod, called a foliot, to regulate themovement of a hand around a dial. Laterclocks use pendulums, which swing backand forth. An escapement ensures that this

regular movement is transmitted to the gears,which drive the hands.

BOOK OF HOURS

Medieval books ofhours, prayer bookswith pictures ofpeasant life in eachmonth, show howimportant the time of

year was to peopleworking on the land.This illustration forthe month of Marchis from Trs RichesHeures of Jean, duc

de Berry.

PLUMB LINE

The ancient Egyptian merkhet was usedto observe the movement of certainstars across the sky, allowing the hoursof the night to be calculated. This onebelonged to anastronomer-

priest ofabout600 b.c.named Bes.

Folding gnomon

Holes totake pin

COLUMN

DIAL

This smallivory sundialhas twognomons(pointers),one forsummer, onefor winter.

HANDY SUNDIAL right

This German folding sundial hasa string gnomon, which can beadjusted for different latitudes.The small dials show Italian andBabylonian hours. The dial alsoindicates the length of the dayand the position of the sun inthe zodiac.

TIBETAN TIMESTICK

The Tibetan timestick relied on theshadow cast by a pin through anupright rod. The pin would be placed indifferent positions according to thetime of the year.

String gnomon

Cover

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23

BALANCE-SPRING WATCH

Christian Huygens introducedthe balance spring in 1675. Itallowed much more accuratewatch movements to bemade. ThomasTompion, the makerof this watch,introduced thebalance spring to

England, giving thatcountry a leadingposition inwatchmaking.

BRACKET CLOCK belowThis type of clock wasmade in the 17th century.This example was madeby the famous Englishclockmaker ThomasTompion. It has dialsto regulate the

mechanism and toselect striking orsilent operation.

LANTERN CLOCK

This Japanese lanternclock was regulated bymoving small weightsalong a balance bar.The clock has only onehand indicating thehour. Minute handswere uncommonbefore the 1650s,when Dutch scientistChristian Huygensmade a more accurate

clock regulated by aswinging pendulum.

VERGE WATCH

Until the 16th century, clocks w

powered by falling weights, andcould not be moved around. Thuse of a coiled spring to drive thhands meant that portable clockand watches could be made, buthey were not veryaccurate. Thisexampleis fromthe 17thcentury.

CHRISTIAAN HUYGENS

This Dutch scientist made thefirst practical pendulum clock inthe mid-17th century.

Adjustableweights

WATER CLOCK

Su Sungs water clock,built in 1088, was housedin a tower 35 ft (10 m)high. Its water wheelpaused after each bucketfilled, marking intervals oftime. Gears conveyed themotion to a globe.

SANDS OF TIME aboveThe sandglass was probably first used in theMiddle Ages, around a.d. 1300, though thisis a much later example. Sand flowedthrough a narrow hole between two glassbulbs. When all the sand was in the lowerbulb, a fixed amount of time had passed.

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24

Harnessing power

Since the dawn of history, people havelooked for sources of power to make work easierand more efficient. First they made human

muscle power more effective with the use ofmachines such as cranes and treadmills. Itwas soon realized that the muscle powerof animals such as horses, mules, andoxen was much greater than that ofhumans. Animals were trained to pull heavyloads and work on treadmills. Other usefulsources of power came from wind and water.The first sailing ships were made in Egypt about5,000 years ago. The Romans used water mills forgrinding corn during the 1st century b.c. Water

power remained important and is still widely usedtoday. Windmills spread westward across Europein the Middle Ages, when people began to look fora more efficient way ofgrinding grain.

MUSCLE POWER

Dogs are still used in arctic regions to pull sleds,though elsewhere in the world the horse has

been the most common workinganimal. Horses were also used to

turn machinery such asgrindstones and

pumps.

POST MILL

Many of the earwindmills were post

mills. The whole millcould turn around itscentral post in order t

face into the wind.Made of timber,

many post millswere quite frag

and could bloover in a sto

HAUL AWAY!

This 15th-century cranein Bruges, Belgium, was

worked by men walkingon a treadmill. It isshown lifting winekegs. Other simplemachines, such as thelever and pulley, werethe mainstay of earlyindustry. It is said thataround 250 b.c.the Greekscientist Archimedes couldmove a large ship single-handed by using a systemof pulleys. It is not knownexactly how he did this.

THE FIRST WATER WHEELS

From around 70 b.c. we have records of the Romansusing two types of water wheel to grind corn. In theundershot wheel, the water passes beneath the wheel; inthe overshot wheel, the water flows over the top. Thelatter can be more efficient, using the weight of the waterheld on the blades.

Tail pole

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TURNING THE MILL

To turn the mill into thewind, the miller pushedthe tail pole near thestairs. Later mills had asmall wind wheel, called afantail, with its own smallsails. This turned the millautomatically.

Rope tooperatesack hoist

Cross trees

Revolvingbody orbuck

SUPPORTING THE MILL

The legs of this post millare visible, but they weresometimes enclosed in asolid wall. This type ofstructure evolved into thetower mill, which had asolid tower with a small cap

that could be turned toface the wind.

Brakewheelwith gearteeth todrive

runnerstone

Sailcloth

Windshaft

Stock

SA

Simple sails wmade fr

canvas stretchover a frame.

improved typesail was inven

by Andrew Meiin the 1770s

consisted of hingslats that were k

in place bspring. When twind became t

strong, the slopened, allowthe wind to p

harmlesthrou

Whip

ADAPTABLE POWER

In the Middle Ages, watermills were used for tasks

from cleaning cloth toblowing bellows for blastfurnaces. Later, they were

used to drive factory

machinery.

STANDARD leftThe Halladay StandardWindmill, introduced in the mid

1800s, is the forerunner of windpumps still used in remote areas.

INSIDE A POST MILL rightInside the mill, the shaft from the sails

was attached to a large gear wheel,called the brake wheel. This meshes

with another gear, called the stone nut,which was connected to a vertical shaft

that turned the runner stone.

Stone casecontainingmill stones

Fixed post

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26

PrintingBefore printing began, each copy of every book

had to be written out by hand. This made books rare andexpensive. The first people to print books were the Chineseand Japanese in the sixth century. Characters and pictures

were engraved on wooden, clay, or ivory blocks. When a papersheet was pressed against the inked block, the characters wereprinted on the sheet by the raised areas of the engraving. Thisis known as letterpress printing. The greatest advance inprinting was the invention of movable type single letters onsmall individual blocks that could be set in lines and reused.

This innovation also began in China,in the 11th century. Movable typewas first used in Europe in the15th century. The most importantpioneer was German goldsmith

Johannes Gutenberg. Heinvented typecasting a method of makinglarge amounts of movable type cheaplyand quickly. After Gutenbergs workin the late 1430s, printingwith movable typespread quicklyacross Europe.

EARLY TYPE

Blocks with onecharacter were

first used inChina in about1040. These are

casts of earlyTurkish types.

PUNCHES

Gutenberg used a hardmetal punch, carved with aletter. This was hammeredinto a soft metal to make amold.

This early Japanese woodenprinting block has a completpassage of text carved into asingle block of wood.

FROM THE ORI

This early Chinese book printed with wooden blocks, e

of which bore a single chara

Letter stamped in metal

IN GOOD SHAPE

Each matrix bore t heimpression of a letteror symbol.

POURING HOT METALA ladle was used to pour

molten metal, a mixture of tin, lead,and antimony, into the mold to form apiece of type.

THE GUTENBERG BIBLE

In 1455 Gutenberg produced the firstlarge printed book, a Bible which isstill regarded as a masterpiece of theprinters art.

CLOSE SH

A type planeused to shave

backs of the mtype to ensureall the letters w

exactly the she

Screw tosecure blade

Spring to holdmold closed

TYPE MOLD

The matrix was placed in the bottom ofa mold like this. The mold was thenclosed, and the molten metal waspoured in through the top. The sides

were opened to release the type.

Metal blade

Mold inserted here

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HELD TIGHT

When the type wascomplete, it was placedin a metal frame called achase. The type waslocked in place withpieces of wood or metalto make the form. Theform was then placed inthe printing press, inked,and printed.

GUTENBERGS WORKSHOP

About 1438 Johannes Gutenberg inventeda method of making type of individualletters from molten metal. The printersseen here are setting type and using the

press in Gutenbergs workshop.Printed pages are hanging

up for the ink to dry.

Type forminga single page

Screw lockstype in place

Adjustable grip to setwidth of lines

Compositor setting typeby hand

REVERSED WORDS aboveEarly printers arranged type into

words on a small tray called acomposing stick. The letters have tobe arranged upside down and fromright to left the printed impressionis the mirror image of the type.

SPACING THE WORDS belowThe type on this modern composing stickshows how you could adjust the length ofthe line by inserting small pieces of metalbetween the words. These would notprint because they are lower than t heraised type.

Spacer

Piece oftype How the traditional

composing stick washeld in the hand

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28

Optical inventions

The science of opticsis based on the fact that light raysare bent, or refracted, when they pass from one medium toanother (for example, from air to glass). The way in whichcurved pieces of glass (or lenses) refract light was knownto the Chinese in the 10th century a.d. In Europe in the13th and 14th centuries, the properties of lenses beganto be used for improving vision, and eyeglasses appeared.For thousands of years, people used mirrors (made at firstof shiny metals) to see their faces. But it was not until

the 17th century that more powerful opticalinstruments, capable of magnifying very small items andbringing distant objects into clearer focus, began to bemade. Developments at this time included the telescope,which appeared at the beginning of the century, and themicroscope, invented around 1650.

IN THE DISTANCE

The telescope musthave been inventedmany times whenever someoneput two lensestogether like this andrealized distantobjects could be madeto look larger.

BLURRED VISION

Eyeglasses, pairs of lenses focorrecting sight defects, havbeen in use for over 700 yeaAt first they were used onlyreading, and like the onesbeing sold by this earlyoptician, were perched on thnose when needed. Eyeglasfor correcting near-sightednwere first made in the 1450

17th-centuryeyeglasses

17th-centuryglass was often

colored

GLASS EYES?

Convex (outward-curving) lenseswere known in 10th-centuryChina, but the use of lenses forreading glasses and to makeeyeglasses for the far-sightedprobably began in Europe.These 17th-century readingglasses use convex lenses.

Leather-coveredtube

Lens cap

STARGAZING

The celebratedItalian scientist and

astronomer Galileo Galileipioneered the use of refracting

telescopes to study the heavens.This is a replica of one of Galileos

earliest instruments. It has a convex lens atthe front and a concave (inward-curving)

lens at the viewing end.

COLO

THE

Early refracting telescsuch as this 18th-ceEnglish model, prod

images with blucolored edges, bec

their lenses bendifferent colors of

by different amoun1729, Chester Moor

had a main lens mby putting togethelenses made of diffkinds of glass. The

distortion of one lencounteracted by the o

Concave lens

Convex lens

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29

TWO FOR A

TENOR

Simple binoculars,like these 19th-centuryopera glasses decorated

with mother-of-pearl andenamel, consist of twotelescopes mounted side-by-side. Prism binoculars hadbeen invented by 1880. Theprism, a wedge of glass, foldedthe light rays, shortening thelength of t he tube needed and allowinggreater magnification in a smaller instrument.

18th-century

pocket telescope

Eyepiece

Focusadjuster

ON THE LEVEL

A quadrant and plumb line arefitted to this 17th-century

telescope. They help theastronomer work out

the altitude of anobject in the sky.

PEEPING TOM

Jealousy glasses were sometimesused by the 18th-century Englishgentry for keeping an eye on oneanother. A mirror in thetube reflects the light raysso that you could look toone side when it seemed

that you were lookingstraight ahead.

Geared focusing mechanism

ON

REFLECTION

The reflectingtelescope uses a mirror

lens. This avoids the problemof color distortion and the need

for long focal-length lenses, whichrequired long viewing tubes. This versionhas two mirrors and an eyepiece lens.

Lens cap

Lens capCOMPOUND INTEREST aboveThe compound microscope has not onebut two lenses. The main lensmagnifies the object, and theeyepiece lens enlarges themagnified image.

Objectivelens

ANTON VAN LEEUWENHOEK

(16321723) leftDutchman Leeuwenhoek taughthimself to grind lenses and madesimple microscopes with a tinylens in a metal frame. Obtainingmagnifications of up to 280 times,he was one of the first to studythe miniature natural world,and described very littleand odd animalcules indrops of pond water.

Eyepiece lens

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30

CalculatingPeople have alwayscounted and calculated, but calculating became veryimportant when the buying and selling of goods began. Apart from fingers,the first aids to counting and calculating were small pebbles, used to representthe numbers from one to ten. About 5,000 years ago, the Mesopotamians

made several straight furrows in the ground into which the pebbles wereplaced. Simple calculations could be done by moving the pebbles from onefurrow to another. Later, in China and Japan, the abacus was used in the same

way, with its rows of beads representing hundreds,tens, and units. The next advances did not comeuntil much later, with the invention of calculatingaids like logarithms, the slide rule, and basicmechanical calculators in the 17th century a.d.

Upper beads arefive times thevalue of lower

beads

USING AN ABACUS

Experienced users cancalculate at great speed witan abacus. As a result, thismethod of calculation has

remained popular in Chand Japan evin the age of thelectroniccalculator.

POCKET CALCULATOR

The ancient Romans used an abacus similar tothe Chinese. It had one bead on each rod in theupper part; these beads represented five times

the value of the lower beads. This is a replica ofa small Roman hand abacus made of brass.

THE ABACUS

In the Chinese abacus,there are five beads onthe lower part of a rod,each representing 1,and two beads on theupper part, eachrepresenting 5. Theuser moves the beadsto perform

calculations.

HARD BARGAIN

Making quick calculations becameimportant in the Middle Ages, whenmerchants began to trade all aroundEurope. The merchant in this Flemishpainting is adding up the weight of anumber of gold coins.

Notches

USING LOGARITHMS below

With logarithms and a slide ruleit is possible to do complicatedcalculations very quickly.

KEEPING ACCOUNTS

On tally sticks, the figures were cut intothe stick in the form of a series of notches.The stick was then split in two along itslength, through the notches, so eachperson involved in the deal had a record.

Parallel scales

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NAPIERS BONES

These calculating rods were invented by John Napier inthe early 17th century. They had numbers from 1 to 9 atone end. The numbers along the sides of the rods weremultiples of the end number. To find the multiples of anumber x, the rods representingxwere laid side by side;the answers were found by adding adjacent numbers.

Answers appear here

Blaise PascalNumbers dialed in here

PASCALS CALCULATOR

Pascal created his calculator o1642 to help his father, a taxofficial. The machine consisteof a number of toothed

wheels with numbers inconcentric rings. Numbers tobe added or subtracted weredialed in, and the answerappeared behind holes.

Pegs toturn rods

READY RECKONER

This device uses the principle ofNapiers bones, but the numbersare engraved on turning rollers,

which meant that the parts wereless likely to get lost.

Numbon turn

r

WHAT A GEM!

This arithmetical jewel,made of brass and ivory byWilliam Pratt in 1616, is an aidto addition and subtraction. A

stylus was used to move wheelsmarked with numbers. It was

probably owned by awealthy person.

Stylus

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The steam engineThe power developed by steamhas fascinated people for hundreds of years.During the first century a.d., Greek scientists realized that steam containedenergy that could possibly be used by people. But the ancient Greeks did notuse steam power to drive machinery. The first steam engines were designed at

the end of the 17th century by engineers such as the Marquis ofWorcester and Thomas Savery. Saverys engine was intended tobe used for pumping water out of mines. The first really practicalsteam engine was designed by Thomas Newcomen, whose first

engine appeared in 1712. Scottish instrument-maker James Watt improvedthe steam engine still further. His engines condensed steam outside themain cylinder, which conserved heat by dispensing with the need alternatelyto heat and cool the cylinder. The engines also used steam to force thepiston down to increase efficiency. The new engines soon became a majorsource of power for factories and mines. Later developments included themore compact, high-pressure

engine, which was used inlocomotivesand ships.

Parallel motion Cylin

GREEK STEAM POWERSome time during the 1st century a.d.,the Greek scientist Hero of Alexandriainvented the olipile a simple steamengine that used the principle of jetpropulsion. Water was boiled inside thesphere, and steam came out of bent jetsattached it. This made the ball turnaround. The device was not used forany practical purpose.

Valve chest

Eduction

pipe tocondenser

Air pump

Cistern containingcondenser and air

pump

PUMPING WATER

English engineerThomas Savery patented amachine for pumping waterfrom mines in 1698. Steamfrom a boiler passed into a pairof vessels. The steam was thencondensed back into water,creating a low pressure areaand sucking water from themine below. Using stop cocksand valves, steam pressure wasthen directed to push the

water up a vertical outlet pipe.Thomas Newcomen, anEnglish blacksmith, improvedon this engine in 1712.

Hero ofAlexandriassteam engine

Piston rod

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Governor

Newcomens engine was called a beam engine.The huge beam on top rocked back and forth,transferring power from a piston moving in acylinder to gears turning a wheel. Steamentered the cylinder as the pistonmoved up and was then condensed.Air pressure then forced the pistondown. James Watt improved theengine.

Beam

Richard Trevithick (1771-1833), a British mining engineer,developed a small steam engine using high-pressure steam,which he used to power the first steam locomotive in 1804.George Stephenson (1781-1848) built his first locomotive, the

Blcher, in 1814. This was followed by other locomotives,such as the Rocket, the first vehicle to travel faster than

a horse. It reached a speed of 29 mph (47 km/h).

WAITING FOR THE END belowPeople took their carriages on the train sothat t hey had transportation when theygot to the end of the line.

Flywheel

Crankshaft

AT SEA

The first steamship to cross thAtlantic was the Savannah. In1819, it sailed from NewYork to Liverpool, England

in 21 days. Like most earlysteamships, it had sails aswell as an engine. Somuch space was neededfor fuel that there waslittle room for passengerand cargo. The first shipto cross the Atlanticunder steam power alonwas the Sirius, whichsailed from London toNew York in 1838.

Connectingrod

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34

Navigation and surveyingThe more people traveledby boat, the moreimportant the skills of navigation became.Navigation probably originated on the Nile and

Euphrates rivers about 5,000 years ago when the Egyptians

and Babylonians established trading routes. The Egyptiansalso pioneered surveying, essential for creating large buildingssuch as the pyramids. Navigation and surveying are relatedbecause both deal with measuring angles andcalculating long distances. From around500 b.c., first the Greeks, then the Arabs andIndians, established astronomy, geometry, andtrigonometry as sciences and created suchinstruments as the astrolabe and compass.

Understanding the movementsof heavenly bodies and the

relationship between anglesand distances, medievalseafarers were able to create a

system of longitude and latitudefor finding their way at sea without

reference to landmarks. The Romanspioneered the widespread use of accuratesurveying instruments, and Renaissancearchitects added the theodolite, our mostimportant surveying tool.

Stonessuspended

from crossedsticks set at

right angles toone another

RIGHT

ANGLE aboveEarly surveyorsinstruments such as theEgyptian groma wereuseful only on flat terrainand for setting alimited range ofangles. With t hegroma, distantobjects were markedout against the

position of the stonesin a horizontal plane.

Brass markerSTRETCHING IT OUTRopes, chains, tapes, and rods have all been used formeasuring distances. In about 1620, EdmundGunter developed this type of metalchain for determining the area of plots ofland. The chain is 66 ft (20 m)long and is made of 100links. Markers areplaced at regularintervals.

IN THE RIGHT DIRECTION

Magnetic compasses were used in Europe babout a.d.1200, but the Chinese are though

have noticed about 1,500 years befothat a suspended piece of lodeston

(a magnetic ironmineral) pointsnorthsouth.

18th-centuryEnglishcompass

Chinesemariners

compass

Centraarm

OCTAN

In the 1730s, Englisseafarer John Hadle

invented the octant. Thversion is from abo

1750. It enable

navigators to measure thaltitude of the sun, moo

and stars so that thecould find their latitud

Chainlink

Handle

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35

SETTING BY THE SUN aboveMedieval surveyors and navigatorsused instruments like the astrolabe(bottom right), the cross-staff (topright), and a measuring compass (left).

The astrolabe was a 5th-centuryArab development of ancientGreek astronomical instrumentsused to tell the local time by theposition of the sun in the sky.

TURNING FULL CIRCLE

In 1676, Italian JoannesMacarius was so proudof this highly decoratedcircumferentor that hehad his name engraved onit. It enabled the user tocompare angles and figure outhow far away a distant object

was.

Sight

Mirror

Three sets of degrees andangles on a graduated(divided) scale

Scales oflength

Sight

BURNING BRIGHT

The Pharosin Alexandria

Egypt was thefirst lighthouse and

one of the seven

wonders of the ancienworld. Built in about300 b.c., it stood 350 f(110 m) tall. Its mirrorprojected light from agiant fire to ships farout at sea.

Telescopic sight

Ebony frame

Ivoryscale

SMALL SEXTANT aboveSextants like this one from1850 were used by army

personnel androadbuilders formaking military

maps and

surveying landfor roads orrailways.

STARRY-EYED

The octant was notgood for working

out longitude.In England in 1757, John Campbell

developed the sextant formeasuring both longitude

and latitude.

Surveyorusing a

backstaff

Scalemeasuringangles

HALFWAY HOU

The graphometer was a surveyoinstrument with a graduated half-circlewas first described by Frenchman Phill

Danfrie in 1597 and was a forerunnerthe circumferent

Sights

Graduated angle scale

Reading marker

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CLOTHMAKING IN THE MIDDLE AGES

In about a.d. 1300, an improved loomwas introduced to Europe from India.

was called the horizontal loom and haframework of string or wire to separatthe warp threads. The shuttl

was passed across thloom by hand.

36

Spinning and weavingEarly peopleused animal skins to help them keep warmbut about 10,000 years ago, people learned how to makecloth. Wool, cotton, flax, or hemp was first spun into athin thread, using a spindle. The thread was then woven

into a fabric. The earliest weaving machines probablyconsisted of little more than a pair of sticks that held aset of parallel threads, called the warp, while the cross-thread, called the weft, was inserted. Later machines calledlooms had rods that separated the threads to allow theweft to be inserted more easily. A piece of wood, called theshuttle, holding a spool of thread, was passed between theseparated threads. The basic principles of spinning andweaving have stayed the same until the present day,though during the industrial revolution of the18th century many ways were found of automating the

processes. With new machines such as the spinningmule, many threads could be spun atthe same time, and, with thehelp of devices like the flyingshuttle, broad pieces ofcloth could be woven atgreat speed.

ANCIENT SPINDLE

Spindles like thiswere turned by handto twist the fibers,and then allowed tohang so that thefibers were drawn into a thread. Thisexample was foundin 1921 at theancient Egyptian siteat Tel el Amarna.

SPINNING AT HOME

The spinning wheel, whichwas introduced to Europefrom India about a.d. 1200,speeded up the spinningprocess. In the 16th century,a foot treadle was added,freeing the spinners hands the left to draw out the fiber,the right to twist the t hread.

SPINNING WHEEL

This type of spinning wheel, called thewool wheel, was used in homes until about200 years ago. Spinning wheels like this,turned by hand, produced a fine yarn ofeven thickness.

Drive thread

Wool

Wooden wheel

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WATER FRAME rightAbout 250 years ago, a number of improvements weremade to spinning machines. In 1769, Englishman Richard

Arkwright introduced the water frame. The water framefirst drew out the thread, then twisted it as it was woundon to a spool or bobbin. Some ten years later, SamuelCrompton introduced the spinning mule, which

could spin up to 1,000 threadsat a time.

Spun thread

Fiber tobe spun

Bobbins

Drive wheel

CHILD LABOR aboveWith the new machinery, spinning moved out ofhomes into factories, where water or steam power

was available to work themachines. Young people wereemployed to crawl undermachines to mendbroken threads orpick up fluff.

POWER WEAVING

The first steam-powered loom appeared in1787. It could pass the shuttle across the clothover 200 times a minute. By the 1830s,steam- and water-powered weavingmachines were common infactories.

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Over 2,000years ago, the Greek scientist Thales produced smallelectric sparks by rubbing a cloth against amber, a yellow resin formed

from the sap of long-dead trees. But it was a long time before people

succeeded in harnessing this power to produce a battery a devicefor producing a steady flow of electricity. It was in 1800 thatAlessandro Volta (1745-1827) published details of the first battery.Voltas battery produced electricity using the chemical reaction

between certain solutions and metal electrodes. Other scientists,such as John Frederic Daniell (1790-

1845), improved Voltas design byusing different materials for theelectrodes. Todays batteriesfollow the same basic designbut use modern materials.

38

Batteries

LIGHTNING FLASH

In 1752, inventor BenjaminFranklin flew a kite in athunderstorm. Electricityflowed down the wet line andproduced a small spark,showing that lightning boltswere huge electric sparks.

ANIMAL ELECTRICITY

Luigi Galvani (1737-1798) found that thelegs of dead frogs twitched when they were

touched with metal rods. He thought thelegs contained animal electricity. Volta

suggested a different explanation. Animalsdo produce electricity, but the twitching ofthe frogs legs was probably caused by the

metal rods and the moisture in the legsforming a simple electric cell.

VOLTAS PILE aboveVoltas battery, or pconsisted of disks o

zinc and silver orcopper separated bpads moistened wiweak acid or saltsolution. Electricityflowed through a wlinking the top andbottom disks. Anelectrical unit, the vis named after Volt

Metalelectrodes

Fp

BUCKET CHEMISTR

To produce higher

voltages, and thus lcurrents, many cellseach consisting of aof electrodes of diffmetals, were connetogether. The commvoltaic cell consistcopper and zincelectrodes immerseweak acid. The Enginventor Cruikshancreated this troughbattery in 1800. The

metal plates were soldered back-to-back andcemented into slots in a wooden case. The cwas then filled with a dilute acid or a solutioammonium chloride, a salt.

Space filled with acid or solution

Zinc plate Handles for lifting out zinc plates Copper plate

DIPPING IN, DRYING OUT

In about 1807, W. H. Wollaston, an Englishchemist, created a battery like this. Zinc platwere fixed between the arms of U-shapedcopper plates, so that both sides of the zincwere used. The zinc plates were lifted out ofthe electrolyte to save zinc when the batterywas not in use.

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RELIABLE ELECTRICITY

The Daniell cell was the first reliable source of electricity.It produced a steady voltage over a considerable time.The cell had a copper electrode immersed in coppersulphate solution, and a zinc electrode in sulphuric acid.

The liquids were kept separate bya porous diaphragm.

Copper can actingas electrode

Porous diaphragm

RECHARGEABLE BATTERY

The French scientist GastonPlant was a pioneer of the lead-acid accumulator, which can berecharged when it runs down. Ithas electrodes of lead and leadoxide in strong sulphuric acid.

Zinc rod electrode

GASSNER CELL left

Chemist Carl Gassnerdeveloped a pioneeringtype of dry cell. He useda zinc case as thenegative (-) electrode,and a carbon rod as thepositive (+) electrode. Inbetween them was apaste of ammoniumchloride solution andPlaster of Paris.

Terminal

HUBBLE BUBBLE right

Some early batteries usedconcentrated nitric acid, but theygave off poisonous fumes. To avoidsuch hazards, the bichromate cellwas developed in the 1850s. It useda glass flask filled with chromicacid. Zinc and carbon plates wereused as electrodes.

POWERPACKS left

The so-called dry cell has amoist paste electrolyte inside a

zinc container that acts as oneelectrode. The other electrode ismanganese dioxide, connected viaa carbon rod. Small modernbatteries use a variety of materialsfor the electrodes. Mercurybatteries were the first long-life drcells. Some batteries use lithium,the lightest of metals. They have avery long life and are thereforeused in heart pacemakers.

WILHELM

ROENTGEN right

The German scientistWilhelm Roentgen

(1845-1923) discoveredX-rays in 1895. Roentgendid not understand what

these rays were so henamed them X-rays.

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The invention of photographymadeaccurate images of any object readily availablefor the first time. It sprang from a combination

of optics (see p. 28) and chemistry. Theprojection of the Suns image on a screen hadbeen explored by Arab astronomers in the

9th century a.d., and by the Chinese before them. Bythe 16th century, Italian artists such as Canaletto wereusing lenses and a camera obscura to help them makeaccurate drawings. In 1725 a German professor,Johann Heinrich Schulze, showed that the darkeningof silver nitrate solution when exposed to the Sunwas caused by light, not heat. In 1827, a light-sensitive material was applied to a metal plate and a

permanent visual record of an object was made.

40

Photography

IN THE BLACK BOX

The camera obscura(from the Latin fordark room) was atfirst just a darkenedroom or large boxwith a tiny opening atthe front and a screenor wall at the backonto which imageswere projected. Fromthe 16th century, alens was used insteadof the pinhole.

CALOTYPE IMAGE

By 1841, Englishman WilliamHenry Fox Talbot had developedthe Calotype. This is an earlyexample. It was an improvedversion of a process he hadannounced two years before,within days of Daguerresannouncement. It provided a

negative image, from whichpositives could be printed.

The daguerreotypeJoseph Nicphore Niepce took the first survivingphotograph. In 1826, he coated a pewter plate with bitumenand exposed it in a camera. Where light struck, the bitumenhardened. The unhardened areas were then dissolved awayto leave a visible image. In 1839, his one-time partner, LouisJacques Daguerre, developed a superior photographicprocess, producing the daguerreotype.

DAGUERREOTYPE IMAGE

A daguerreotype consisted of a copper platecoated with silver and treated with iodine vapor

to make it sensitive to light. It was exposed inthe camera, then the image wasdeveloped by mercury vaporand fixed with a strongsolution of ordinary salt.

Aperturerings

MAKING ADJUSTMENTS

By using screw-in lens fittingsand different sized diaphragmrings to adjust the lensaperture, as on this foldingdaguerreotype camera of the1840s, it became possible tophotograph both close-up anddistant objects in a variety oflighting conditions.

Lens andattachments

EXPOSING THE

PLATE belowIn some daguerreotypecameras, the object wasviewed through a holein the back of t he box. Then thephotographic plate, protected by a cover,

was slid into place. The lens capand the cover wereremoved to expose

the plate, thenreplaced.

Plateholder

HEAVY LOADS

Enlargements could not bemade with the earlyphotographic processes, sofor large pictures, big glassplates were used. With a datent for inspecting wet plateas they were exposed, pluswater, chemicals, and platesthe equipment could weighover 110 lb (50 kg).

Folding daguerreotypecamera

Lens cover

Lens withfocusingcontrol

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From 1839 on, the pioneers of photographyconcentrated on the use of salts of silver asthe light-sensitive material. In1851, Frederick Scott Archercreated a glass photographicplate more light-sensitive thanits predecessors. It recordednegative images of fine detail

with exposures of less than30 seconds. The plate was coatedwith a chemical mix, put in thecamera, and exposed while stillwet. It was a messy process, butgave excellent results.

41

The wet plate

Plate holder

CHEMICALS above rightA wet plate consisted of a glasssheet coated with silver saltsand a sticky material calledcollodion. It was usuallydeveloped with pyrogallic acidand fixed with sodium

thiosulphate (hypo).Chemicals were dispensedfrom small bottles.

IN AND OUT OF VIEW

This wet-plate camera wasmounted on a tripod. Therear section into which thephotographic plate wasinserted could slide towardor away from the front lenssection to increase ordecrease the image size andproduce a clear picture. Finefocusing was by means of aknob on the lens tube.

Chemicals forwet-plate process

Wet-plate negative

Modern photographyIn the 1870s dry gelatine-coatedplates covered with extremelylight-sensitive silver bromidewere developed. Soon moresensitive paper allowed manyprints to be made from anegative quickly and easily in adarkroom. In 1888 GeorgeEastman introduced a small,lightweight camera. It used filmwhich came on a roll.

CANDID CAMERA rightBy the 1920s German opticalinstrument manufacturers such as CarlZeiss were developing small precisioncameras. This 1937 single-lens reflex(SLR) Exakta model is in many ways theforerunner of a whole generation ofmodern cameras.

Film winder

Viewfinder

SLR camera

Lens

Filmwinder

PHOTOGRAPHY FOR ALL

In the early 1900sEastman developedinexpensive Brownie boxcameras such as this, andamateur photographywas born. Each time aphoto was taken, youwould wind the filmto be ready for thenext shot.

ROLL FILM

Eastmans early roll filmconsisted of a long thinstrip of paper from whichthe negative coating wasstripped and put down onglass plates beforeprinting. In 1889 celluloidroll film came on themarket. The light-sensitiveemulsion was coated ontoa see-through base sothat the stripping processwas eliminated.

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People have alwayspracticedsome form of medicine. Earlypeoples used herbs to cureillnesses. Some prehistoric

skulls have been found with round holes, probablydrilled with a trepan, a surgeons circular saw. Theancient Greeks used this operation to relieve pressureon the brain after severe head injuries. The ancient

Chinese practiced acupuncture, inserting needlesinto one part of the body to relieve pain or thesymptoms of disease in another part. But untilwell into the 19th century, a surgeons instrumentsdiffered little from early ones scalpels, forceps,various hooks, saws, and other tools to perform amputationsor to extract teeth. The first instruments used to determine

the cause of illnesses were developed in Renaissance Europefollowing the pioneering anatomical work of scientists suchas Leonardo da Vinci and Andreas Vesalius. In the

19th century, medicine developedquickly; much of the equipment

still used in medicine anddentistry today, fromstethoscopes to dentaldrills, were developed atthis time.

42

Medical inventions

PLUNGING IN

Syringes were firstused in ancient India,China, and NorthAfrica. Nowadays,syringes consist of ahollow glass or plasticbarrel and a plunger.

A syringe fitted with ablade was first used inabout 1850 by Frenchsurgeon Charles GabrielPravaz to introducefluids into veins.

NUMBING PAIN

Before the discovery ofanesthetics in 1846, surgery wasdone while the patient was stillconscious and capable of feeling

pain. Later, nitrous oxide(laughing gas), ether, or

chloroform was usedto numb pain. Thegases were inhaledvia a face mask.

YOU WONT FEEL A THING

By the 1850s, anestheticswere used by dentists to kill

pain. The first dental drillsappeared in the 1860s.

DRILLING DOWN rightThe Harrington Eradoclockwork dental drill datesfrom about 1864. When fullywound, it worked forup to 2 minutes.

FIRM BITE aboveThe first full set of false tesimilar to those used todamade in France in the 178This set of partial denturedates from about 1860.

Drill bit

Porcelainteeth

Coiled spring

Ivorylower

plate

Steam generator

Carbolic acidreservoir

Flexiblerubber tube

Mouthpieceplaced overpatientsmouth hadvalves forbreathing inand out

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SPRAY IT ON leftBy 1865 Scottish surgeon Joseph Listerhad developed an antiseptic carbolicsteam spray. It created a mist ofcarbolic acid, intended to killgerms around the operation site.This version dates from about 1875.

THROUGH THE LOOKING TUBE rightDifferent types of endoscope, for viewinginside the body without surgery, weredeveloped in the 19th century. This

1880s version used a candle asa light source.

Candle

Speculum -placed in

patients ear

Funnel forconcentratinglight

Viewing lens

UNDER PRESSURE aboveBlood pressure is measured byfeeling the pulse and slowlyapplying a measured force to theskin until the pulse disappears.The instrument that does this iscalled a sphygmomanometer andwas invented by Samuel vonBasch in 1891.

HOT UNDER THE

COLLAR? rightThese thermometers, from

about 1865, were placed in themouth (straight version) or

under the armpit (curved-endtype). Measuring the patients

temperature was not commonpractice until the early decadesof this century.

Temperaturescale in degreesFahrenheit

Reservoir ofmercury

Kink intube - to give

good fit in armpit

LIGHT-HEADED FEELING

In the 19th century, etherwas used as an anesthetic.The Letheon ether inhalerof 1847 comprised a glass jarfilled with et her-soakedsponges through which airwas drawn as the patientbreathed in.

Ether-soakedsponges

Air inlet valve

Ether vapor outletvalve

DOWN THE TUBE

In 1819 French physician RenLannec created a tube throughwhich he could hear thepatients heartbeat.

LISTENING INLannecs single-tube stethoscope was later

developed into this 1855 version of the moderndesign, with two earpieces. The stethoscope can be

used to listen to the sounds made by the heart,lungs, or blood vessels, or to the heartbeat of a

baby in the womb.

Ivory ear

TAKING THE PULSE leftIn the early 17th century,physician William Harveywas the first to show how

blood circulated around thebody. But it was not untilmuch later that the link

between the pulse, heart

activity, and health wasestablished.

Metal tubes fortransmitting thesounds. Today,tubes are made of

plastic

Cone

HOLLOW SOUNDS rightThe disk-shaped sound collector onthis 1830s wooden stethoscope would

have been used to listen to high-pitched sounds, such asthose made by the lungs,rather than low-pitchedones, such as heartbeats.

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MAKING A CONNECTI

These two men are usearly Edison equipmto make their telephocalls. Each has a diffe

arrangement - ona modern-styl

receiver and thother, a two-

piece apparatus fospeaking and listenin

All calls had to be mavia the operator.

For centuries, people have tried tosend signals over long distances usingbonfires and flashing mirrors to carry

messages. It was the Frenchman Claude

Chappe who in 1793 devised the wordtelegraph (literally, writing at a distance)to describe his message machine. Movingarms mounted on towertops signaled numbers and letters.Over the next 40 years, electric telegraphs were developed.And in 1876 Alexander Graham Bell invented the telephone,enabling speech to be sent along wires for the first time.Bells work with the deaf led to an interest in how soundsare produced by vibrations in the air. His research on adevice called the harmonic telegraph led him to discoverthat an electric current could be changed to resemble the

vibrations made by a speaking voice.This was the principle on which hebased the telephone.

44

The telephone

OPENING SPEECH

Alexander Graham Bell (18471922)developed the telephone after workingas a speech teacher with deaf people.Here he is making the first call on the

New York to Chicago line.

ALL-IN-ONE

Early models such as Bells Box telephone of187677 had a trumpetlike mouthpiece andearpiece combined. The instrument contains amembrane that vibrated when someone spokeinto the mouthpiece. The vibrations created avarying electric current in a wire, and thereceiver turned the varyingcurrent back into vibrationsthat you could hear.

Magnet Earpiece andmouthpiececombined

The telegraphThe telegraph, the forerunner of thetelephone, allowed signals to be sent alonga wire. The first telegraphs were used on therailroads to help keep track of trains. Later, telegraphwire linked major cities.

MESSAGE MACHINES

With the Morse key (left)you could send signals

made up of short dots andlong dashes. In the Cookeand Wheatstone system(right), the electric currentmade needles point atdifferent letters.

EARPI

In this earpiece of ab1878, a fluctuating ele

current passing throthe wire coil made

iron diaphragm movmake sou

Wire coil Iron diaphragm

DONT HANG

In 1877 Thomas Eddeveloped diffemouthpiece and earp

units. Models such as were hung from a speswitch that disconne

the line on clos

WIRED FOR SOU

Some early telegrcables used cop

wires sheatheglass. Overh

telegraph and phwires used

for stren

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LONG DISTANCE

CALL FOR YOU

Cradle telephones this were popular bythe 1890s. This onedates from 1937, by

which time there watransatlantic telephoservice betweenLondon and New Yo

45

EASY LISTENING

This wall-mountedtelephone of 1879 wasinvented by ThomasEdison and has amicrophone andreceiver of his design.The user had to windthe handle whilelistening. A ring of thebell indicated anincoming call or a

successful connection.

Earpiece

Mouthpiece

HANDSETS

By 1885 thetransmitter and receiverhad been combined toform a handset. At firstthis was metal, but by1929 plastic handsets

were common.

Earpiece

Mouthpiece

ITS A STICK-UP

Some candlestick-shaped phonesof the 1920s and 1930s had a

dial for calling numbers viaan automatic exchange.

Hook forearpiece

Transmittercontainingcarbon

granules,compressedand releasedby soundwaves tocreate anelectriccurrent ofvaryingstrength

Numbereddial

REPEAT THAT NUMBER

The earliest telephoneexchanges were

manual. One of the dozens of operators tookyour number and the number you wanted,

and plugged in your line wire to completethe appropriate electrical circuit.

Drawer for directory

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Sounds were recordedfor the first time in1877 on an experimental machine that ThomasEdison (18471931) hoped would translate

telephone calls into telegraph messages. Itrecorded the calls as indentations in a stripof paper passing under a stylus. Edisonnoticed that when he passed the indentedpaper through the machine again, heheard a faint echo of the originalsound. This mechanical-acousticmethod of recording continued until electrical systemsappeared in the 1920s. Magnetic principles were used todevelop tape-recording systems. These received a commercialboost, first in 1935, with the development of

magnetic plastic tape and then, in the 1960s,with the use of microelectronics (p. 62).

46

Recording

TWO IN ONE MACHINE

By 1877, Edison had created separate devices forrecording and playing back. Sounds made into a

horn caused its diaphragm to vibrate and itsstylus to create indentations on a thin sheet

of tinfoil wrapped around the recordingdrum. Putting the playback stylus and its

diaphragm in contact with the foil androtating the drum reproduced thesounds via a second diaphragm.

Mouthpiece (horn notshown)

Drive axle, threaded tomove length of foilbeneath fixed stylus

Tinfoil was wrappedaround this brass drum

PLAY IT AGAIN, SAM

The playback mechanismcomprised a stylus made ofsteel in contact with a thin

iron diaphragm. The woodenmount was flipped over so

the stylus made closecontact with t he foil as it

rotated. Vibrations from thefoil were transferred to the

diaphragm. As thediaphragm moved in and

out, it created sound waves.

Edison phonographshowing positions of

needle and horn

Cross-sectionshowingneedle oncylinder

Positionof horn

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47

IN THE GROOVE aboveEdison eventually used a continuous groove in a wax

cylinder, the depth of which varied with the intensityof the sound being recorded. These later cylinder

recordings lasted for up