invention (2005)
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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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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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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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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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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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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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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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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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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
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