History of light and color

292 Pages·2001·2.512 MB·English

by  Sean F. Johnston

A History of Light and Colour
Measurement
Science in the Shadows

A History of Light and Colour
Measurement
Science in the Shadows
Sean F Johnston
University of Glasgow, Crichton Campus, UK
Institute of Physics Publishing
Bristol and Philadelphia
(cid:1)c IOPPublishingLtd2001
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CONTENTS
PREFACE ix
1 INTRODUCTION:MAKINGLIGHTCOUNT 1
1.1 Organizationofchapters 4
1.2 Terms 9
Notes 10
2 LIGHTASALAW-ABIDINGQUANTITY 12
2.1 Beginnings 12
2.2 Alawlessfrontier 18
2.2.1 Photography:jugglingvariables 20
2.2.2 Astronomy:isolatedforays 21
2.3 Techniquesofvisualphotometry 22
2.3.1 Qualitativemethods 22
2.3.2 Comparativemethods 22
2.3.3 Physicalmethods 24
2.4 Studiesofradiantheat 24
2.5 Describingcolour 26
Notes 28
3 SEEINGTHINGS 33
3.1 Recurringthemes 34
3.2 Alteredperceptions 36
3.2.1 Astrophysicsandthescientificmeasurementoflight 37
3.2.2 Spectroscopy 41
3.2.3 Shiftingstandards:gasandelectrotechnicalphotometry 42
3.2.4 Utilitarianconnections 43
3.3 The19th-centuryphotometer 49
3.4 Prejudiceandtemptation:theproblemsinjudgingintensity 53
3.5 Quantifyinglight:n-raysversusblackbodyradiation 58
Notes 64
4 CAREERSINTHESHADOWS 72
4.1 Amateursandindependentresearch 72
4.2 Theilluminatingengineers 75
4.3 Opticalsocieties 86
AHistoryofLightandColourMeasurement
Notes 88
5 LABORATORIESANDLEGISLATION 94
5.1 Utilitarianpressures 94
5.2 ThePhysikalisch-TechnischeReichsanstalt 96
5.3 TheNationalPhysicalLaboratory 99
5.4 TheNationalBureauofStandards 102
5.5 Colouratthenationallaboratories 104
5.6 Tracingcareers 107
5.7 Weighingupthenationallaboratories 109
5.8 Industriallaboratories 111
5.9 Wartimephotometry 114
5.10 Consolidationofpractitioners 116
Notes 117
6 TECHNOLOGYINTRANSITION 125
6.1 Afashionforphysicalphotometry 125
6.1.1 Objectivity 126
6.1.2 Precision 128
6.1.3 Speed 129
6.1.4 Automation 129
6.2 Therefinementofvision 130
6.3 Shiftsofconfidence 133
6.4 Physicalphotometryforastronomers 135
6.4.1 An awkward hybrid: photographicrecording and visual
analysis 135
6.4.2 Ahalfwayhouse:photographicrecordingand
photoelectricanalysis 137
6.4.3 A‘moretroublesome’method:direct
photoelectricphotometry 139
6.5 Theriseofphotoelectricphotometry 142
6.6 Recalcitrantproblems 148
6.6.1 Talbot’slaw 148
6.6.2 Linearity 148
6.6.3 Thespectreofheterochromaticphotometry 150
Notes 151
7 DISPUTINGLIGHTANDCOLOUR 159
7.1 TheCommissionInternationaledePhotome´trie 161
7.2 TheCommissionInternationaledel’E´clairage 162
7.3 Legislativeconnections 167
7.4 Constructingcolorimetry 168
7.4.1 ColourattheCIE 168
7.4.2 Disciplinarydivisions 176
7.4.3 Differentiatingtheissues 177
7.5 Votingoncolour 179
vi
Contents
7.5.1 Configuringcompromise 180
7.5.2 Anuncertainclosure 181
Notes 184
8 MARKETINGPHOTOMETRY 191
8.1 Birthofanindustry 192
8.2 Technologicalinfluences 194
8.3 Linkingcommunities 197
8.3.1 Extensionofcommercialexpertise 200
8.3.2 Newpractitioners 201
8.4 Makingmodernity 203
8.5 Backlashtocommercialization 204
8.6 Newinstrumentsandnewmeasurements 206
8.7 Photometryforthemillions 208
8.8 Abetterimagethroughadvertising 210
Notes 213
9 MILITARIZINGRADIOMETRY 220
9.1 Themystiqueoftheinvisible 220
9.2 Militaryconnections 221
9.2.1 Britishresearch 222
9.2.2 AmericandevelopmentsduringtheSecondWorldWar 222
9.2.3 Germanexperiences 224
9.2.4 Post-warperspectives 225
9.2.5 Newresearch:beyondthen-ray 227
9.2.6 Newtechnology 227
9.3 Newcentres 229
9.4 Newcommunities 230
9.5 Newunits,newstandards 231
9.6 Commercializationofconfidentialexpertise 232
9.6.1 Newpublicknowledge 232
9.7 Anewbalance:radiometryasthe‘senior’specialism 233
Notes 233
10 AN‘UNDISCIPLINEDSCIENCE’ 237
10.1 Evolutionofpracticeandtechnique 237
10.2 Thesocialfoundationsoflight 240
10.3 Aperipheralscience? 243
10.3.1 Onbeingattheedge 243
10.3.2 Technique,technologyorappliedscience? 245
10.3.3 Attributesofperipheralscience 247
10.4 Epilogue:decliningfortunes 248
Notes 250
BIBLIOGRAPHY 255
Abbreviations 255
Periodicals 255
vii
AHistoryofLightandColourMeasurement
Organizations 257
Other 258
Sources 258
Notes 261
Bibliography 261
INDEX 272
viii
PREFACE
This book is about how light was made to count. It explores a seemingly
simplequestion: Howwasthebrightnessoflight—casuallyjudgedbyeveryone
but seldom considered a part of science before the 20th century—transformed
into a measurable and trustworthyquantity? Why did the description of colour
become meaningful to artists, dyers, industrialists and a handful of scientists?
Seekinganswersrequirestheexplorationofterritoryinthehistory,sociologyand
philosophyofscience.Lightwasmadetocountasaquantifiableentityatthesame
timeasitcametocountforsomethinginhumanterms. Measuringtheintensity
of light was fraught with difficulties closely bound up with human physiology,
contentioustechnologiesandscientificsub-cultures.
Explorations often begin with meanderings, tentative forays and more
prolongedexpeditions. Thisonerangesoveraperiodof250years, andpursues
social interactionsat everyscale. As the title hints, the subjectwas long on the
peripheryofrecognizedscience.Theillustrationsinthebookreinforcethereality
of social marginalization, too: depictionsof light-measurersare rare. Certainly
their shrouded and blackened apparatus made photography awkward; but the
reliance on human observers to make scientific measurements came to be an
embarrassmenttopractitioners. Thepractitionersremainshadowy,too, because
of the low status of their occupation, commercial reticence and—somewhat
later—militarysecrecy.
Themeasurementofbrightnesscametobeinvestedwithseveralpurposes.
It gained sporadic attention through the 18th century. Adopted alternately by
astronomers and for the utilitarian needs of the gas lighting industry from the
secondhalfofthe19thcentury,itwasappropriatedbythenascentelectriclighting
industryto‘prove’thesuperiorityoftheirtechnology. Bytheturnofthecentury
the illuminatingengineeringmovementwas becomingan organized,if eclectic,
communitypromotingresearchintothemeasurementoflightintensity.
The early 20th century development of the subject was moulded by
organizationand institutionalization. During its first two decades, new national
and industrial laboratories in Britain, America and Germany were crucial in
stabilizingpracticesandraisingconfidenceinthem.Throughtheinter-warperiod,
committeesandinternationalcommissionssoughttostandardizelightandcolour
measurementandtopromoteresearch.Suchgovernment-andindustry-supported
ix
AHistoryofLightandColourMeasurement
delegations,ratherthanacademicinstitutions,wereprimarilyresponsibleforthe
constructionofthesubject.
Along with this social organization came a new cognitive framework:
practitionersincreasinglycametointerpretthethreetopicsofphotometry(visible
lightmeasurement),colorimetry(themeasurementofcolour)andradiometry(the
measurementofinvisibleradiations)asaspectsofabroaderstudy.
This recategorization brought shifts of authority: shifts of the dominant
social group determining the direction of the subject’s evolution, and a shift
of confidence away from the central element of detection, the eye. From the
1920s,thehighlyrefinedvisualmethodsofobservationwerehurriedlyreplaced
byphysicalmeansoflightmeasurement,aprocessinitiallyamatterofscientific
fashion rather than demonstrated superiority. These non-human instruments
embodiedthenewlocusoflightandcolour,andthedatatheyproducedstabilized
thedefinitionsfurther.
The rise of automated, mechanized measurement of light and colour
introduced new communities to the subject. New photoelectric techniques
for measuring light intensity engendered new commercial instruments, a trend
that accelerated in the 1930s when photometry was taken up with mixed
success for a wide range of industrial problems. Seeds sown in those
years—namelycommercializationandindustrialapplication,thetransitionfrom
visual to physical methods and the search for fundamental limitations in light
measurement—gave the subject the form it was to retain over the next half-
century.
Nevertheless, changing usage mutated the subject. Light proved to be
a valuable quantity for military purposes during and after the Second World
War. A wholly new body of specialists—military contractors—transformed its
measurement,creatingnewtheory,newtechnology,newstandardsandnewunits
ofmeasurement.
Following this variety of players through their unfamiliar environments
illuminates the often hidden territories of scientific change. And two themes
run throughout this account of the measurement of light and colour from its
first hesitant emergence to its gradual construction as a scientific subject. The
firsttraceschangingattitudesconcerningquantification. Themathematizationof
lightwasacontentiousprocessthathingedonfindinganacceptablerelationship
betweenthemutableresponseofthehumaneyeandthemorereadilystabilized,
but less encompassing, techniques of physical measurement. The diffident
acceptanceofnewtechniquesbydifferenttechnicalcommunitiesilluminatestheir
valuesystems,interactionsandsocio-technicalevolution.
A second theme is the exploration of light measurement as a science
peripheral to the concerns of many contemporary scientists and the historians
who later studied them, and yet arguably typical of the scientific enterprise.
The lack ofattention attractedby thismarginalsubjectbelies its wide influence
throughout20th century science and technology. Light measurement straddled
the developing categories of ‘academic science’ and mere ‘invention’, and was
influenced by such distinct elements as utilitarian requirements, technological
x