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TheScienceofFingerprints

THE

SCIENCEOF

FINGERPRINTS

ClassificationandUses

UNITEDSTATESDEPARTMENTOFJUSTICE

FEDERALBUREAUOFINVESTIGATION

JohnEdgarHoover,Director

INTRODUCTIONThisbookletconcerningthestudyoffingerprintshasbeenpreparedbytheFederalBureauofInvestigationfortheuseofinterestedlawenforcementofficersandagencies,particularlythosewhichmaybecontemplatingtheinaugurationoffingerprintidentificationfiles.Itisbasedonmanyyears'experienceinfingerprintidentificationworkoutofwhichhasdevelopedthelargestcollectionofclassifiedfingerprintsintheworld.Inasmuchasthispublicationmayserveasageneralreferenceonclassificationandotherphasesoffingerprintidentificationwork,thesystemsutilizedintheIdentificationDivisionoftheFederalBureauofInvestigationaresetforthfully.Theproblemofpatterninterpretation,inparticular,isdiscussedindetail.

Criminalidentificationbymeansoffingerprintsisoneofthemostpotentfactorsinobtainingtheapprehensionoffugitiveswhomightotherwiseescapearrestandcontinuetheircriminalactivitiesindefinitely.Thistypeofidentificationalsomakespossibleanaccuratedeterminationofthenumberof



FeaturedProducts

previousarrestsandconvictionswhich,ofcourse,resultsintheimpositionofmoreequitablesentencesbythejudiciary,inasmuchastheindividualwhorepeatedlyviolatesthelawfindsitimpossibletoposesuccessfullyasafirst,orminor,offender.Inaddition,thissystemofidentificationenablestheprosecutortopresenthiscaseinthelightoftheoffender'spreviousrecord.Italsoprovidestheprobationofficers,paroleboard,andtheGovernorwithdefiniteinformationuponwhichtobasetheirjudgmentindealingwithcriminalsintheirjurisdictions.

Fromearliesttimesfingerprinting,becauseofitspeculiaradaptabilitytothefield,hasbeenassociatedinthelaymindwithcriminalidentificationtothedetrimentoftheotherusefulphasesofthescience.However,theCivilFileoftheIdentificationDivisionoftheFederalBureauofInvestigationcontainsthreetimesasmanyfingerprintsastheCriminalFile.Thesecivilfingerprintsareaninvaluableaidinidentifyingamnesiavictims,missingpersonsandunknowndeceased.Inthelattercategorythevictimsofmajordisastersmaybequicklyandpositivelyidentifiediftheirfingerprintsareonfile,thusprovidingahumanitarianbenefitnotusuallyassociatedwithfingerprintrecords.

TheregularcontributorswhovoluntarilysubmitfingerprintstotheFederalBureauofInvestigationplayamostimportantroleinthe[Pgiv]dramaofidentification.Theiractionexpandsthesizeofthefingerprintfiles,therebyincreasingthevalueofthefilestoalllawenforcementagencies.Mutualcooperationandefficiencyareresultantbyproducts.

Theuseoffingerprintsforidentificationpurposesisbasedupondistinctiveridgeoutlineswhichappearonthebulbsontheinsideoftheendjointsofthefingersandthumbs.Theseridgeshavedefinitecontoursandappearinseveralgeneralpatterntypes,eachwithgeneralandspecificvariationsofthepattern,dependentontheshapeandrelationshipoftheridges.Theoutlinesoftheridgesappearmostclearlywheninkedimpressionsaretakenuponpaper,sothattheridgesareblackagainstawhitebackground.Thisresultisachievedbytheinkadheringtothefrictionridges.Impressionsmaybemadewithblood,dirt,greaseoranyotherforeignmatterpresentontheridges,orthesalinesubstanceemittedbytheglandsthroughtheductsorporeswhichconstitutetheiroutlets.Thebackgroundormediummaybepaper,glass,porcelain,wood,cloth,wax,putty,silverware,oranysmooth,nonporousmaterial.

Ofallthemethodsofidentification,fingerprintingalonehasprovedtobebothinfallibleandfeasible.Itssuperiorityovertheoldermethods,suchasbranding,tattooing,distinctiveclothing,photography,andbodymeasurements(Bertillonsystem),hasbeendemonstratedtimeaftertime.Whilemanycasesofmistakenidentificationhaveoccurredthroughtheuseoftheseoldersystems,todatethefingerprintsofnotwoindividualshavebeenfoundtobeidentical.

Thebackgroundandhistoryofthescienceoffingerprintsconstituteaneloquentdramaofhumanlives,ofgoodandofevil.Nothing,Ithink,hasplayedapartmoreexcitingthanthatenactedbythefascinatingloops,whorls,andarchesetchedonthefingersofahumanbeing.

J.EDGARHOOVER,Director.

[Pgv]

CONTENTS

Chapter PageIntroduction iiiI.TheIdentificationDivisionoftheFBI 1II.TypesofPatternsandTheirInterpretation 5III.QuestionablePatterns 71IV.TheClassificationFormulaandExtensions 87V.ClassificationofScarredPatternsAmputationMissingatBirth 98VI.FilingSequence 103VII.SearchingandReferencing 109VIII.HowToTakeInkedFingerprints 114IX.ProblemsintheTakingofInkedFingerprints 118X.ProblemsandPracticesinFingerprintingtheDead 131XI.EstablishmentofaLocalFingerprintIdentificationBureau 160XII.LatentImpressions 173XIII.PowderingandLiftingLatentImpressions 175XIV.ChemicalDevelopmentofLatentImpressions 177XV.TheUseoftheFingerprintCamera 184XVI.PreparationofFingerprintChartsforCourtTestimony 190



LatentFingerprintKit$29.95

XVII.UnidentifiedLatentFingerprintFile 194

CHAPTERI

TheIdentificationDivisionoftheFBI

TheFBIIdentificationDivisionwasestablishedin1924whentherecordsoftheNationalBureauofCriminalInvestigationandtheLeavenworthPenitentiaryBureauwereconsolidatedinWashington,D.C.Theoriginalcollectionofonly810,000fingerprintcardshasexpandedintomanymillions.TheestablishmentoftheFBIIdentificationDivisionresultedfromthefactthatpoliceofficialsoftheNationsawtheneedforacentralizedpoolingofallfingerprintcardsandallarrestrecords.

TheFederalBureauofInvestigationoffersidentificationservicefreeofchargeforofficialusetoalllawenforcementagenciesinthiscountryandtoforeignlawenforcementagencieswhichcooperateintheInternationalExchangeofIdentificationData.Throughthiscentralizationofrecordsitisnowpossibleforanofficertohaveavailableapositivesourceofinformationrelativetothepastactivitiesofanindividualinhiscustody.ItistheBureau'spresentpolicytogivepreferredattentiontoallarrestfingerprintcardssinceitisrealizedthatspeedisessentialinthisservice.

InorderthattheFBIIdentificationDivisioncanprovidemaximumservicetoalllawenforcementagencies,itisessentialthatstandardfingerprintcardsandotherformsfurnishedbytheFBIbeutilized.Fingerprintsmustbeclearanddistinctandcompletenameanddescriptivedatarequiredontheformshouldbefurnishedinallinstances.Fingerprintsshouldbesubmittedpromptlysincedelaymightresultinreleaseofafugitivepriortonotificationtothelawenforcementagencyseekinghisapprehension.

WhenitisknowntoalawenforcementagencythatasubjectunderarrestisanemployeeoftheU.S.GovernmentoramemberoftheArmedForces,anotationshouldbeplacedinthespacefor"occupation"onthefrontofthefingerprintcard.Datasuchaslocationofagencyormilitarypostofassignmentmaybeaddedbesidethespacereservedforthephotographonthereversesideofthecard.

Manyinstanceshavebeenobservedwhereanindividualisfingerprintedbymorethanonelawenforcementagencyforthesamearrest.ThisduplicatesubmissionoffingerprintscanbeeliminatedbyplacinganotationonthefirstsetoffingerprintssenttotheFBIrequestingcopiesoftherecordforotherinterestedlawenforcementagencies,therebyeliminatingsubmissionoffingerprintsbythelatteragencies.

IfaphotographisavailableatthetimefingerprintsaresubmittedtotheFBIIdentificationDivision,itshouldbeidentifiedonthereversesidewiththeindividual'scompletename,nameofthedepartmentsubmitting,thedepartment'snumber,anditshouldbesecurelypastedinthespaceprovidedonthefingerprintcard.Ifaphotographistobesubmittedatalaterdate,itshouldbehelduntiltheidentificationrecordor"norecord"replyfromtheFBIisreceivedinorderthatFBInumberorfingerprintclassificationcanbeaddedtothereversesideofthephotographforassistanceoftheIdentificationDivisioninrelatingittotheproperrecord.

TheFBInumber,ifknown,andanyrequestforspecialhandling,suchascollectwireortelephonereply,shouldbeindicatedonthefingerprintcardintheappropriatespace.Suchnotationseliminatetheneedforanaccompanyingletterofinstructions.

Asindicated,theFBI'sserviceisgivenwithoutcosttoregularlyconstitutedlawenforcementagenciesandofficers.Suppliesoffingerprintcardsandselfaddressed,frankedenvelopeswillbeforwardedupontherequestofanylawenforcementofficer.Thefollowingtypesofcardsandformsareavailable:Criminal(FormFD249),usedforbotharrestandinstitutionrecordsApplicant(FormFD258)PersonalIdentification(FormFD353)DeathSheet(FormR88)DispositionSheet(FormR84)WantedNotice(Form112)RecordofAdditionalArrest(Form11).AnorderformforidentificationsuppliesappearseachmonthwiththeinserttotheFBILawEnforcementBulletin.

Inadditiontoitscriminalidentificationactivities,theBureau'sIdentificationDivisionmaintainsseveralauxiliaryservices.Nottheleastoftheseisthesystemwherebyfugitivesareidentifiedthroughthecomparisonoffingerprintswhicharereceivedcurrently.Whenalawenforcementofficerdesirestheapprehensionofafugitiveandthefingerprintsofthatindividualareavailable,itisnecessaryonlythatheinformtheBureauofthisfactsoawantednoticemaybeplacedinthefugitive'srecord.Thisinsuresimmediatenotificationwhenthefugitive'sfingerprintsarenextreceived.

ThefugitiveserviceisamplifiedbytheBureau'sactionintransmittingamonthlybulletintoalllawenforcementagencieswhichforwardfingerprintsforitsfiles.Inthisbulletinarelistedthenames,descriptions,andfingerprintclassificationsofpersonswantedforoffensesofamoreseriouscharacter.Thisinformationfacilitatespromptidentificationsofindividualsarrestedforanyoffenseorotherwiselocatedbythosereceivingthebulletin.

MissingpersonsnoticesarepostedintheIdentificationfilessothatanyincomingrecordonthemissingpersonwillbenoted.Noticesarepostedbothbyfingerprintcardandbyname,orbynamealoneiffingerprintsarenotavailable.Thefullname,date,andplaceofbirth,completedescriptionandphotographofamissingpersonshouldbeforwarded,alongwithfingerprints,ifavailable.Uponreceiptofpertinentinformation,thecontributingagencyisadvisedimmediately.AsectiononmissingpersonsiscarriedasaninsertintheLawEnforcementBulletin.

TheFBIIdentificationDivisionhasarrangedwiththeidentificationbureausofmanyforeigncountriesto



exchangecriminalidentifyingdataincasesofmutualinterest.FingerprintsandarrestrecordsofpersonsarrestedinthiscountryareroutedtotheappropriateforeignbureausincaseswhentheinterestedagencyintheUnitedStateshasreasontobelieveanindividualincustodymayhavearecordinorbewantedbytheothernation.Similarly,fingerprintsarereferredtotheFederalBureauofInvestigationbyforeignbureauswhenitseemsarecordmaybedisclosedbyasearchoftheBureau'srecords.Numerousidentifications,includinganumberoffugitives,havebeeneffectedinthismanner,anditisbelievedthatthecompletedevelopmentofthisprojectwillprovidemoreeffectivelawenforcementthroughouttheworld.Whenthefactsindicateanindividualmayhavearecordinanothercountry,andthecontributorsubmitsanextrasetofhisfingerprints,theyaretransmittedbythisBureautotheproperauthorities.

Inveryrarecasespersonswithouthandsarearrested.AfileonfootprintsismaintainedintheIdentificationDivisiononsuchindividuals.

Inviewofthefactthatmanyindividualsintheunderworldareknownonlybytheirnicknames,theIdentificationDivisionhasforyearsmaintainedacardindexfilecontaininginalphabeticalorderthenicknamesappearingonfingerprintcards.Whenrequestingasearchofthenicknamefile,itisdesiredthatallpossibledescriptivedatabefurnished.

TheLatentFingerprintSectionhandleslatentprintwork.ArticlesofevidencesubmittedbylawenforcementagenciesareprocessedforthedevelopmentoflatentimpressionsintheLatentFingerprintSection.Inaddition,photographs,negatives,andliftsoflatentsarescrutinizedforprintsofvalueforidentificationpurposes.PhotographsoftheprintsofvaluearealwayspreparedfortheFBI'sfilesandareavailableforcomparisonsforanindefiniteperiod.ShouldthelawenforcementagencydesireadditionalcomparisonsitneedsonlyadvisetheFBIIdentificationDivision,attentionLatentFingerprintSection,andeithernameorsubmittheprintsofthenewsuspect.Itisnotnecessarytoresubmittheevidence.Whennecessary,afingerprintexpertwilltestifyinlocalcourtastohisfindings.Shouldadepartmenthaveanyspecialproblemsinvolvingthedevelopmentorpreservationoffingerprintsatacrimescene,theexpertsareavailableforsuggestions.InconnectionwiththeLatentFingerprintSectionthereismaintainedageneralappearancefileofmanyconfidencegameoperators.Searchesinthisfilewillbemadeuponrequest.Infurnishingdataonasuspect,theagencyshouldmakesurethatcompletedescriptivedataissentin.Photographsandothermaterialonindividualswhomaybeidenticalwiththosebeingsoughtwillbefurnishedtotheinteresteddepartments.

DuringtheyearsmanypersonshavevoluntarilysubmittedtheirfingerprintstotheIdentificationDivisionforpossibleuseinthecaseofanemergency.Thesecardsarenotfiledwiththecriminalfingerprintsbutaremaintainedseparately.Suchprintsshouldbetakenonthestandard[Pg4]fingerprintformentitled"PersonalIdentification"(FormFD353).NoanswerisgiventoPersonalIdentificationfingerprintcards.

ThefingerprintrecordsoftheFBIIdentificationDivisionareusedliberallynotonlybypoliceagenciestoobtainpreviousfingerprinthistoriesandtoascertainwhetherpersonsarrestedarewantedelsewhere,butbyprosecutorstowhomtheinformationfromtheBureau'sfilesmayprovetobevaluableinconnectionwiththeprosecutionofacase.Theserecordsarelikewiseoffrequentvaluetothejudgeforhisconsiderationinconnectionwiththeimpositionofsentence.Obviously,theendsofjusticemaybeservedmostequitablywhenthepastfingerprintrecordofthepersonontrialcanbemadeknowntothecourt,orinformationmaybefurnishedtotheeffectthatthedefendantisofhithertounblemishedreputation.

ItshouldbeemphasizedthatFBIidentificationrecordsarefortheOFFICIALuseoflawenforcementandgovernmentalagenciesandmisuseofsuchrecordsbydisseminatingthemtounauthorizedpersonsmayresultincancellationofFBIidentificationservices.

CHAPTERII

TypesofPatternsandTheirInterpretation

Typesofpatterns

Fingerprintsmayberesolvedintothreelargegeneralgroupsofpatterns,eachgroupbearingthesamegeneralcharacteristicsorfamilyresemblance.Thepatternsmaybefurtherdividedintosubgroupsbymeansofthesmallerdifferencesexistingbetweenthepatternsinthesamegeneralgroup.Thesedivisionsareasfollows:

I.ARCH II.LOOP III.WHORL

a.Plainarch. a.Radialloop. a.Plainwhorl.

b.Tentedarch. b.Ulnarloop. b.Centralpocketloop.

c.Doubleloop.

d.Accidentalwhorl.

Illustrations1to10areexamplesofthevarioustypesoffingerprintpatterns.



[Figs.110]

Interpretation



Beforepatterndefinitioncanbeunderstood,itisnecessarytounderstandthemeaningofafewtechnicaltermsusedinfingerprintwork.

Thepatternareaistheonlypartofthefingerimpressionwithwhichweareconcernedinregardtointerpretationandclassification.Itispresentinallpatterns,ofcourse,butinmanyarchesandtentedarchesitisimpossibletodefine.Thisisnotimportant,however,astheonlypatternsinwhichweneedtodefinethepatternareaforclassificationpurposesareloopsandwhorls.Inthesetwopatterntypesthepatternareamaybedefinedasfollows:

Thepatternareaisthatpartofalooporwhorlinwhichappearthecores,deltas,andridgeswithwhichweareconcernedinclassifying.

Thepatternareasofloopsandwhorlsareenclosedbytypelines.

Typelinesmaybedefinedasthetwoinnermostridgeswhichstartparallel,diverge,andsurroundortendtosurroundthepatternarea.

Figure11isatypicalloop.LinesAandB,whichhavebeenemphasizedinthissketch,arethetypelines,startingparallel,divergingatthelineCandsurroundingthepatternarea,whichisemphasizedinfigure12byeliminatingalltheridgeswithinthepatternarea.

[Figs.1112]

Figures72through101shouldbestudiedforthelocationoftypelines./p>

Typelinesarenotalwaystwocontinuousridges.Infact,theyaremoreoftenfoundtobebroken.Whenthereisadefinitebreakinatypeline,theridgeimmediatelyoutsideofitisconsideredasitscontinuation,asshownbytheemphasizedridgesinfigure13.

[Fig.13]

Sometimestypelinesmaybeveryshort.Caremustbeexercisedintheirlocation.Noticetherighttypelineinfigure14.



[Fig.14]

Whenlocatingtypelinesitisnecessarytokeepinmindthedistinctionbetweenadivergenceandabifurcation(fig.15).

[Fig.15]

Abifurcationistheforkingordividingofonelineintotwoormorebranches.

Adivergenceisthespreadingapartoftwolineswhichhavebeenrunningparallelornearlyparallel.

Accordingtothenarrowmeaningofthewordsinfingerprintparlance,asingleridgemaybifurcate,butitmaynotbesaidtodiverge.Therefore,withoneexception,thetwoforksofabifurcationmayneverconstitutetypelines.Theexceptioniswhentheforksrunparallelafterbifurcatingandthendiverge.Insuchacasethetwoforksbecomethetwoinnermostridgesrequiredbythedefinition.Inillustration16,theridgesmarked"AA"aretypelineseventhoughtheyproceedfromabifurcation.Infigure17,however,theridgesAAarenotthetypelinesbecausetheforksofthebifurcationdonotrunparallelwitheachother.Instead,theridgesmarked"T"arethetypelines.

[Fig.16]



[Fig.17]

Anglesareneverformedbyasingleridgebutbytheabuttingofoneridgeagainstanother.Therefore,anangularformationcannotbeusedasatypeline.Infigure18,ridgesAandBjoinatanangle.RidgeBdoesnotrunparallelwithridgeDridgeAdoesnotdiverge.RidgesCandD,therefore,arethetypelines.

[Fig.18]

FocalpointsWithinthepatternareasofloopsandwhorlsareenclosedthefocalpointswhichareusedtoclassifythem.Thesepointsarecalleddeltaandcore.

Thedeltaisthatpointonaridgeatorinfrontofandnearestthecenterofthedivergenceofthetypelines.

Itmaybe:

Abifurcation

Anabruptendingridge

Adot

Ashortridge

Ameetingoftworidges

Apointonthefirstrecurvingridgelocatednearesttothecenterandinfrontofthedivergenceofthetypelines.

Theconceptofthedeltamayperhapsbeclarifiedbyfurtherexposition.Websterfurnishesthefollowingdefinition:"(1)DeltaisthenameofthefourthletteroftheGreekalphabet(equivalenttotheEnglishD)fromthePhoeniciannameforthecorrespondingletter.TheGreekscalledthealluvialdepositatthemouthoftheNile,fromitsshape,theDeltaoftheNile.(2)Atractoflandshapedliketheletter"delta,"especiallywhenthelandisalluvial,andenclosedwithintwoormoremouthsofariver,astheDeltaoftheGanges,oftheNile,oftheMississippi"(fig.19).



[Fig.19]

Whentheuseoftheword"delta"inphysicalgeographyisfullygrasped,itsfitnessasappliedinfingerprintworkwillbecomeevident.Riverswearawaytheirbanksandcarrythemalongintheirwatersintheformofafinesediment.Astheriversunitewithseasorlakes,theonwardsweepofthewaterislessened,andthesediment,becomingcomparativelystill,sinkstothebottomwherethereisformedashoalwhichgraduallygrows,asmoreandmoreisprecipitated,untilatlengthaportionoftheshoalbecomeshigherthantheordinarylevelofthestream.Thereisasimilaritybetweentheuseoftheword"delta"inphysicalgeographyandinfingerprints.Theislandformedinfrontofthedivergingsidesofthebankswherethestreamemptiesatitsmouthcorrespondstothedeltainfingerprints,whichisthefirstobstructionofanynatureatthepointofdivergenceofthetypelinesinfrontofornearestthecenterofthedivergence.

Infigure20,thedotmarked"delta"isconsideredasthedeltabecauseitisthefirstridgeorpartofaridgenearestthepointofdivergenceofthetwotypelines.Ifthedotwerenotpresent,pointBonridgeC,asshowninthefigure,wouldbeconsideredasthedelta.Thiswouldbeequallytruewhethertheridgeswereconnectedwithoneofthetypelines,bothtypelines,ordisconnectedaltogether.Infigure20,withthedotasthedelta,thefirstridgecountisridgeC.Ifthedotwerenotpresent,pointBonridgeCwouldbeconsideredasthedeltaandthefirstcountwouldberidgeD.ThelinesXXandYYarethetypelines,notXAandYZ.

[Fig.20]

Infigures21to24,theheavylinesAAandBBaretypelineswiththedeltaatpointD.



[Figs.2124]

Figure25showsridgeAbifurcatingfromthelowertypelineinsidethepatternarea.BifurcationsarealsopresentwithinthispatternatpointsBandC.Thebifurcationatthepointmarked"delta"istheonlyonewhichfulfillsallconditionsnecessaryforitslocation.Itshouldbeunderstoodthatthedivergingtypelinesmustbepresentinalldeltaformationsandthatwhereveroneoftheformationsmentionedinthedefinitionofadeltamaybe,itmustbelocatedmidwaybetweentwodivergingtypelinesatorjustinfrontofwheretheydivergeinordertosatisfythedefinitionandqualifyasadelta.

[Fig.25]

Whenthereisachoicebetweentwoormorepossibledeltas,thefollowingrulesgovern:

Thedeltamaynotbelocatedatabifurcationwhichdoesnotopentowardthecore.

Infigure26,thebifurcationatEisclosertothecorethanthebifurcationatD.However,Eisnotimmediatelyinfrontofthedivergenceofthetypelinesanditdoesnotopentowardthecore.AAandBBaretheonlypossibletypelinesinthissketchanditfollows,therefore,thatthebifurcationatDmustbecalledthedelta.ThefirstridgecountwouldberidgeC.



[Fig.26]

Whenthereisachoicebetweenabifurcationandanothertypeofdelta,thebifurcationisselected.

Aproblemofthistypeisshowninfigure27.Thedot,A,andthebifurcationareequallyclosetothedivergenceofthetypelines,butthebifurcationisselectedasthedelta.Theridgesmarked"T"arethetypelines.

[Fig.27]

Whentherearetwoormorepossibledeltaswhichconformtothedefinition,theonenearestthecoreischosen.

Printsaresometimesfoundwhereinasingleridgeentersthepatternareawithtwoormorebifurcationsopeningtowardthecore.Figure28isanexampleofthis.RidgeAentersthepatternareaandbifurcatesatpointsXandD.ThebifurcationatD,whichistheclosertothecore,is[Pg13]thedeltaandconformstotherulefordeltas.AAandBBarethetypelines.Abifurcationwhichdoesnotconformtothedefinitionshouldnotbeconsideredasadeltairrespectiveofitsdistancefromthecore.

[Fig.28]

Thedeltamaynotbelocatedinthemiddleofaridgerunningbetweenthetypelinestowardthecore,butatthenearerendonly.



Thelocationofthedeltainthiscasedependsentirelyuponthepointoforiginoftheridgerunningbetweenthetypelinestowardthecore.Iftheridgeisentirelywithinthepatternarea,thedeltaislocatedattheendnearerthepointofdivergenceofthetypelines.Figure29isanexampleofthiskind.

[Fig.29]

Iftheridgeentersthepatternareafromapointbelowthedivergenceofthetypelines,however,thedeltamustbelocatedattheendnearerthecore.RidgeAinfigure30isofthistype.

[Fig.30]

Infigure31,AAandBBarethetypelines,withthedotasthedelta.Thebifurcationscannotbeconsideredastheydonotopentowardthecore.

[Fig.31]

Infigure32,thedotcannotbethedeltabecauselineDcannotbeconsideredasatypeline.ItdoesnotrunparalleltotypelineAAatanypoint.ThesamereasonpreventslineEfrombeingatypeline.TheendofridgeEistheonlypossibledeltaasitisapointontheridgenearesttothecenterofdivergenceofthetypelines.Theothertypelineis,ofcourse,BB.



[Fig.32]

Thedeltaisthepointfromwhichtostartinridgecounting.Inthelooptypepatterntheridgesinterveningbetweenthedeltaandthecorearecounted.Thecoreisthesecondofthetwofocalpoints.

Thecore,asthenameimplies,istheapproximatecenterofthefingerimpression.Itwillbenecessarytoconcernourselveswiththecoreofthelooptypeonly.Thefollowingrulesgoverntheselectionofthecoreofaloop:

Thecoreisplaceduponorwithintheinnermostsufficientrecurve.

Whentheinnermostsufficientrecurvecontainsnoendingridgeorrodrisingashighastheshouldersoftheloop,thecoreisplacedontheshoulderoftheloopfartherfromthedelta.

Whentheinnermostsufficientrecurvecontainsanunevennumberofrodsrisingashighastheshoulders,thecoreisplacedupontheendofthecenterrodwhetherittouchestheloopingridgeornot.

Whentheinnermostsufficientrecurvecontainsanevennumberofrodsrisingashighastheshoulders,thecoreisplacedupontheendofthefartheroneofthetwocenterrods,thetwocenterrodsbeingtreatedasthoughtheywereconnectedbyarecurvingridge.

Theshouldersofalooparethepointsatwhichtherecurvingridgedefinitelyturnsinwardorcurves.

Figures33to38reflectthefocalpointsofaseriesofloops.Infigure39,therearetworods,buttherodmarked"A"doesnotriseashighastheshoulderlineX,sothecoreisatB.



[Figs.3339]

Figures40to45illustratetherulethatarecurvemusthavenoappendageabuttinguponitatarightanglebetweentheshouldersandontheoutside.Ifsuchanappendageispresentbetweentheshouldersofaloop,thatloopisconsideredspoiledandthenextloopoutsidewillbeconsideredtolocatethecore.Ineachofthefigures,thepointCindicatesthecore.Appendageswillbefurtherexplainedinthesectionconcerningloops.



[Figs.4045]

Figures46to48reflectinterlockingloopsatthecenter,whilefigure49hastwoloopssidebysideatthecenter.Inallthesecasesthetwoloopsareconsideredasone.Infigure46,whentheshoulderlineXXisdrawnitisfoundtocrossexactlyatthepointofintersectionofthetwoloops.Thetwoloopsareconsideredone,withonerod,thecorebeingplacedatC.Infigure47,theshoulderlineXXisabovethepointofintersectionofthetwoloops.Thetwoareconsideredasone,withtworods,thecorebeingatC.Infigure48,theshoulderlineXXisbelowthepointofintersectionoftheloops.Againthetwoaretreatedasone,withtworods,thecorebeingplacedatC.Infigure49,thetwoaretreatedasone,withtworods,thecorebeingplacedatC.



[Figs.4649]

Infigure50,thedeltaisformedbyabifurcationwhichisnotconnectedwitheitherofthetypelines.ThefirstridgecountinthisinstanceisridgeC.Ifthebifurcationwerenotpresent,thedeltawouldbeapointonridgeCandthefirstridgecountwouldberidgeD.Infigure51,theridgewhichbifurcatesisconnectedwiththelowertypeline.ThedeltainthiswouldbelocatedonthebifurcationasdesignatedandthefirstridgecountwouldberidgeC.Figure52reflectsthesametypeofdeltashowninthepreviousfigureinthattheridgeisbifurcatingfromatypelineandthenbifurcatesagaintoformthedelta.

[Figs.5052]

Awhitespacemustintervenebetweenthedeltaandthefirstridgecount.Ifnosuchintervalexists,thefirstridgemustbedisregarded.Infigures53and54,thefirstridgebeyondthedeltaiscounted.Infigure55,itisnotcountedbecausethereisnointervalbetweenitandthedelta.Noticethattheridgerunningfromthedeltatowardthecoreisinastraightlinebetweenthem.Ifitwerenot,ofcourse,anintervalwouldinterveneasinfigures53and54.



[Figs.5355]

Theloop

Infingerprints,aswellasintheusualapplicationoftheword"loop,"therecannotbealoopunlessthereisarecurveorturningbackonitselfofoneormoreoftheridges.Otherconditionshavetobeconsidered,however.Apatternmustpossessseveralrequisitesbeforeitmaybeproperlyclassifiedasaloop.Thistypeofpatternisthemostnumerousofallandconstitutesabout65percentofallprints.[Pg19]

Aloopisthattypeoffingerprintpatterninwhichoneormoreoftheridgesenteroneithersideoftheimpression,recurve,touchorpassanimaginarylinedrawnfromthedeltatothecore,andterminateortendtoterminateonortowardthesamesideoftheimpressionfromwhencesuchridgeorridgesentered.

Essentialsofaloop

Asufficientrecurve.

Adelta.

Aridgecountacrossaloopingridge.

Asufficientrecurvemaybedefinedasthatpartofarecurvingridgebetweentheshouldersofaloop.Itmustbefreeofanyappendagesabuttingupontheoutsideoftherecurveatarightangle.

AppendagesSomeexplanationisnecessaryoftheimportanceattachedtoappendages.Muchcaremustbeexercisedininterpretingappendagesbecausetheysometimeschangetheshapeoftherecurvingridgetowhichtheyareconnected.Forexample,aloopwithanappendageabuttinguponitsrecurvebetweentheshouldersandatrightangles,asinillustration56,willappearsometimesasinillustration57withtherecurvetotallydestroyed.Forfurtherexamplesseefigures161to184.

[Figs.5657]



Thesameistrueofawhorlrecurve,asinfigures58and59.

[Figs.5859]

Itisnecessary,therefore,toconsiderandclassifyfigures56and58asiftheyactuallyappearedasinfigures57and59.

Infigure60,thereisaridgemarked"A"whichentersononesideoftheimpressionand,afterrecurving,passesanimaginarylinedrawnfromthecoreCtodeltaD,andterminatesonthesamesideoftheimpressionfromwhichitentered,marked"B",thusfulfillingalltheconditionsrequiredinthedefinitionofaloop.XandYarethetypelines.Itwillbenotedinfigure61thatthereisaridgewhichentersononesideofthe[Pg20]impression,recurves,andpassesanimaginarylinedrawnfromthedeltatothecore.Itdoesnotterminateonthesidefromwhichitenteredbuthasatendencytodoso.Inthiscase,alltherequirementsoftheloophavebeenmet,andconsequentlyitisclassifiedassuch.

[Fig.60]

[Fig.61]

Figure62showsaridgeenteringononesideoftheimpression,recurving,andpassingbeyondanimaginarylinedrawnfromthedeltatothecore,althoughoppositefromthepatternshowninfigure61.Afterpassingtheimaginaryline,therecurvingridgedoesnotterminateonthesideoftheimpression



fromwhichitentered,butithasatendencytodoso,andthepatternis,therefore,aloop.

[Fig.62]

Infigure63,aridgeentersononesideoftheimpressionandthenrecurves,containingtworodswithinit,eachofwhichrisesashighastheshoulderoftheloop.Fromourstudyofcores,weknowthatthetopoftherodmoredistantfromthedeltaisthecore,buttherecurvingridgedoesnotpasstheimaginaryline.Forthatreasonthepatternisnotclassifiedasaloop,butisgiventhepreferentialclassificationofatentedarchduetothelackofoneofthelooprequisites.Theproperlocationofthecoreanddeltaisofextremeimportance,foranerrorinthelocationofeithermightcausethispatterntobeclassifiedasaloop.[Pg21]

[Fig.63]

Figure64reflectsasimilarcondition.

[Fig.64]

Infigure65,thereisaloopingridgeAwhichentersononesideoftheimpression.TheridgesBandCarethetypelines.Asdeterminedbyrulesalreadystated,thelocationofthecoreandthelocationofthedelta[Pg22]areshown,andifanimaginarylinewereplacedonthecoreanddelta,therecurvingridgeAwouldcrossit.Thisisanotherfigureshowingaridgewhichdoesnotterminateonthesideoftheimpressionfromwhichitenteredbuttendstodoso,and,therefore,isconsideredasaloop.



[Fig.65]

Infigure66,wehaveaprintwhichissimilarinmanyrespectstotheonedescribedintheprecedingparagraph,butheretherecurvingridgeAcontinuesandtendstoterminateontheoppositesideoftheimpressionfromwhichitentered.Forthisreasonthepatternisnotaloop,butatentedarch.Therecurvingridgemusttouchorpasstheimaginarylinebetweendeltaandcoreandatleasttendtopassouttowardthesidefromwhichitentered,sothataridgecountofatleastonecanbeobtained.

[Fig.66]

Figure67showsaridgewhichentersononesideoftheimpressionand,afterflowingtowardthecenter,turnsorloopsonitselfandterminatesonthesamesidefromwhenceitentered.Thispatternwouldbeclassifiedasaloop.Thispatternshouldbedistinguishedfromthepatternappearinginfigure139.Carefulstudyofthepatterninfigure67revealsthatthecoreislocatedatCandthedeltaD.Theimaginarylinebetweenthesepointswillbecrossedbytheridgeformingaloop.Infigure139,thecoreislocatedontherecurveandanimaginarylinebetweenthedeltaandthecoredoesnotcrossaloopingridge.Figure139isthusclassifiedasatentedarch,aswillbeseenlater.

[Fig.67]

Figure68showsatthecenteroftheprintaridgewhichformsapocket.ItwillbenoticedthatridgeAdoesnotbeginontheedgeoftheprint,butthisisofnosignificance.TheridgeAwithinthepatternarearecurvesorloops,passingtheimaginarylinebetweenthedeltaandthecore,andtendstoterminatetowardthesamesideoftheimpressionfromwhenceitentered.Thisisalooppatternpossessingalloftherequirements.[Pg23]



[Fig.68]

Infigures69and70,itwillbeobservedthatthereisaridgeenteringononesideofthepatternwhichrecurvesandthenturnsbackonitself.Thesepatternsaredifferentfromanyotherswhichhavebeenshowninthisrespectbutareclassifiedasloops.Ineachofthepatternsthecoreanddeltaaremarked"C"and"D".ThereadershouldtracethetypelinesinordertoascertainwhythedeltaislocatedatpointD,andthenapplythedeltarule.

[Fig.69]

[Fig.70]

Figure71isanexampleofloopsastheyappearontherolledimpressionportionofafingerprintcard.[Pg24]



[Fig.71]

[Enlarge]

Ridgecounting

Thenumberofridgesinterveningbetweenthedeltaandthecoreisknownastheridgecount.ThetechnicalemployeesoftheFederalBureauofInvestigationcounteachridgewhichcrossesortouchesanimaginarylinedrawnfromthedeltatothecore.Neitherdeltanorcoreiscounted.Aredlineuponthereticuleofthefingerprintglassisusedtoinsureabsoluteaccuracy.Intheeventthereisabifurcationofaridgeexactlyatthepointwheretheimaginarylinewouldbedrawn,tworidgesarecounted.Wherethelinecrossesanisland,bothsidesarecounted.Fragmentsanddotsarecountedasridgesonlyiftheyappeartobeasthickandheavyastheotherridgesintheimmediatepattern.Variationsininkingandpressuremust,ofcourse,beconsidered.

Figures72to97andfigures98to101showvariouslooppatterns.Thereadershouldexamineeachonecarefullyinordertostudythecoresanddeltasandtoverifythecountwhichhasbeenplacedbeloweachpattern.[Pg25]



[Pg26]



[Pg27]



[Pg28]



[Pg29]



[Figs.72101]

[Pg30]

Figure102isasketchreflectingthevarioustypesofridgeswhichtheclassifierwillencounterwhenengagingincountinglooppatterns.



[Fig.102]

Infigure103,thelighterlinesarecausedbythesplittingorfrayingoftheridges.Sometimesingraineddirtwillcauseasimilarconditionbetweentheridges.Theselinesarenotconsideredridgesandshouldnotbecounted.

[Fig.103]

Infigure104,thedotisnotthedeltabecauseitisnotasthickandheavyastheotherridgesandmightnotbepresentifthefingerwerenotperfectlyinkedandprinted.

[Fig.104]



Whenthecoreislocatedonaspikewhichtouchestheinsideoftheinnermostrecurvingridge,therecurveisincludedintheridgecountonlywhenthedeltaislocatedbelowalinedrawnatrightanglestothespike.

Figures105and106areexamplesofthisrule.

[Figs.105106]

IfthedeltaislocatedinareasA,therecurvingridgeiscounted.

IfthedeltaislocatedinareasB,therecurvingridgeisnotcounted.

[Pg31]

Radialandulnarloops

Theterms"radial"and"ulnar"arederivedfromtheradiusandulnabonesoftheforearm.Loopswhichflowinthedirectionoftheulnabone(towardthelittlefinger)arecalledulnarloopsandthosewhichflowinthedirectionoftheradiusbonearecalledradialloops.

Fortestpurposes,fingersoftherighthandmaybeplacedonthecorrespondingprintoftherighthandappearinginfigure71,anditwillbenoticedthatthesideofeachfingerwhichisnearertothethumbonthehandisalsonearertothethumbonthefingerprintcard.Placethefingersofthelefthandonthecorrespondingprintsofthelefthandshowninfigure71.Itwillbenoticedthatthearrangementoftheprintsonthecardisthereverseofthearrangementofthefingersonthehand.Theclassificationofloopsisbasedonthewaytheloopsflowonthehand(notthecard),sothatonthefingerprintcardforthelefthand,loopsflowingtowardthethumbimpressionareulnar,andloopsflowingtowardthelittlefingerimpressionareradial.[Pg32]

Theplainarch

Inplainarchestheridgesenterononesideoftheimpressionandflowortendtoflowouttheotherwithariseorwaveinthecenter.Theplainarchisthemostsimpleofallfingerprintpatterns,anditiseasilydistinguished.Figures107to118areexamplesoftheplainarch.Itwillbenotedthattheremaybevariousridgeformationssuchasendingridges,bifurcations,dotsandislandsinvolvedinthistypeofpattern,buttheyalltendtofollowthegeneralridgecontouri.e.,theyenterononeside,makeariseorwaveinthecenter,andflowortendtoflowouttheotherside.



[Pg33]

[Pg34]



[Figs.107118]

Figures119and120areexamplesofplainarcheswhichapproximatetentedarches.Also,figure121isaplainarchapproximatingatentedarchastherisingridgecannotbeconsideredanupthrustbecauseitisacontinuous,andnotanending,ridge.(Seefollowingexplanationofthetentedarch.)

[Figs.119121]

[Pg35]

Thetentedarch

Inthetentedarch,mostoftheridgesenterupononesideoftheimpressionandflowortendtoflowoutupontheotherside,asintheplainarchtypehowever,theridgeorridgesatthecenterdonot.Therearethreetypesoftentedarches:

Thetypeinwhichridgesatthecenterformadefiniteanglei.e.,90orless.

Thetypeinwhichoneormoreridgesatthecenterformanupthrust.Anupthrustisanendingridgeofanylengthrisingatasufficientdegreefromthehorizontalplanei.e.,45ormore.

Thetypeapproachingthelooptype,possessingtwoofthebasicoressentialcharacteristicsoftheloop,butlackingthethird.

Figures122to133areexamplesofthetentedarch.



[Pg36]

[Pg37]



[Figs.122133]

Figures122to124areofthetypepossessinganangle.

Figures125to129reflectthetypepossessinganupthrust.

Figures130to133showthetypeapproachingtheloopbutlackingonecharacteristic.

Tentedarchesandsomeformsoftheloopareoftenconfused.Itshouldberememberedbythereaderthatthemereconvergingoftworidgesdoesnotformarecurve,withoutwhichtherecanbenoloop.Ontheotherhand,therearemanypatternswhichatfirstsightresembletentedarchesbutwhichoncloseinspectionarefoundtobeloops,aswhereoneloopingridgewillbefoundinanalmostverticalpositionwithinthepatternarea,entirelyfreefromandpassinginfrontofthedelta.

Figure134isatentedarch.Theridgemarked"AA"inthesketchentersononesideoftheimpressionandflowstotheotherwithanacuteriseinthecenter.RidgeCstrikesintoAatpointBandshouldnotbeconsideredasabifurcatingridge.Theridgesmarked"DD"wouldformatentedarchiftherestofthepatternwereabsent.

[Fig.134]

[Pg38]

Figure135isasketchofapatternreflectingaridge,AB,enteringononesideoftheimpression,recurving,andmakingitsexitontheothersideoftheimpression.Thereadershouldstudythissketchcarefully.Itshouldbeborneinmindthattheremustbearidgeenteringononesideoftheimpressionandrecurvinginordertomakeitsexitonthesamesidefromwhichitentered,orhavingatendencytomakeitsexitonthatside,beforeapatterncanbeconsideredforpossibleclassificationasaloop.Thispatternisatentedarchoftheupthrusttype.TheupthrustisC.ThereisalsoanangleatE.Dcannotbetermedasadelta,astheridgetotheleftofDcannotbeconsideredatypelinebecauseitdoesnotdivergefromtheridgetotherightofDbutturnsandgoesinthesamedirection.

[Fig.135]



Inconnectionwiththetypesoftentedarches,thereaderisreferredtothethirdtype.Thisformoftentedarch,theonewhichapproachestheloop,mayhaveanycombinationoftwoofthethreebasicloopcharacteristics,lackingthethird.Thesethreeloopcharacteristicsare,torepeat:

Asufficientrecurve.

Adelta.

Aridgecountacrossaloopingridge.

Itmustberememberedthatarecurvemustbefreeofanyappendageabuttinguponitatarightanglebetweentheshoulders,andatrueridgecountisobtainedonlybycrossingaloopingridgefreely,withawhitespaceinterveningbetweenthedeltaandtheridgetobecounted.

Figures136and137aretentedarcheshavingloopformationswithinthepatternareabutwithdeltasupontheloops,byreasonofwhichitisimpossibletosecurearidgecount.Thetypelinesrunparallelfromtheleftinfigures136and137.Thesetentedarcheshavetwooftheloopcharacteristics,recurveanddelta,butlackthethird,theridgecount.[Pg39]

[Figs.136137]

Infigure138,thereaderwillnotethesimilaritytothefigures136and137.Theonlydifferenceisthatinthisfigurethetypelinesarerunningparallelfromtheright.Itwillbenotedfromthesethreepatternsthatthespacesbetweenthetypelinesattheirdivergenceshownothingwhichcouldbeconsideredasdeltaformationsexcepttheloopingridges.Suchpatternsareclassifiedastentedarchesbecausetheridgecountnecessaryforaloopislacking.

[Fig.138]

Figure139isanexampleofatentedarch.Inthispattern,iftheloopingridgeapproachedtheverticalitcouldpossiblybeaonecountloop.Oncestudied,however,thepatternpresentsnorealdifficulty.Therearenoridgesinterveningbetweenthedelta,whichisformedbyabifurcation,andthecore.Itwillbenotedthatthecore,inthiscase,isatthecenter[Pg40]oftherecurve,unlikethoseloopswhicharebroadsidetothedeltaandinwhichthecoreisplacedupontheshoulder.Thispatternhasarecurveandaseparatedelta,butitstilllackstheridgecountnecessarytomakeitaloop.



[Fig.139]

Figures140and141areexamplesoftentedarches.Thesetwofiguresaresimilarinmanyways.Eachoftheseprintshasthreeabruptendingridgesbutlacksarecurvehowever,infigure141adeltaispresentinadditiontothethreeabruptendingridges.Thisconditiondoesnotexistinfigure140,wherethelowerendingridgeisthedelta.

[Figs.140141]

Wheninterpretingapatternconsistingoftwoendingridgesandadeltabutlackingarecurve,donotconfusetheridgecountofthetentedarchwiththatoftheridgecountfortheloop.Theridgecountofthetentedarchismerelyaconventionoffingerprinting,afictiondesignedtofacilitateascientificclassificationoftentedarches,andhasnoconnectionwithaloop.Toobtainatrueridgecounttheremustbealoopingridgewhichiscrossedfreelybyanimaginarylinedrawnbetweenthedeltaandthecore.Theridgecountreferredtoassuchinconnectionwiththetentedarchespossessingendingridgesandnorecurveisobtainedbyimaginingthattheendingridgesarejoinedbyarecurveonlyforthepurposeoflocatingthecoreandobtainingaridgecount.Ifthispointissecureinthemindoftheclassifier,littledifficultywillbeencountered.

Figures140and141,then,aretentedarchesbecausetheyhavetwoofthecharacteristicsofaloop,deltaandridgecount,butlackthethird,therecurve.

Figure142isaloopformationconnectedwiththedeltabuthavingnoridgecountacrossaloopingridge.Bydrawinganimaginarylinefromthecore,whichisatthetopoftherodinthecenterofthepattern,tothedelta,itwillbenotedthatthereisnorecurvingridgepassingbetweenthisrodandthedeltaand,therefore,noridgecountcanresult.Thispatternisclassifiedasatentedarch.Theremustbeawhitespacebetweenthedeltaandthefirstridgecounted,oritmaynotbecounted.Figure143isalsoatentedarchbecausenoridgecountacrossaloopingridgecanbeobtained,thebifurcationsbeingconnectedtoeachotherand[Pg41]totheloopinastraightlinebetweendeltaandcore.Theloopingridgeisnotcrossedfreely.Nowhitespaceintervenesbetweenthedeltaandtheloop.Thesepatternsaretentedarchesbecausetheypossesstwoofthecharacteristicsofaloop,adeltaandarecurve,butlackthethird,aridgecountacrossaloopingridge.



[Figs.142143]

Figure144isatentedarchcombiningtwoofthetypes.Thereisanangleformedbyridgeaabuttinguponridgeb.Therearealsotheelementsofthetypeapproachingaloop,asithasadeltaandridgecountbutlacksarecurve.

[Fig.144]

Figures145to148aretentedarchesbecauseoftheanglesformedbytheabuttingridgesatthecenterofthepatterns.

[Figs.145148]

Figure149isatentedarchbecauseoftheupthrustpresentatthecenterofthepattern.Thepresenceoftheslightestupthrustatthecenteroftheimpressionisenoughtomakeapatternatentedarch.[Pg42]



[Fig.149]

Anupthrustmustbeanendingridge.Ifcontinuousasinfigure150,noanglebeingpresent,thepatternisclassifiedasaplainarch.

[Fig.150]

Figures151to153areplainarches.Figure154isatentedarch.

[Figs.151154]

Figure155isaplainarchbecauseitisreadilyseenthattheapparentupthrustAisacontinuationofthecurvingridgeB.Figure156isatentedarchbecauseridgeAisanindependentupthrust,andnotacontinuationofridgeB.



[Figs.155156]

[Pg43]

Figures157and158areplainarches.Figure158cannotbesaidtobealoopingridge,becausebydefinitionaloopmustpassoutortendtopassoutuponthesidefromwhichitentered.Thisapparentlooppassesoutupontheoppositesideandcannotbesaidtotendtoflowoutuponthesameside.

[Figs.157158]

Infigures159and160,thereareendingridgesrisingataboutthesamedegreefromthehorizontalplane.

[Figs.159160]

Figure159,however,isaplainarch,while160isatentedarch.Thisdifferentiationisnecessarybecause,ifthefirstpatternwereprintedcrookedlyuponthefingerprintcardsothattheendingridgewasnearerthehorizontalplane,therewouldbenowaytoascertainthetruehorizontalplaneofthepattern(ifthefissureofthefingerdidnotappear).Inotherwords,therewouldbenomeansofknowingthattherewassufficientrisetobecalledanupthrust,sothatitissafetoclassifytheprintasaplainarchonly.Infigure160,however,nomatterhowitisprinted,thepresence[Pg44]ofasufficientrisecouldalwaysbeascertainedbecauseofthespaceinterveningbetweentheendingridgeandtheridgeimmediatelybeneathit,sothatitissafetoclassifysuchapatternasatentedarch.Thetestis,iftheridgesonbothsidesoftheendingridgefollowitsdirectionorflowtrend,theprintmaybeclassifiedasaplainarch.If,however,theridgesononlyonesidefollowitsdirection,theprintisatentedarch.

Anupthrust,then,mustnotonlybeanendingridgerisingatasufficientdegreefromthehorizontalplane,buttheremustalsobeaspacebetweentheendingridgeandtheridgeimmediatelybeneathit.This,however,isnotnecessaryforashortupthrustorspike,oranyupthrustwhichrisesperpendicularly.

Inconnectionwiththeproperclassificationtobeassignedtothoseborderlinelooptentedarchcaseswhereanappendageorspikeisthrustingoutfromtherecurve,itisnecessarytorememberthatanappendageoraspikeabuttinguponarecurveatrightanglesinthespacebetweentheshouldersofaloopontheoutsideisconsideredtospoiltherecurve.

Iftheappendingridgeflowsofftheloopingridgesmoothlyinsuchawaythatitformsabifurcationandnotanabutmentoftworidgesatarightangle,therecurveisconsideredasremainingintact.Thetestistotracetheloopingridgetowardtheappendage,andif,whenitisreached,thetracingmaybecontinuedasreadilyupontheappendageasupontheloopingridge,withnosudden,sharpchangeofdirection,the



recurveissufficient.Figures161to184shouldbestudiedwiththisinmind.

[Pg45]

[Pg46]



[Figs.161184]

[Pg47]

Figures185to190showadditionalexamplesoftentedarches.



[Figs.185190]

Thereasonthatfigure185isgiventheclassificationofatentedarchisbecauseofthepresenceofallthelooprequirementswiththeexceptionofone,whichistherecurve.Inthispatternappearthreeendingridges.[Pg48]Thelowestendingridgeprovidesthedelta,andtheothertwobytheconventionexplainedpreviously,providetheridgecount.Itisatentedarch,then,ofthetypeapproachingtheloop,withtwoofthecharacteristics,butlackingthethird,arecurve.Figures186and187aretentedarchesofthesametype.Acloseexaminationoftheseprintswillrevealthatwhentheimaginarylineisdrawnbetweendeltaandcorenoridgecountacrossaloopingridgecanbeobtained.Itmustberememberedthatthecoreofaloopmaynotbeplacedbelowtheshoulderline.Lackingoneofthethreecharacteristicsofaloop,thesepatternsmustbeclassifiedastentedarches.Whenfigure188isexamined,itwillbenoticedthattherecurveisspoiledbytheappendageabuttinguponitbetweentheshouldersatarightangle,soitmustalsobeclassifiedwiththetentedarches.Infigure189,theonlypossibledeltamustbeplacedupontheloopingridge,thuspreventingaridgecountalthoughdeltaandrecurvearepresent.Figure190isassignedtheclassificationofatentedarch.Oneoftherequirementsofalooptypeisthattheridgeentersononeside,recurves,andmakesitsexitonthesidefromwhichitentered.This,ofcourse,makesitnecessary[Pg49]thattheridgepassbetweenthedeltaandthecore.Itwillbenotedfromthisfigurethatalthoughthisridgepassesbetweenthedeltaandthecore,itdoesnotshowanytendencytomakeitsexitonthesidefromwhichitentered,andthereforetheloopclassificationisprecluded,anditisatentedarch.

Thewhorl

Thepatternstowhichnumericalvaluesareassignedinderivingthe"primary"intheextensionoftheHenrySystemoffingerprintclassificationusedbytheFederalBureauofInvestigationarethewhorltypepatterns,whichoccurinabout30percentofallfingerprints.

Thewhorlisthattypeofpatterninwhichatleasttwodeltasarepresentwitharecurveinfrontineach.Figures191to193reflecttheminimumrequirementsforthewhorl.



[Figs.191193]

Itisimportanttonotethattheabovedefinitionisverygeneralhowever,thispatternmaybesubdividedforextensionpurposesinlargegroupswherewhorlsarepredominant.Eventhoughthisextensionmaybeused,alltypesofwhorlsaregroupedtogetherunderthegeneralclassificationof"Whorl"andaredesignatedbytheletter"W".

Theaforementionedsubdivisionsareasfollows:ThePlainWhorl,TheCentralPocketLoop,TheDoubleLoop,andTheAccidental.

Theplainwhorl

The"plainwhorl"consistsofthesimplestformofwhorlconstructionandisthemostcommonofthewhorlsubdivisions.Itisdesignatedbythesymbol"W"forbothgeneralclassificationandextensionpurposes.

Theplainwhorlhastwodeltasandatleastoneridgemakingacompletecircuit,whichmaybespiral,oval,circular,oranyvariantofacircle.Animaginarylinedrawnbetweenthetwodeltasmusttouchorcrossatleastoneoftherecurvingridgeswithintheinnerpatternarea.Arecurvingridge,however,whichhasanappendageconnectedwithitin[Pg50]thelineofflowcannotbeconstruedasacircuit.Anappendageconnectedatthatpointisconsideredtospoiltherecurveonthatside.

Figures194to211aretypicalexamplesoftheplainwhorltype.Figure212is,however,aloop,asthecircuitisspoiledononesidebyanappendage.

[Pg51]



[Pg52]



[Figs.194212]

[Pg53]

Centralpocketloop

Withinthewhorlgroup,thesubclassificationtype"centralpocketloop"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W".Figures213to236arecentralpocketloops.



[Figs.213236]

Thecentralpocketlooptypeofwhorlhastwodeltasandatleastoneridgemakingacompletecircuit,whichmaybespiral,oval,circular,oranyvariantofacircle.Animaginarylinedrawnbetweenthetwodeltasmustnottouchorcrossanyoftherecurvingridgeswithintheinnerpatternarea.Arecurvingridge,however,whichhasanappendageconnectedwithitinthelineofflowandonthedeltasidecannotbeconstruedasacircuit.Anappendageconnectedatthatpointisconsideredtospoiltherecurveonthatside.

Inlieuofarecurveinfrontofthedeltaintheinnerpatternarea,anobstructionatrightanglestothelineofflowwillsuffice.

Itisnecessarythattheinnerlineofflowbefixedartificially.Theinnerlineofflowisdeterminedbydrawinganimaginarylinebetweentheinnerdeltaandthecenteroftheinnermostrecurveorloopingridge.

Inthecentralpocketloop,oneormoreofthesimplerecurvesoftheplainlooptypeusuallyrecurveasecondtimetoformapocketwithintheloop.Thesecondrecurve,however,neednotbeacontinuationoforevenconnectedwiththefirst.Itmaybeanindependentridge.

Ifnosecondrecurveispresent,anobstructionatrightanglestotheinnerlineofflowisacceptableinlieuofit.Anobstructionmaybeeithercurvedorstraight.Adot,ofcourse,maynotbeconsideredanobstruction.

Thedefinitiondoesnotrequirearecurvetocrossthelineofflowatrightangles.Theangletestneedstobeappliedtoobstructionsonly.

Therecurveorobstructionofthecentralpocketloop,asthatoftheplainwhorl,mustbefreeofanyappendageconnectedtoitatthepointcrossedbythelineofflowandonthedeltaside.Anappendageatthatpointisconsideredtospoiltherecurveorobstruction.

[Pg58]

Figures237and238arealsocentralpocketloopsdespitetheappendagesconnectedtotherecurves,



becausetheyarenotconnectedatthepointcrossedbythelineofflow.

[Figs.237238]

Figure239,althoughpossessingarecurve,isclassifiedasaloopbecausetheseconddeltaislocatedontheonlyrecurvingridge.

[Fig.239]

[Pg59]

Figures240to244,althoughpossessingonedeltaandadeltaformation,areclassifiedasloopsbecausetheobstructionsdonotcrossthelineofflowatrightangles.



[Figs.240244]

[Pg60]

Figures245to254havetwodeltasandoneormorerecurves,buttheyareclassifiedasloopsbecauseeachrecurveisspoiledbyanappendageconnectedtoitatthepointcrossedbythelineofflow.



[Figs.245254]

[Pg61]

Doubleloop

Withinthewhorlgroup,thesubclassificationtype"doubleloop"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W".

Thedoubleloopconsistsoftwoseparateloopformations,withtwoseparateanddistinctsetsofshoulders,andtwodeltas.

Theword"separate,"asusedhere,doesnotmeanunconnected.Thetwoloopsmaybeconnectedbyanappendingridgeprovidedthatitdoesnotabutatrightanglesbetweentheshouldersoftheloopformation.Theappendagerulefortheloopappliesalsotothedoubleloop.Anappendageabuttinguponaloopatrightanglesbetweentheshouldersisconsideredtospoiltheloop,whileanappendagewhichflowsoffsmoothlyisconsideredtoleavetherecurveintact.

Thefactthattheremustbetwoseparateloopformationseliminatesfromconsiderationasadoubleloopthe"S"typecore,theinterlockingtypecore,andtheformationwithoneloopinsideanother.

Theloopsofadoubleloopdonothavetoconformtotherequirementsoftheloop.Inotherwords,noridgecountisnecessary.

Itisnotessentialthatbothsidesofaloopbeofequallength,northatthetwoloopsbeofthesamesize.Neitherisitmaterialfromwhichsidetheloopsenter.

ThedistinctionbetweentwinnedloopsandlateralpocketloopsmadebyHenryandadoptedbyotherauthorshasbeenabandonedbytheFederalBureauofInvestigationbecauseofthedifficultyinlocatingandtracingtheloops.Bothtypeshavebeenconsolidatedundertheclassification"doubleloop."

Figures255to266aredoubleloops.



[Pg62]



[Figs.255266]

[Pg63]

Figure267isaplainwhorl.Itisnotclassifiedasadoubleloopasonesideofoneloopformsthesideoftheother.Figure268isaplainloop.Itisnotadoubleloopbecausealloftherecurvesoftheloopontherightarespoiledbyappendages.

[Figs.267268]

[Pg64]

Accidental

Withinthewhorlgroupthesubdivisiontype"accidental"isusedforextensionpurposesonly.Ingeneralclassificationitisdesignatedbytheletter"W"andforextensionpurposesbytheletter"X".

Theaccidentalwhorlisapatternconsistingofacombinationoftwodifferenttypesofpattern,withtheexceptionoftheplainarch,withtwoormoredeltasorapatternwhichpossessessomeoftherequirementsfortwoormoredifferenttypesorapatternwhichconformstononeofthedefinitions.Itmaybeacombinationofloopandtentedarch,loopandwhorl,loopandcentralpocketloop,doubleloopandcentralpocketloop,orothersuchcombinations.Theplainarchisexcludedasitisrathertheabsenceofpatternthanapattern.Underneatheverypatternthereareridgesrunningfromonesidetotheother,sothatifitwerenotexcludedeverypatternbuttheplainarchwouldbeanaccidentalwhorl.

Thissubclassificationalsoincludesthoseexceedinglyunusualpatternswhichmaynotbeplacedbydefinitionintoanyotherclasses.

Figures269to271areaccidentalscombiningaloopwithatentedarch.[Pg66]Figures272to276combinealoopandaplainwhorlorcentralpocketloop.Figure277combinesaloopandadoubleloop.Figure278combinesaloopandaplainarch,soitisclassifiedasaloop.Figure279combinesaloopandatentedarch.



[Figs.269279]

Somewhorlsmaybefoundwhichcontainridgesconformingtomorethanoneofthewhorlsubdivisionsdescribed.Insuchcases,theorderofpreference(ifanypracticaldistinctionneedbemade)shouldbe:(1)accidental,(2)doubleloop,(3)centralpocketloop,(4)plainwhorl.

Whorltracing

Thetechniqueofwhorltracingdependsupontheestablishmentofthefocalpointsthedeltas.Everywhorlhastwoormore.Whenthedeltashavebeenlocated,theridgeemanatingfromthelowersideorpointoftheextremeleftdeltaistraceduntilthepointnearestoroppositetheextremerightdeltaisreached.Thenumberofridgesinterveningbetweenthetracingridgeandtherightdeltaarethencounted.Iftheridgetracedpassesinsideof(above)therightdelta,andthreeormoreridgesintervenebetweenthetracingridgeandthedelta,thetracingisdesignatedasan"inner"I(fig.280).Iftheridgetracedpassesoutside(below)the[Pg67]rightdelta,andthreeormoreridgesintervenebetweenthetracingridgeandtherightdelta,thetracingisdesignatedasan"outer"O(fig.281).Allothertracingsaredesignatedas"meeting"M(figs.282to287).



[Figs.280287]

[Pg68]

Tracingbeginsfromtheleftdelta.Innoinstanceisatracingtobeginonatypeline.Infigure288,tracingbeginsattheshortridgewhichistheleftdelta.Itistruethatinasmuchastheshortridgeendsimmediatelythetypelineisnextfollowed,butthisisonlybecausethetypelineisthenextlowerridge.Itsstatusasatypelineisindependentandhasnobearingonthefactthatitisbeingtraced.Thispointisillustratedfurtherinfigure289.Thispatternshowsaninnertracing.Itwillbenotedthatthedeltaisatthepointonthefirstrecurvenearesttothecenterofthedivergenceofthetypelines.Itwillbefurthernotedthattracingbeginsatthepointofdeltaontheleftandcontinuestowardtheright,passinginsideoftherightdelta,withthreeridgesinterveningbetweenthetracingridgeandtherightdelta.Thisshowsthetracingtobeaninnertracing.If,inthiscase,thetypelineweretraced(whichwouldbetheincorrectprocedure),onlytworidgeswouldintervenebetweenthetracingridgeandtherightdelta,resultinginanerroneousmeetingtracing.Figure290isanotherexampleoftheapplicationofthisrule.Thisillustrationisalsoaninnerwhorl.



[Figs.288290]

Whentheridgetracedendsabruptly,anditisdeterminedthattheridgedefinitelyends,thetracingdropsdowntothepointonthenextlowerridgeimmediatelybeneaththepointwheretheridgeaboveends,continuingfromthere.Figure291,therefore,isanouterwhorl.

[Fig.291]

Inthisconnectionitshouldbenotedthattherulefordroppingtothenextlowerlineappliesonlywhentheridgedefinitelyends.Shortbreaksinaridgewhichmaybeduetoimproperinking,thepresenceofforeignmatterontheridges,enlargedpores,disease,orwornridgesshouldnotbeconsideredasdefiniteridgeendings.Thedeterminationofwhatconstitutesadefiniteendingwilldepend,ofcourse,uponthegoodjudgmentoftheclassifier.Whenthequestionarisesastowhetherabreakencoun[Pg69]teredintheridgetracingisadefiniteending,orwhethertherehasbeeninterferencewithanaturalimpression,thewholepatternshouldbeexaminedtoascertainwhethersuchbreaksaregeneralthroughoutthepattern.Iftheyarefoundtobecommon,considerationshouldthenbegiventothepossibilitythatthebreakisnotadefiniteridgeending.Appropriatereferencetracingshouldbedoneinallsuchcases.

Whenevertheridgetracedbifurcates,therulefortracingrequiresthatthelowerlimborbranchproceedingfromthebifurcationbefollowed.Thisisillustratedin292.

[Fig.292]

Accidentalsoftenpossessthreeormoredeltas.Intracingthemonlytheextremedeltasareconsidered,thetracingbeginningattheextremeleftdeltaandproceedingtowardtheextremerightdelta,asillustratedinfigure293.[Pg70]



[Fig.293]

Inadoublelooporaccidentaltheproblemofwheretostoptracingissometimespresented.Theruleis,whenthetracingpassesinsideoftherightdelta,stopatthenearestpointtotherightdeltaontheupwardtrend,asinfigure294.Ifnoupwardtrendispresent,continuetracinguntilapointoppositetherightdelta,orthedeltaitself,isreached(figs.295and296).

[Figs.294296]

[Pg71]

CHAPTERIII

QuestionablePatterns

Nomatterhowdefinitefingerprintrulesandpatterndefinitionsaremade,therewillalwaysbepatternsconcerningwhichthereisdoubtastotheclassificationtheyshouldbegiven.Theprimaryreasonforthisisthefactthatprobablynotwofingerprintswilleverappearwhichareexactlyalike.Otherreasonsaredifferencesinthedegreeofjudgmentandinterpretationoftheindividualclassifyingfingerprints,thedifferenceintheamountofpressureusedbythepersontakingtheprints,andtheamountorkindofinkused.Nothingcanbedoneaboutfaultyinkingorpressureoncetheprintsaretaken.Thepatternswhicharequestionablemerelybecausetheyseemtohavecharacteristicsoftwoormoretypescanbeclassifiedbystrictadherencetothedefinitionsindeducingapreference.Thefollowingsectionisdevotedtosuchpatternswithanexplanationofeach.

Figure297hastwoloopformations.Theoneontheleft,however,hasanappendageabuttingupontheshouldersofitsrecurveatarightangle.Theleftportionoftheimpression,therefore,isofthetentedarchtype.Thecombinationoftwodifferenttypesofpatternswouldbeclassifiedinthewhorlgroup(accidental),butthisimpressionhasonlytheonedelta.Therightportionofthepatterndetailcontainsatrueloopwhichfulfillsallthelooprequirements,i.e.,asufficientrecurve,adelta,andaridgecountacrossaloopingridge.Inthechoiceexistingbetweenatentedarchandaloop,preferenceisgiventotheloopclassificationandthisimpressionwouldbeclassifiedasaloop.[Pg72]



[Fig.297]

Figure298,ataglance,seemstofulfilltherequirementsofawhorl(twodeltasandaridgemakingacompletecircuit).Thepartofthecircuitinfrontoftherightdelta,however,cannotbeconstruedasarecurvingridgebecauseoftheappendageabuttinguponitinthelineofflow.Thispattern,therefore,isaonecountloop.

[Fig.298]

Figure299isaverydifficultandunusualpattern.Ithascharacteristicsofthreetypes,thewhorl,theloop,andthetentedarch.Itisgiventhepreferenceofanaccidentaltypeofwhorl(loopoveratentedarch).Thispatternshouldbereferencedbothasaloopandasatentedarch.

[Fig.299]

Figure300isshownforthepurposeofexplainingthatinthewhorl,asthisprintis,appendagesatthetopoftherecurvewillnotspoiloraffecttherecurve.Hence,theimpressionisagoodwhorlofthecentralpocketlooptypeandneedsnoreference.



[Fig.300]

Figure301isclassifiedasawhorlofthedoublelooptype.Therearepresenttwodistinctloopsandtwodeltas(therightdeltaisnotpresentastheimpressionwasnotrolledsufficiently).Thepatternisunusualbecausetheloopsaresidebysideandflowinginthesamedirection.Thetracingisaninnertracing.[Pg73]

[Fig.301]

Figure302shouldpresentnodifficulty.Itisclassifiedasaplainarchforitsridgeconstructionfollowstheruleofaplainarch,i.e.,"enteronesideandflowortendtoflowtotheother."

[Fig.302]

Figure303isaplainarch.Thedotatthecenterisnotelongatedenoughtobeconsideredanupthrust.Adot,eventhoughasthickandheavyasthesurroundingridges,isnotconsideredforanypurposebutridgecountingorfixingadelta.



[Fig.303]

Figure304isapatternsomewhatsimilartothepreviousillustration.Asindicatedbefore,dotsareconsideredasridgesonlyinridgecountingandfixingadelta.Thispattern,therefore,mustbeclassifiedasaplainarch,ratherthanatentedarchwithtwoendingridgesandadeltaformation.

[Fig.304]

Figure305,althoughshowinganappendageuponeachrecurveontheleftside,isclassifiedasawhorlofthecentralpocketlooptype,withtwodeltasandarecurveinfrontofeach.Tospoiltherecurveofawhorltheappendagemustbeconnectedtotherecurveatthepointofcontactwiththelineofflow.

[Fig.305]

[Pg74]Infigure306,theimpressionhastwoequallygoodloopformations.Asithasbutonedelta,itcannotbeclassifiedasawhorlofthedoublelooptypenorasaloopsinceitwouldbedifficulttomakeapreferentialchoicebetweenthetwoloopingridges.Itisarbitrarilygiventheclassificationofatentedarch.



[Fig.306]

Infigure307,thedifficultyliesinlocatingthedelta.Theonlyridgesansweringthedefinitionoftypelines(ridgesrunningparallelandthendivergingtoenclosethepatternarea)havethreeendingridgesbetweenthem.Thetypelines,thedelta,andthecorearelocatedasindicated.Thepatternisclassifiedasasixcountloop.

[Fig.307]

Figure308isclassifiedasatentedarch,althoughitappearsatfirstglancetobealoop.Closerinspectionshowsthattheloopingridgedoesnottendtogooutthesidefromwhichitenteredbutratherseemstoproceeddownwardendinginanabutmentformingadefiniteangleof90.

[Fig.308]

[Pg75]

Infigure309,animpressionisshownwhichatfirstappearstobealoop.Closerinspectionwillshowthatoneoftheelementsofthelooptypeismissing,namely,aridgecountacrossaloopingridgeforitistobeborneinmindthattherecurveoftheinnermostloopshouldbefreeofappendagesabuttingbetweentheshouldersatrightangles.Thecore,inthisillustration,therefore,isplacedwheretheappendageoftheinnermostlooptouchesthenextridgewhichisagoodrecurve.Ifanimaginarylineisplacedbetweendeltaandcore,itwillbeseenthattherearenointerveningridgeshence,thereisnoridgecount.



[Fig.309]

Figure310isapatternwhichcontainstwoelementsofaloopbutlacksthethird.Itisclassifiedasatentedarch.Thusanimpressionhavingadeltaandarecurve,butnothavingaridgecountacrossaloopingridge,fallsintothisclassification.

[Fig.310]

Itwillbenoticedthatalthoughthispatternhastheresemblanceofaplainarch,thecenteroftheimpressionactuallycontainsapartiallyformedloop.Arecurvingridgeentersfromtherightsideandexitsinthesamedirection.Adeltaalsoappearsjustbelowtherecurve.Inattempting[Pg76]toobtainaridgecount,itisseenthattheimaginarylinedrawnbetweenthedeltaandthecorerunsdirectlyalongtheridgeemanatingfromtheformerandwhichisjoinedontothesideoftherecurvingridge.Forthisreason,noridgecountispossible.

Figure311isatentedarch.Therearethreeloopformations,eachoneofwhichisspoiledbyanappendageabuttinguponitsrecurvebetweentheshouldersatarightangle.Itcannotbeclassifiedasanaccidentalasthepatternsareallofthesametype,i.e.,tentedarches.Anaccidentaltypeofwhorlisacombinationoftwoormoredifferenttypesofpatternsexclusiveoftheplainarch.

[Fig.311]

Figure312isaloop.Itcannotbeclassifiedasawhorlofthedoublelooptypebecausetheformationabovethelowerloopistoopointedanditalsohasanappendageabuttinguponitatarightangle.



[Fig.312]

Figure313atfirstglanceappearstobeawhorlofthedoublelooptype.Uponcloserinspection,however,itwillbenoticedthattherearenodeltaformationsotherthanontherecurves.Thereare,then,twotentedarchformations.Astwopatternsofthesametypecannotformanaccidentalwhorl,theimpressionmustbeclassifiedasatentedarch.[Pg77]

[Fig.313]

Figure314isanaccidentalwhorl,combiningaloopandatentedarch.Thetentedarchisdirectlybeneaththeinnermostloop,andisoftheupthrusttype.

[Fig.314]

Figure315consistsofaloopoveradotwithanapparentseconddelta.Thispatternmustbeclassifiedasaloop,asadotmaynotbeconsideredanupthrustunlesselongatedvertically.



[Fig.315]

Eventhoughadotmaybeasthickandheavyasthesurroundingridges,itmaybeconsideredonlyinridgecountingorfixingadelta.

Figure316atfirstglanceappearstobeanaccidentalwhorl,butoncloserinspectionitprovestobealoop.Althoughtherearethreedeltaformationspresent,itshouldbeobservedthatrecurvingridgesappearinfrontofonlyone(D1).

[Fig.316]

Figure317hasthegeneralappearanceofaloop.TheloopingridgeA,atthecenter,hasanappendageBabuttinguponitsrecurve.Theabutmentisatrightanglesandthereforespoilstherecurve.Thepatternisatentedarch.[Pg78]

[Fig.317]

Figure318isatentedarchwhichapproachesboththeloopandthewhorltypepatterns.Itcannotbeconsideredawhorl,however,astherecurveontheleftisspoiledbyanappendage(figs.58and59).Norcanitbealoopbecausethereisnoridgecountacrossaloopingridge.Thepattern,then,isatentedarchofthetypepossessingtwoofthebasiccharacteristicsoftheloopandlackingthethird.Thedeltaandthesufficientrecurvearepresentbuttheridgecountismissing.



[Fig.318]

Figure319seemsatfirstglancetobeadoubleloop.Itwillbenoted,however,thattheinnerdeltaformationwouldbelocatedupontheonlyloopingridgeoftheupperloopformation.Sincethedeltawouldbelocatedontheonlyrecurve,thisrecurvingridgeiseliminatedfromconsideration.Thepatternisclassifiedasaloop.

[Fig.319]

Figure320isaloopoftwocounts,withthedeltaatB.Thereisaridgemakingacompletecircuitpresent,butpointAcannotbeusedasadeltabecauseitanswersthedefinitionofatypeline.Itshouldbeconsideredadeltaonlyifitpresentedanangularformation.Placingthedeltaupontherecurvewouldspoilthatrecurve.

[Fig.320]

Figure321showstwoseparateloopingridgeformationsappearingsidebysideanduponthesamesideofthedelta.Thecoreinsuchcaseisplaceduponthenearershoulderofthefartherloopingridgefromthedelta,thetwoloopingridgesbeingconsideredasoneloopwithtworodsrisingashighastheshoulder.Theridgecountwouldbefour(fig.49).



[Fig.321]

Figure322isanaccidentalwhorl.Itisclassifiedthusbecauseitcontainselementsofthreedifferentpatterns,theloop,thedoubleloop,andtheaccidental.Insuchcasetheorderofpreferencegoverns.ThedeltaattheleftispointA.ThedeltaattherightispointC.Thispointbecomesthedeltasinceitisthepointnearestthecenterofthedivergenceofthetypelines.PointBiseliminatedfromconsiderationasadeltasincetypelinesmaynotproceedfromabifurcationunlesstheyflowparallelafterthebifurcationandbeforediverging.[Pg79]

[Fig.322]

[Pg80]

Figure323isaloop.Therearetwodeltaformationsbutthedotscannotbeconsideredasobstructionscrossingthelineofflowatrightangles.Thisprecludestheclassificationofthecentralpocketlooptypeofwhorl.

[Fig.323]

Figure324isaloop,thetworecurvingridgeshaveappendagesandareconsideredspoiled.Thepatterncannot,therefore,beawhorleventhoughtwodeltaformationsarepresent.



[Fig.324]

Figure325isclassifiedasatentedarch.Ifexaminedcloselythepatternwillbeseentohaveanappendageabuttingatarightanglebetweentheshouldersofeachpossiblerecurve.Thusnosufficientrecurveispresent.

[Fig.325]

Figure326isaplainarch.Thereispresentnoanglewhichapproachesarightangle.PointsA,B,andXaremerelybifurcationsratherthananabutmentoftworidgesatanangle.

[Fig.326]

Figure327isatentedarch,notbecauseofthedot,however,asitcannotbeconsideredanupthrust.Thetentedarchisformedbytheanglemadewhenthecurvingridgeabovethedotabutsupontheridgeimmediatelyunderandtotheleftofthedot.[Pg81]



[Fig.327]

Figure328consistsoftwoseparateloopingridgeformationsinjuxtapositionuponthesamesideofacommondelta.Thispatterncannotbecalledadoubleloopasthereisnoseconddeltaformation.Inordertolocatethecore,thetwoloopingridgesshouldbetreatedasoneloopwithtworodsinthecenter.Thecoreisthusplacedonthefarrod(actuallyontheleftshoulderofthefarloop),resultinginaridgecountoffour(fig.49).

[Fig.328]

Figure329isaloopofthreecounts.Itcannotbeclassifiedasawhorlastheonlyrecurveisspoiledbytheappendageabuttinguponitatthepointofcontactwiththelineofflow.

[Fig.329]

Figure330isaplainarchasthereisnoupthrust(anupthrustmustbeanendingridge),nobackwardloopingturn,andnotworidgesabuttinguponeachotheratasufficientangle.



[Fig.330]

Figure331isaplainarch.Theendingridgeatthecenterdoesnotriseatasufficientangletobeconsideredanupthrust,anditdoesnotquitemeettheridgetowardwhichitisflowingandthereforeformsnoangle.[Pg82]

[Fig.331]

Figure332isaplainarch.Therearetwoendingridges,butnoseparatedeltaformationispresent.

[Fig.332]

Figure333isaplainarch.Therisingridgeatthecenteriscurvedatthetopformingnoangle,anddoesnotconstituteanupthrustbecauseitisnotanendingridge.



[Fig.333]

Figure334isawhorlofthedoublelooptype.Twoloopsandtwodeltasarepresent.Itisunusualbecausetheloopsarejuxtaposedinsteadofoneflowingovertheother,andonedeltaisalmostdirectlyovertheother.Thetracingisameetingtracing.

[Fig.334]

Figure335isatentedarch.Althoughthereisaloopingridge,noridgecountcanbeobtained.Thecoreisplacedupontheendoftheridgeabuttingupontheinsideoftheloop,andsotheimaginarylinecrossesnoloopingridge,whichisnecessary.

[Fig.335]

Figure336isaplainarch.Theendingridgeatthecentercannotbeconsideredanupthrustbecauseitdoesnotdeviatefromthegeneraldirectionofflowoftheridgesoneitherside.Noangleispresentastheendingridgedoesnotabutuponthecurvingridgewhichenvelopesit.[Pg83]

[Fig.336]

Figure337isaplainarchbecausethedotcannotbeconsideredadeltaasitisnotasthickandheavyasthesurroundingridges.



[Fig.337]

Figure338isatentedarchconsistingoftwoendingridgesandadelta.Theshortendingridgeisconsideredaridgebecauseitisslightlyelongatedandnotameredot.[Pg84]

[Fig.338]

Infigure339,theonlyquestioninvolvediswheretostoptracing.Theruleis:whentracingonaridgewithanupwardtrend,stopatthepointontheupwardtrendwhichisnearesttotherightdelta.Xisthepointinthispattern.

[Fig.339]

Infigure340,thequestioninvolvedisalsooneoftracing.Inthispattern,thetracingisnotonaridgewithanupwardtrend.Thetracing,therefore,iscontinueduntilapointnearesttotherightdelta,ortherightdeltaitself,isreached.Thistracingisameetingtracing.



[Fig.340]

Thereareafewconstantlyrecurringpatternswhich,thoughnotquestionableordoubtfulastheyappear,presentapeculiarlydifficultprobleminclassifying.Thepatternsreferredtoareusuallydoubleloops,thoughaccidentalwhorlsandloopssometimespresentthesameproblems.Thedifficultyariseswhenaloopissoelongatedthattherecurvedoesnotappearuntilneartheedgeofafullyrolledimpressionoranimpressionthatisrolledunusuallyfar,asinfigures341to344.

[Figs.341344]

Figure341,ifclassifiedasitappears,wouldbeanaccidentalwhorl.Figures342and343wouldbedoubleloops,andillustration344,aloop.Itwillbeobservedthattheseprintsarerolledmorefullythannormal.If,however,thenexttimetheprintsaretaken,theyarenotrolledquite[Pg85]sofar,thepatternswouldrequireaverydifferentclassification,andwouldshownoindicationofanyneedforreferencingtotheirtrueclassification.Theresultwouldbeafailuretoestablishanidentificationwiththeoriginalprints.Theonlywayinwhichsuchanerrormaybeavoidedistoclassifysuchimpressionsastheywouldappearifnotsofullyrolled,andtoconductareferencesearchintheclassificationwhichwouldbegiventothe



printswhenrolledtothefullestextent.Applyingthisrule,illustration341isatentedarch,referencedtoawhorl.Figures342and343areloops,referencedtowhorls.Figure344isaplainarch,referencedtoaloop.

Nosetrulecanpossiblybedevisedtoenableaclassifiertoknowwithcertaintywheretodrawthelinewhenitisdoubtfulwhichclassificationshouldbegivensuchaprint.Individualjudgmentistheonlystandard.Thetestis:ifthepattern,intheopinionoftheclassifier,isrolledtoonlyanormalwidth,itshouldbeclassifiedasitappears.Ifitseemstoberolledtoawidthbeyondthenormaldegree,itshouldbeclassifiedasifrolledonlytothenormaldegree.Age,weight,sizeoffingers(asseenin[Pg86]theplainimpressions),heavinessoftheridges,andexperienceofthetechnicianintakingfingerprintsareallfactorsinarrivingatthecorrectconclusion.Thenecessityforexercisingtheutmostcareindealingwiththistypeofpatterncannotbetoohighlyemphasized.

Thepatternsinfigures345and346alsohaveasecondloopneartheedgeoftheimpression.Inthesetwopatterns,however,thesecondloopisverynearthedeltaandconsequentlywillalmostinvariablyappeareventhoughnotrolledtothefullestextent.Theforegoingruleisnotappliedtothistypeofimpression.Bothareclassifiedasawhorlandreferencedtoalooptotakecareoftherarecontingencyofnonappearance.

[Figs.345346]

[Pg87]

CHAPTERIV

TheClassificationFormulaandExtensions

Theclassificationformula

Atthispointitisnecessarytomentionthatwhenprintsareclassified,markingsareindicatedatthebottomofeachfingerblocktoreflectthetype.Thefollowingsymbolsareused:

Undertheindexfingerstheappropriatecapitallettersshouldbeplacedforeverypatternexcepttheulnarloop.

Underallotherfingers,theappropriatesmalllettershouldbeplacedforeverypatternexcepttheulnarloopandthewhorlasfollows:

Arch a

TentedArch t

RadialLoop r

Ulnarloopsinanyfingeraredesignatedbyadiagonallineslantinginthedirectionoftheloop.

Whorlsinanyfingeraredesignatedbytheletter"W".Theclassificationformulamaybecomposedofthefollowingdivisions:

1.Primary 4.Major

2.Secondary 5.Final

3.Subsecondary 6.Key

Thepositionsintheclassificationlineforthesedivisionswhencompletelyappliedareasillustrated:

Key Major Primary Secondary Subsecondary Final

Divisions Classification Classification Classification

20 M 1 U IOI 10



L 1 U IOI

Key Major Primary Secondary

SecondsubsecondaryclassificationSubsecondary Final

Divisions Classification Classification Classification

4 O 5 U

SLMMMSIOI 10

I 17 U IOI

Theprimaryclassification:Forthepurposeofobtainingtheprimaryclassification,numericalvaluesareassignedtoeachoftheten[Pg88]fingerspacesasshowninfigure347.Whereverawhorlappearsitassumesthevalueofthespaceinwhichitisfound.Spacesinwhichtypesofpatternsotherthanwhorlsarepresentaredisregardedincomputingtheprimary.

Thevaluesareassignedasfollows:

FingersNo.1andNo.2 16





[Fig.347]

[Enlarge]

Infigure347,itwillbeobservedthattheoddfingers(Nos.1,3,5,7,9)containtheletterD,andthe



evenfingers(Nos.2,4,6,8,10)containtheletterN.TheDindicatesthatthevaluesofthesefingersrelatetothedenominator,theNthattheyrelatetothenumerator.Thesummationofthenumericalvaluesofthewhorltypepatterns,ifany,appearinginfingers1,3,5,7,9,plusone,isthedenominatoroftheprimary.Thesummationofthevaluesofthewhorls,ifany,infingers2,4,6,8,10,plusone,isthenumeratoroftheprimary.Wherenowhorlappearsinasetofimpressions,theprimary,therefore,wouldbe1over1.The1thatis[Pg89]assignedtothenumeratorandthedenominatorwhennowhorlsappearisalsoadded,forconsistency,tothevalueofthewhorlswhentheydoappear.ItwillbeunderstoodwhyitwasoriginallyassignedtothenowhorlgroupwhenitisconsideredhoweasilyazeromightbeconfusedwithanO,whichisthesymbolusedforanouterwhorltracing.

Toobtaintheprimaryfortheprintsinfigure347,thenumberofwhorlsappearingintheoddfingersisascertainedtobe2.Theirpositionsarenoted(1inNo.1and1inNo.7)andthevaluesassignedtowhorlsappearinginthosefingersareaddedtogether(16plus2=18).Tothissumthearbitrary1isadded,givingusthetotalof19,whichconstitutesthedenominatorforthissetofprints.Togetthenumerator,itisascertainedthatthereare3whorlsappearingintheevenfingers(2,4and6),thevaluesofwhichareaddedtogether(16plus8plus4=28).Tothissumthe1isadded,givinganumeratorof29,andacompleteprimaryof29over19.

Bytheword"whorl"ismeantalltypesofwhorls,includingplainwhorls,centralpocketloops,doubleloopsandaccidentals.Thetracingofthewhorldoesnotenterintothedeterminationoftheprimary.

Themethodofobtainingtheprimarycanprobablybeshownbestbyillustrations.Forexample,assumethatthereisawhorlintherightindexfingeronly.Thevalueofawhorlinthisfingeris16.When1over1isaddedtheresultingprimaryis17over1.Ifawhorlappearsintherightthumbandrightindexfinger,thevalueis16over16plus1over1givingaprimaryof17over17.Ifwhorlsappearinbothindexfingers,thevalueis16over2plus1over1givingaprimaryof17over3.Whenwhorlsappearinboththumbsandbothindexfingers,theprimaryis21over19andisobtainedbytheaddition16plus4plus1over16plus2plus1.Ifwhorlsappearinall10fingers,theprimaryis32over32(16plus8plus4plus2plus1plus1over16plus8plus4plus2plus1plus1).Itwillbenotedthattheprimaryclassificationsextendfrom1over1inthenowhorlgroupto32over32intheallwhorlgroup,providing1,024possiblecombinations.Thisdoesnotmeanthatthereare1,024evensubdivisionsofprintsaccordingtotheseprimaries.Justasthereisapreponderanceofloopswhenthetypesofpatternsareconsidered,thereisalsoapreponderanceofcertainprimaries,notably:the1over1primary,ornowhorlgroupthe17denominatorthe19denominatorthe28denominator,ofwhichthe31over28groupisthelargestandthe32denominator,including2largeprimarygroupsnamely,31over32and32over32.Asamatteroffact,the1over1group,asawhole,containsover25percentofthetotalnumberofprintsfiledintheFBI.Ontheotherhand,thereareanumberofprimarieswhichrarelyappear.Itfollows,therefore,thatwhenaprintisclassifiedinoneoftheselargergroupsitisnecessarytocompletetheclassificationtoagreaterextentthanisnecessaryinthemoreunusualprimaries,sothatthegrouptobesearchedissmallenoughforconvenience.[Pg90]

Inconnectionwiththecountingofwhorlvaluestoobtaintheprimary,itmightbenotedthatwhenthewhorlsoutnumbertheotherpatternsmorespeedcanbeachievedbycountingthosepatternsandsubtractingratherthanbyaddingthewhorls.Thisprocedureshouldnotbefolloweduntilenoughexperienceisacquiredsothatitmaybenotedataglancewherewhorlsarenotpresent.

Theexperiencedclassifiercantellinwhatfingerswhorlsarepresentbyaglanceataprimaryclassification.Forexample,aprimaryof5over17couldmeanthattherearewhorlsinthethumbsonly.



[Fig.348]

[Enlarge]

Thesecondaryclassification:Aftertheprimaryclassification,thefingerprintsaresubdividedfurtherbyusingasecondaryclassification.Beforegoingintodetail,itshouldbenotedthataftertheprimaryisobtainedtheentireremainingportionoftheclassificationformulaisbaseduponthearrangementoftheimpressionsappearingintherighthandasthenumeratorovertheimpressionsappearinginthelefthandasthedenominator.Thearrangementoftheevenovertheunevenfingersisdiscardedaftertheprimaryisobtained.Thesecondaryclassificationappearsjusttotherightofthefractionalnumeralswhichrepresenttheprimary.Itisshownintheformulabycapitallettersrepresentingthebasictypesofpatternsappearingintheindexfingersofeachhand,that[Pg91]oftherighthandbeingthenumeratorandthatofthelefthandbeingthedenominator(fig.348).Therearefivebasictypesofpatternswhichcanappear.

1.Arch A

2.TentedArch T

3.RadialLoop R

4.UlnarLoop U

5.Whorl W



[Fig.349]

[Enlarge]

Secondaryclassification(smalllettergroup):Printswithanarchortentedarchinanyfingeroraradialloopinanyexcepttheindexfingersconstitutethesmalllettergroupofthesecondaryclassification.Such"smallletters,"withtheexceptionofthoseappearingintheindexfingers,arebroughtupintotheclassificationformulaintheirproperrelativepositionsimmediatelyadjacenttotheindexfingers(fig.349).Adashisusedtoindicatetheabsenceofeachsmallletterbetweentheindexfingersandanothersmallletterorbetweentwosmallletters,as

1aUatand

1aUt.

1Ra1 1Ua

Thus,ifaradialloopappearsintherightthumb,[Pg92]thesmallletter"r"wouldbebroughtupinthenumeratorcolumnoftheclassificationformulaandplacedjusttotheleftofthecapitalletterrepresentingtheindexfinger.Similarly,ifanarchortentedarchoraradialloopwouldappearinthemiddle,ring,orlittlefingerofthehand,thesmallletterrepresentingsuchapatternwouldbeplacedontheclassificationlinetotherightofthesecondaryinthenumeratorcolumniftheletterispresentintherighthand,andinthedenominatorcolumnifinthelefthand.Whentwoormoresmalllettersofthesametypeoccurimmediatelyadjacenttoeachother,theyareindicatedthus:

1rU2aand

1aTaa.

1tU3a 1tA2at

Thesmalllettergroupsareofvitalimportancetotheclassificationsystem,astheyareofrelativelyinfrequentoccurrence,constitutingapproximately7to10percentofallpatterns.Generallyspeaking,sincethesepatternsareofsuchrareoccurrence,theirverypresenceoftenenablestheclassifiertodispensewiththeusualsubsecondaryclassificationandthemajordivisionwhichinthemajorityofcasesareusedinthelargergroups.

Thesubsecondaryclassification(groupingofloopsandwhorls):Inclassifyingprintsitisnecessarytosubdividethesecondarygroups.Thisisaccomplishedbygroupingaccordingtotheridgecountsofloopsandtheridgetracingsofwhorls.Thefirstofthegroupsfiledinorder,whichitwillbenecessarytososubdivide,wouldordinarilybethe

1R

1R

g

the science of fingerprints

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