men of invention and industry-第15部分

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extraordinary　sagacity；　hit　the　mark　in　his　report。　　〃One　is；〃　he

said；　〃by　a　watch　to　keep　time　exactly；　but；　by　reason　of　the

motion　of　a　ship；　and　the　variation　of　heat　and　cold；　wet　and

dry；　and　the　difference　of　gravity　in　different　latitudes；　such　a

watch　hath　not　yet　been　made。〃



An　Act　was　however　passed　in　the　Session　of　1714；　offering　a　very

large　public　reward　to　inventors：　10；000L。　to　any　one　who　should

discover　a　method　of　determining　the　longitude　to　one　degree　of　a

great　circle；　or　60　geographical　miles；　15；000L。　if　it　determined

the　same　to　two…thirds　of　that　distance；　or　40　geographical

miles；　and　20；000L。　if　it　determined　the　same　to　one…half　of　the

same　distance；　or　30　geographical　miles。　　Commissioners　were

appointed　by　the　same　Act；　who　were　instructed　that　〃one　moiety

or　half　part　of　such　reward　shall　be　due　and　paid　when　the　said

commissioners；　or　the　major　part　of　them；　do　agree　that　any　such

method　extends　to　the　security　of　ships　within　80　geographical

miles　of　the　shore；　which　are　places　of　the　greatest　danger；　and

the　other　moiety　or　half　part　when　a　ship；　by　the　appointment　of

the　said　commissioners；　or　the　major　part　of　them；　shall　actually

sail　over　the　ocean；　from　Great　Britain　to　any　such　port　in　the

West　Indies　as　those　commissioners；　or　the　major　part　of　them；

shall　choose　or　nominate　for　the　experiment；　without　losing　the

longitude　beyond　the　limits　before　mentioned。〃



The　terms　of　this　offer　indicate　how　great　must　have　been　the

risk　and　inconvenience　which　it　was　desired　to　remedy。　　Indeed；

it　is　almost　inconceivable　that　a　reward　so　great　could　be　held

out　for　a　method　which　would　merely　afford　security　within　eighty

geographical　miles！



This　splendid　reward　for　a　method　of　discovering　the　longitude

was　offered　to　the　worldto　inventors　and　scientific　men　of　all

countries　without　restriction　of　race；　or　nation；　or　language。　

As　might　naturally　be　expected；　the　prospect　of　obtaining　it

stimulated　many　ingenious　men　to　make　suggestions　and　contrive

experiments；　but　for　many　years　the　successful　construction　of　a

marine　time…keeper　seemed　almost　hopeless。　　At　length；　to　the

surprise　of　every　one；　the　prize　was　won　by　a　village

carpentera　person　of　no　school；　or　university；　or　college

whatever。



Even　so　distinguished　an　artist　and　philosopher　as　Sir

Christopher　Wren　was　engaged；　as　late　in　his　life　as　the　year

1720；　in　attempting　to　solve　this　important　problem。　　As　has　been

observed；　in　the　memoir　of　him　contained　in　the　'Biographia

Britannica；'＇3＇　〃This　noble　invention；　like　some　others　of　the

most　useful　ones　to　human　life；　seems　to　be　reserved　for　the

peculiar　glory　of　an　ordinary　mechanic；　who；　by　indefatigable

industry；　under　the　guidance　of　no　ordinary　sagacity；　hath

seemingly　at　last　surmounted　all　difficulties；　and　brought　it　to

a　most　unexpected　degree　of　perfection。〃　　Where　learning　and

science　failed；　natural　genius　seems　to　have　triumphed。



The　truth　is；　that　the　great　mechanic；　like　the　great　poet；　is

born；　not　made；　and　John　Harrison；　the　winner　of　the　famous

prize；　was　a　born　mechanic。　　He　did　not；　however；　accomplish　his

object　without　the　exercise　of　the　greatest　skill；　patience；　and

perseverance。　　His　efforts　were　long；　laborious；　and　sometimes

apparently　hopeless。　　Indeed；　his　life；　so　far　as　we　can

ascertain　the　facts；　affords　one　of　the　finest　examples　of

difficulties　encountered　and　triumphantly　overcome；　and　of

undaunted　perseverance　eventually　crowned　by　success；　which　is　to

be　found　in　the　whole　range　of　biography。



No　complete　narrative　of　Harrison's　career　was　ever　written。　

Only　a　short　notice　of　him　appears　in　the　'Biographia

Britannica；'　published　in　1766；　during　his　lifetime'the　facts

of　which　were　obtained　from　himself。　　A　few　notices　of　him　appear

in　the　'Annual　Register；'　also　published　during　his　lifetime。　

The　final　notice　appeared　in　the　volume　published　in　1777；　the

year　after　his　death。　　No　Life　of　him　has　since　appeared。　　Had　he

been　a　destructive　hero；　and　fought　battles　by　land　or　sea；　we

should　have　had　biographies　of　him　without　end。　　But　he　pursued　a

more　peaceful　and　industrious　course。　　His　discovery　conferred　an

incalculable　advantage　on　navigation；　and　enabled　innumerable

lives　to　be　saved　at　sea；　it　also　added　to　the　domains　of　science

by　its　more　exact　measurement　of　time。　　But　his　memory　has　been

suffered　to　pass　silently　away；　without　any　record　being　left　for

the　benefit　and　advantage　of　those　who　have　succeeded　him。　　The

following　memoir　includes　nearly　all　that　is　known　of　the　life

and　labours　of　John　Harrison。



He　was　born　at　Foulby；　in　the　parish　of　Wragby；　near　Pontefract；

Yorkshire；　in　March；　1693。　　His　father；　Henry　Harrison；　was

carpenter　and　joiner　to　Sir　Rowland　Winn；　owner　of　the　Nostell

Priory　estate。　　The　present　house　was　built　by　the　baronet　on　the

site　of　the　ancient　priory。　　Henry　Harrison　was　a　sort　of

retainer　of　the　family；　and　long　continued　in　their　Service。



Little　is　known　of　the　boy's　education。　　It　was　certainly　of　a

very　inferior　description。　　Like　George　Stephenson；　Harrison

always　had　a　great　difficulty　in　making　himself　understood；

either　by　speech　or　writing。　　Indeed；　every　board…school　boy　now

receives　a　better　education　than　John　Harrison　did　a　hundred　and

eighty　years　ago。　　But　education　does　not　altogether　come　by

reading　and　writing。　　The　boy　was　possessed　of　vigorous　natural

abilities。　　He　was　especially　attracted　by　every　machine　that

moved　upon　wheels。　　The　boy　was　'father　to　the　man。'　When　six

years　old；　and　lying　sick　of　small…pox；　a　going　watch　was　placed

upon　his　pillow；　which　afforded　him　infinite　delight。



When　seven　years　old　he　was　taken　by　his　father　to　Barrow；　near

Barton…on…Humber；　where　Sir　Rowland　Winn　had　another　residence

and　estate。　　Henry　Harrison　was　still　acting　as　the　baronet's

carpenter　and　joiner。　　In　course　of　time　young　Harrison　joined

his　father　in　the　workshop；　and　proved　of　great　use　to　him。　　His

opportunities　for　acquiring　knowledge　were　still　very　few；　but　he

applied　his　powers　of　observation　and　his　workmanship　upon　the

things　which　were　nearest　him。　　He　worked　in　wood；　and　to　wood　he

first　turned　his　attention。



He　was　still　fond　of　machines　going　upon　wheels。　　He　had　enjoyed

the　sight　of　the　big　watch　going　upon　brass　wheels　when　he　was　a

boy；　but；　now　that　he　was　a　workman　in　wood；　he　proposed　to　make

an　eight…day　clock；　with　wheels　of　this　material。　　He　made　the

clock　in　1713；　when　he　was　twenty　years　old；＇4＇　so　that　he　must

have　made　diligent　use　of　his　opportunities。　　He　had　of　course

difficulties　to　encounter；　and　nothing　can　be　accomplished

without　them；　for　it　is　difficulties　that　train　the　habits　of

application　and　perseverance。　　But　he　succeeded　in　making　an

effective　clock；　which　counted　the　time　with　regularity。　　This

clock　is　still　in　existence。　　It　is　to　be　seen　at　the　Museum　of

Patents；　South　Kensington；　and　when　we　visited　it　a　few　months

ago　it　was　going；　and　still　marking　the　moments　as　they　passed。　

It　is　contained　in　a　case　about　six　feet　high；　with　a　glass

front；　showing　a　pendulum　and　two　weights。　　Over　the　clock　is　the

following　inscription：



〃This　clock　was　made　at　Barrow；　Lincolnshire；　in　the　year　1715；　

by　John　Harrison；　celebrated　as　the　inventor　of　a　nautical

timepiece；　　or　chronometer；　which　gained　the　reward　of　20；000L。；

offered　by　the　Board　of　Longitude；　A。D。　1767。



〃This　clock　strikes　the　hour；　indicates　the　day　of　the　month；　and

with　one　exception　（the　escapement）　the　wheels　are　entirely　made

of　wood。〃



This；　however；　was　only　a　beginning。　　Harrison　proceeded　to　make

better　clocks；　and　then　he　found　it　necessary　to　introduce　metal；

which　was　more　lasting。　　He　made　pivots　of　brass；　which　moved

more　conveniently　in　sockets　of　wood　with　the　use　of　oil。　　He

also　caused　the　teeth　of　his　wheels　to　run　against　cylindrical

rollers　of　wood；　fixed　by　brass　pins；　at　a　proper　distance　from

the　axis　of　the　pinions；　and　thus　to　a　considerable　extent

removed　the　inconveniences　of　friction。



In　the　meantime　Harrison　eagerly　improved　every　incident　from

which　he　might　derive　further　information。　　There　was　a　clergyman

who　came　every　Sunday　to　the　village　to　officiate　in　the

neighbourhood；　and　having　heard　of　the　sedulous　application　of

the　young　carpenter；　he　lent　him　a　manuscript　copy　of　Professor

Saunderson's　discourses。　　That　blind　professor　had　prepared

several　lectures　on　natural　philosophy　for　the　use　of　his

students；　though　they　were　not　intended　for　publication。　　Young

Harrison　now　proceeded　to　copy　them　out；　together　with　the

diagrams。　　Sometimes；　indeed；　he　spent　the　greater　part　of　the

night　in　writing　or　drawing。



As　part　of　his　business；　he　undertook　to　survey　land；　and　to

repair　clocks　and　watches；　besides　carrying　on　his　trade　of　a

carpenter。　　He　soon　obtained　a　considerable　knowledge　of　what　had

been　done　in　clocks　and　watches；　and　was　able　to　do　not　only　what

the　best　professional　workers　had　done；　but　to　strike　out

entirely　new　lights　in　the　clock　and　watch…making　business。　　He

found　out　a　method　of　diminishing　friction　by　adding　a　joint　to

the　pallets　of　the　pendulum；　whereby　they　were　made　to　work　in

the　nature　of　rollers　of　a　large　radius；　without　any　sliding；　as

usual；　upon　the　teeth　of　the　wheel。　　He　constructed　a　clock　on

the　recoiling　principle；　which　went　perfectly；　and　never　lost　a

minute　within　fourteen　years。　　Sir　Edmund　Denison　Beckett　says

that　he　invented　this　method　in　order　to　save　himself　the　trouble

of　going　so　frequently　to　oil　the　escapement　of　a　turret　clock；

of　which　he　had　charge；　though　there　were　other　influences　at

work　besides　this。



But　his　most　important　invention；　at　this　early　period　of　his

life；　was　his　compensation　pendulum。　　Every　one　knows　that　metals

expand　with　heat　and　contract　by　cold。　　Th