an autobiography-第26章

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e　highest　qualities　of　the　skilled　workman。　　No　one　that　I　ever　met　with　could　go　beyond　Henry　Maudslay　himself　in　his　dexterous　use　of　the　file。　　By　a　few　masterly　strokes　he　could　produce　plane　surfaces　so　true　that　when　their　accuracy　was　tested　by　a　standard　plane　surface　of　absolute　truth；　they　were　never　found　defective；　neither　convex；　nor　concave；　nor　〃cross…winding；〃that　is；　twisted。

The　importance　of　having　such　Standard　Planes　caused　him　to　have　many　of　them　placed　on　the　benches　beside　his　workmen；　by　means　of　which　they　might　at　once　conveniently　test　their　work。　　Three　of　each　were　made　at　a　time；　so　that　by　the　mutual　rubbing　of　each　on　each　the　projecting　surfaces　were　effaced。　　When　the　surfaces　approached　very　near　to　the　true　plane；　the　still　projecting　minute　points　were　carefully　reduced　by　hard　steel　scrapers；　until　at　last　the　standard　plane　surface　was　secured。　　When　placed　over　each　other　they　would　float　upon　the　thin　stratum　of　air　between　them　until　dislodged　by　time　and　pressure。　　When　they　adhered　closely　to　each　other；　they　could　only　be　separated　by　sliding　each　off　each。　　This　art　of　producing　absolutely　plane　surfaces　is；　I　believe；　a　very　old　mechanical　〃dodge。〃　But；　as　employed　by　Maudslay's　men；　it　greatly　contributed　to　the　improvement　of　the　work　turned　out。　　It　was　used　for　the　surfaces　of　slide　valves；　or　wherever　absolute　true　plane　surfaces　were　essential　to　the　attainment　of　the　best　results；　not　only　in　the　machinery　turned　out；　but　in　educating　the　taste　of　his　men　towards　first…class　workmanship。

Maudslay's　love　of　accuracy　also　led　him　to　distrust　the　verdicts　given　by　the　employment　of　the　ordinary　callipers　and　compasses　in　determining　the　absolute　or　relative　dimensions　of　the　refined　mechanism　which　he　delighted　to　construct　with　his　own　hands。　So　much　depended　upon　the　manner　in　which　the　ordinary　measuring　instruments　were　handled　and　applied　that　they　sometimes　failed　to　give　the　required　verdict　as　to　accuracy。　　In　order；　therefore；　to　get　rid　of　all　difficulties　in　this　respect；　he　designed　and　constructed　a　very　compact　and　handy　instrument　which　he　always　had　on　his　bench　beside　his　vice。　　He　could　thus；　in　a　most　accurate　and　rapid　manner；　obtain　the　most　reliable　evidence　as　to　the　relative　dimensions；　in　length；　width；　or　diameter；　of　any　work　which　he　had　in　hand。　　In　consequence　of　the　absolute　truth　of　the　verdicts　of　the　instrument；　he　considered　it　as　a　Court　of　Final　Appeal；　and　humorously　called　it　〃The　Lord　Chancellor。〃

＇Image＇　　Maudslay's　〃Lord　Chancellor〃

This　trustworthy　〃Companion　of　the　Bench〃　consisted　of　a　very　substantial　and　inflexible　bed　or　base　of　hard　brass。　　At　one　end　of　it　was　a　perfectly　hardened　steel　surface　plate；　having　an　absolutely　true　flat　or　plane　face；　against　which　one　end　or　side　of　the　object　to　be　measured　was　placed；　whilst　a　similar　absolutely　true　plane　surface　of　hardened　steel　was　advanced　by　means　of　a　suitable　fine　thread　screw；　until　the　object　to　be　measured　was　just　delicately　in　contact　with　it。　The　object　was；　as　it　were；　between　the　jaws　of　a　vice；　but　without　any　squeezebeing　just　free；　which　could　be　easily　ascertained　by　feeling。　　These　two　absolutely　plane　surfaces；　between　which　the　object　lay；　had　their　distances　apart　easily　read　off　from　the　scale　engraved　on　the　bed　of　the　instrument；　in　inches　and　tenth　parts　of　an　inch；　while　the　disk…head　or　handle　of　the　screw　was　divided　on　its　edge　rim　into　hundredth　or　thousandth　parts；　as　these　bore　an　exact　metrical　relation　to　the　pitch　of　the　screw　that　moved　the　parallel　steel　faces　of　the　measuring　vice　（as　I　may　term　it）　nearer　or　farther　apart。

Not　only　absolute　measure　could　be　obtained　by　this　means；　but　also　the　amount　of　minute　differences　could　be　ascertained　with　a　degree　of　exactness　that　went　quite　beyond　all　the　requirements　of　engineering　mechanism；　such；　for　instance；　as　the　thousandth　part　of　an　inch！　It　might　also　have　been　divided　so　far　as　a　millionth　part　of　an　inch；　but　these　infinitesimal　fractions　have　really　nothing　to　do　with　the　effective　machinery*　　＇footnote。。。　I　may　mention　another　saying　of　Mr。　Maudslay's。　　Besides　his　observation　that　〃in　going　from　London　to　Greenwich　we　must　not　go　round　by　Inverness；〃　he　said；　〃We　must　not　become　too　complicated　with　our　machinery。　　Remember　the　get…at…ability　of　parts。　　If　we　go　on　as　some　mechanics　are　doing；　we　shall　soon　be　boiling　our　eggs　with　a　chronometer！〃　　。。。＇　that　comes　forth　from　our　workshops；　and　merely　show　the　mastery　we　possess　over　materials　and　mechanical　forms。　　The　original　of　this　measuring　machine　of　Maudslay's　was　exhibited　at　the　Loan　Collection　at　South　Kensington　in　1878。　　It　is　now　treasured　up；　with　other　relics　of　his　handiwork；　in　a　cabinet　at　the　Lambeth　works。　　While　writing　upon　this　subject　it　may　be　worthy　of　remark；　that　the　employment　of　a　screw　as　the　means　of　adjusting　the　points　or　reference　marks　of　a　measuring　instrument；　for　the　ascertainment　of　minute　distances　between　objects；　was　first　effected　by　William　Gascoigne；　about　the　year　1648。　There　can　be　no　doubt　that　he　was　the　inventor　of　the　Micrometeran　instrument　that；　when　applied　（as　he　first　did　so）　to　the　eye…piece　of　the　Telescope；　has　been　the　means　of　advancing　the　science　of　astronomy　to　its　present　high　position　（See　Grant's　History　of　Astronomy；　p。　453）

I　had　abundant　occupation　for　my　leisure　time　after　my　regular　attendance　at　the　factory　was　over。　　I　had　not　only　the　opportunity　of　studying　mechanics；　but　of　studying　men。　　It　is　a　great　thing　to　know　the　character　of　those　who　are　over　you　as　well　as　those　who　are　under　you。　　It　is　also　well　to　know　the　character　of　those　who　are　associated　with　you　in　your　daily　work。　　I　became　intimate　with　the　foremen　and　with　many　of　the　skilled　workmen。　　From　them　I　learnt　a　great　deal。　Let　me　first　speak　of　the　men　of　science　who　occasionally　frequented　Maudslay's　private　workshop。　　They　often　came　to　consult　him　on　subjects　with　which　he　was　specially　acquainted。

Among　Mr。　Maudslay's　most　frequent　visitors　were　General　Sir　Samuel　Bentham；　Mr。　Barton；　director　of　the　Royal　Mint；　Mr。　Bryan　Donkin；　Mr。　Faraday；　and　Mr。　Chantrey；　the　sculptor。　　As　Mr。　Maudslay　wished　me　to　be　at　hand　to　give　him　any　necessary　assistance；　I　had　the　opportunity　of　listening　to　the　conversation　between　him　and　these　distinguished　visitors。　　Sir　Samuel　Bentham　called　very　often。　He　had　been　associated　with　Maudslay　during　the　contrivance　and　construction　of　the　block　machinery。　　He　was　brother　of　the　celebrated　Jeremy　Bentham；　and　he　applied　the　same　clear　common…sense　to　mechanical　subjects　which　the　other　had　done　to　legal；　social；　and　political　questions。　　It　was　in　the　highest　degree　interesting　and　instructive　to　hear　these　two　great　pioneers　in　the　history　and　application　of　mechanics　discussing　the　events　connected　with　the　block…making　machinery。　　In　fact；　Maudslay's　connection　with　the　subject　had　led　to　the　development　of　most　of　our　modern　engineering　tools。　　They　may　since　have　been　somewhat　altered　in　arrangement；　but　not　in　principle。　　Scarcely　a　week　passed　without　a　visit　from　the　General。　He　sat　in　the　beautiful　workshop；　where　he　always　seemed　so　happy。　　It　was　a　great　treat　to　hear　him　and　Maudslay　〃fight　their　battles　o'er　again；〃　in　recounting　the　difficulties；　both　official　and　mechanical；　over　which　they　had　so　gloriously　triumphed。

At　the　time　when　I　listened　to　their　conversation；　the　great　work　in　hand　was　the　organisation　of　a　systematic　series　of　experiments　on　the　hulls　of　steamships；　with　the　view　of　determining　the　laws　of　resistance　on　their　being　propelled　through　the　sea　by　a　power　other　than　those　of　winds　and　sails。　　The　subject　was　as　complex　as　it　was　interesting　and　important。　　But　it　had　to　be　put　to　the　test　of　actual　experiment。　　This　was　done　in　the　first　place　by　large　models　of　hulls；　so　as　to　ascertain　at　what　point　the　curves　of　least　resistance　could　be　applied。　　Their　practical　correctness　was　tested　by　careful　experiment　in　passing　them　through　water　at　various　velocities；　to　record　which　conditions　special　instruments　were　contrived　and　executed。　　These；　as　well　as　the　preparation　of　large　models　of　hulls；　embodying　the　various　improved　〃lines；〃　occupied　a　considerable　portion　of　the　time　that　I　had　the　good　fortune　to　spend　in　Mr。　Maudslay's　private　workshop。

Mr。　Barton　of　the　Royal　Mint　was　quite　a　〃crony〃　of　Maudslay's。　He　called　upon　him　often　with　respect　to　the　improvements　for　stamping　the　current　coin　of　the　realm。　　Bryan　Donkin　was　also　associated　with　Maudslay　and　Barton　on　the　subject　of　the　national　standard　of　the　yard　measure。　　But　perhaps　Mr。　Chantrey　was　the　most　attractive　visitor　at　the　private　workshop。　　He　had　many　a　long　interview　with　Maudslay　with　respect　to　the　planning　and　arranging　of　a　small　foundry　at　his　studio；　by　means　of　which　he　might　cast　his　bronze　statues　under　his　own　superintendence。　　Mr。　Maudslay　entered　con　amore　into　the　subject；　and　placed　his　skill　and　experience　entirely　at　Chantrey's　service。　He　constructed　the　requisite　furnaces；　cranes；　and　other　apparatus；　at　Chantrey's　studio；　and　it　may　be　enough　to　state　that；　when　brought　into　operation；　they　yielded　the　most　satisfactory　results。

Among　my　most　intelligent　private　friends　in　London　were　George　Cundell　and　his　two　brothers。　　They　resided　near　my　lodgings；　and　I　often　visited　them　on　Saturday　evenings。　　They　were　most　kind；　gentle；　and　genial。　　The　eldest　brother　was　in　Sir　William　Forbes's　bank。　George　was　agent　for　Mr。　Patrick　Maxwell　Stuart　in　connection　with　his　West　India　estates；　and　the　third　brother　was　his　assistant。　The　elder　brother　was　an　admirable　performer　on　the　violoncello；　and　he　treated　us　during　these　Saturday　evenings　with　noble　music　from　Beethoven　and　Mozart。　　My　special　friend　George　was　known　amongst　us　as　〃the　worthy　master。〃　　He　was　thoroughly　versed　in　general　science；　and　was　moreover　a　keen　politician。　　He　had　the　most　happy　faculty　of　treating　complex　subjects；　both　in　science　and　politics；　in　a　thoroughly　common…sense　manner。　　His　two　brothers　had　a　fine　feeling　for　art；　and；　indeed；　possessed　no　small　skill　as　practical　artists。　With　companions　such　as　these；　gifted　with　a　variety　of　tastes；　I　spent　many　of　my　Saturday　evenings　most　pleasantly　and　profitably。　They　were　generally　concluded　with　a　glass　of　beer　of　〃the　worthy　master's〃　own　brewing。

When　the　season　of　the　year　and　the　state　of　the　weather　were　suitable　I　often　joined　this　happy　fraternity　in　long　and　delightful　Sunday　walks　to　various　interesting　places　round　London。　　Our　walks　included　Waltham　Abbey；　Waltham　Cross；　Eltham　Palace；　Hampton　Court；　Epping　Forest；　and　many　other　interesting　places　of　resort。　　When　the　weather　was　unfavourable　my　principal　resort　was　Westminster　Abbey；　where；　besides　the　beautifully…conducted　service　and　the　noble　anthems；　I　could　admire　the　glory　of　the　architecture；　and　the　venerable　tombs；　under　which　lay　the　best　and　bravest。　　I　used　generally　to　sit　at　a　point　from　which　I　could　see　the　grand　tomb　of　Aylmer　de　Vallance　with　its　magnificent　surroundings　of　quaint　and　glorious　architecture。　It　was　solemn；　and　serious　also；　to　think　of　the　many　generations　who　had　filled　the　abbey；