industrial biography-第69章

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accumulate　about　500L。；　which　he　thought　would　be　enough　for　his

purpose；　and　he　accordingly　proceeded；　in　1817；　to　take　a　small

workshop　in　Prospect　Place；　Newington　Butts；　where　he　began　business

as　a　mechanical　draughtsman　and　manufacturer　of　small　machinery

requiring　first…class　workmanship。



From　the　time　when　he　took　his　first　gratuitous　lessons　in　drawing

from　Peter　Nicholson；　at　Glasgow；　in　1807；　he　had　been　steadily

improving　in　this　art；　the　knowledge　of　which　is　indispensable　to

whoever　aspires　to　eminence　as　a　mechanical　engineer；until　by

general　consent　Clement　was　confessed　to　stand　unrivalled　as　a

draughtsman。　　Some　of　the　very　best　drawings　contained　in　the

Transactions　of　the　Society　of　Arts；　from　the　year　1817

downwards；especially　those　requiring　the　delineation　of　any

unusually　elaborate　piece　of　machinery；proceeded　from　the　hand　of

Clement。　　In　some　of　these；　he　reached　a　degree　of　truth　in　mechanical

perspective　which　has　never　been　surpassed。*

　＇footnote。。。

See　more　particularly　The　Transactions　of　the　Society　for　the

Encouragement　of　Arts；　vol。　xxxiii。　（l8l7）；　at　pp。　74；l57；l60；175；208

（an　admirable　drawing；　of　Mr。　James　Allen's　Theodolite）；　vol。　xxxvi。

（1818）；　pp。　28；176　（a　series　of　remarkable　illustrations　of　Mr。

Clement's　own　invention　of　an　Instrument　for　Drawing　Ellipses）；　vol。

xliii。　（1825）；　containing　an　illustration　of　the　Drawing　Table

invented　by　him　for　large　drawings；　vol。　xlvi。　（1828）；　containing　a

series　of　elaborate　illustrations　of　his　Prize　Turning　Lathe；　and

xlviii。　1829；　containing　illustrations　of　his　Self…adjusting　Double

Driver　Centre　Chuck。

　。。。＇

To　facilitate　his　labours；　he　invented　an　extremely　ingenious

instrument；　by　means　of　which　ellipses　of　all　proportions；　as　well　as

circles　and　right　lines；　might　be　geometrically　drawn　on　paper　or　on

copper。　　He　took　his　idea　of　this　instrument　from　the　trammel　used　by

carpenters　for　drawing　imperfect　ellipses；　and　when　he　had　succeeded

in　avoiding　the　crossing　of　the　points；　he　proceeded　to　invent　the

straight…line　motion。　　For　this　invention　the　Society　of　Arts　awarded

him　their　gold　medal　in　1818。　　Some　years　later；　he　submitted　to　the

same　Society　his　invention　of　a　stand　for　drawings　of　large　size。　　He

had　experienced　considerable　difficulty　in　making　such　drawings；　and

with　his　accustomed　readiness　to　overcome　obstacles；　he　forthwith　set

to　work　and　brought　out　his　new　drawing…table。



As　with　many　other　original…minded　mechanics；　invention　became　a

habit　with　him；　and　by　study　and　labour　he　rarely　failed　in　attaining

the　object　which　he　had　bent　his　mind　upon　accomplishing。　　Indeed；

nothing　pleased　him　better　than　to　have　what　he　called　〃a　tough　job；〃

as　it　stimulated　his　inventive　faculty；　in　the　exercise　of　which　he

took　the　highest　pleasure。　　Hence　mechanical　schemers　of　all　kinds

were　accustomed　to　resort　to　Clement　for　help　when　they　had　found　an

idea　which　they　desired　to　embody　in　a　machine。　　If　there　was　any

value　in　their　idea；　none　could　be　more　ready　than　he　to　recognise

its　merit；　and　to　work　it　into　shape；　but　if　worthless；　he　spoke　out

his　mind　at　once；　dissuading　the　projector　from　wasting　upon　it

further　labour　or　expense。



One　of　the　important　branches　of　practical　mechanics　to　which　Clement

continued　through　life　to　devote　himself；　was　the　improvement　of

self…acting　tools；　more　especially　of　the　slide…lathe。　　He　introduced

various　improvements　in　its　construction　and　arrangement；　until　in

his　hands　it　became　as　nearly　perfect　as　it　was　possible　to　be。　　In

1818；　he　furnished　the　lathe　with　a　slide　rest　twenty…two　inches

long；　for　the　purpose　of　cutting　screws；　provided　with　the　means　of

self…correction；　and　some　years　later；　in　1827；　the　Society　of　Arts

awarded　him　their　gold　Isis　medal　for　his　improved　turning…lathe；

which　embodied　many　ingenious　contrivances　calculated　to　increase　its

precision　and　accuracy　in　large　surface…turning。



The　beautiful　arrangements　embodied　in　Mr。　Clement's　improved　lathe

can　with　difficulty　be　described　in　words；　but　its　ingenuity　may　be

inferred　from　a　brief　statement　of　the　defects　which　it　was　invented

to　remedy；　and　which　it　successfully　overcame。　　When　the　mandrill　of　a

lathe；　having　a　metal　plate　fixed　to　it；　turns　round　with　a　uniform

motion；　and　the　slide　rest　which　carries　the　cutter　is　moving　from

the　circumference　of　the　work　to　the　centre；　it　will　be　obvious　that

the　quantity　of　metal　passing　over　the　edge　of　the　cutter　at　each

revolution；　and　therefore　at　equal　intervals　of　time；　is　continually

diminishing；　in　exact　proportion　to　the　spiral　line　described　by　the

cutter　on　the　face　of　the　work。　　But　in　turning　metal　plates　it　is

found　very　in　expedient　to　increase　the　speed　of　the　work　beyond　a

certain　quantity；　for　when　this　happens；　and　the　tool　passes　the　work

at　too　great　a　velocity；　it　heats；　softens；　and　is　ground　away；　the

edge　of　the　cutter　becomes　dull；　and　the　surface　of　the　plate　is

indented　and　burnished；　instead　of　being　turned。　　Hence　loss　of　time

on　the　part　of　the　workman；　and　diminished　work　on　the　part　of　the

tool；　results　which；　considering　the　wages　of　the　one　and　the　capital

expended　on　the　construction　of　the　other；　are　of　no　small

importance；　for　the　prime　objects　of　all　improvement　of　tools　are；

economy　of　time　and　economy　of　capitalto　minimize　labour　and　cost；

and　maximize　result。



The　defect　to　which　we　have　referred　was　almost　the　only　remaining

imperfection　in　the　lathe；　and　Mr。　Clement　overcame　it　by　making　the

machine　self…regulating；　so　that；　whatever　might　be　the　situation　of

the　cutter；　equal　quantities　of　metal　should　pass　over　it　in　equal

times；the　speed　at　the　centre　not　exceeding　that　suited　to　the　work

at　the　circumference；while　the　workman　was　enabled　to　convert　the

varying　rate　of　the　mandrill　into　a　uniform　one　whenever　he　chose。

Thus　the　expedients　of　wheels；　riggers；　and　drums；　of　different

diameters；　by　which　it　had　been　endeavoured　to　alter　the　speed　of　the

lathe…mandrill；　according　to　the　hardness　of　the　metal　and　the

diameter　of　the　thing　to　be　turned；　were　effectually　disposed　of。

These；　though　answering　very　well　where　cylinders　of　equal　diameter

had　to　be　bored；　and　a　uniform　motion　was　all　that　was　required；　were

found　very　inefficient　where　a　Plane　surface　had　to　be　turned；　and　it

was　in　such　cases　that　Mr。　Clement's　lathe　was　found　so　valuable。　　By

its　means　surfaces　of　unrivalled　correctness　were　produced；　and　the

slide…lathe；　so　improved；　became　recognised　and　adopted　as　the　most

accurate　and　extensively　applicable　of　all　machine…tools。



The　year　after　Mr。　Clement　brought　out　his　improved　turning…lathe；　he

added　to　it　his　self…adjusting　double　driving　centre…chuck；　for　which

the　Society　of　Arts　awarded　him　their　silver　medal　in　1828。　　In

introducing　this　invention　to　the　notice　of　the　Society；　Mr。　Clement

said；　〃Although　I　have　been　in　the　habit　of　turning　and　making

turning…lathes　and　other　machinery　for　upwards　of　thirty…five　years；

and　have　examined　the　best　turning…lathes　in　the　principal

manufactories　throughout　Great　Britain；　I　find　it　universally

regretted　by　all　practical　men　that　they　cannot　turn　anything

perfectly　true　between　the　centres　of　the　lathe。〃　　It　was　found　by

experience；　that　there　was　a　degree　of　eccentricity；　and　consequently

of　imperfection；　in　the　figure　of　any　long　cylinder　turned　while

suspended　between　the　centres　of　the　lathe；　and　made　to　revolve　by

the　action　of　a　single　driver。　　Under　such　circumstances　the　pressure

of　the　tool　tended　to　force　the　work　out　of　the　right　line　and　to

distribute　the　strain　between　the　driver　and　the　adjacent　centre；　so

that　one　end　of　the　cylinder　became　eccentric　with　respect　to　the

other。　　By　Mr。　Clement's　invention　of　the　two…armed　driver；　which　was

self…adjusting；　the　strain　was　taken　from　the　centre　and　divided

between　the　two　arms；　which　being　equidistant　from　the　centre；

effect