an autobiography-第85节

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meter；　such　pistons　will　be　found　to　perform　perfectly　all　their　functions；　and　with　a　total　absence　of　friction　as　a　direct　result　of　the　absence　of　packing。　　By　the　aid　of　our　improved　machine　tools；　cylinders　can　now　be　bored　with　such　perfect　accuracy；　and　the　pistons　be　fitted　to　them　with　such　absolute　exactness；　that　the　small　quantity　of　water　which　the　steam　always　deposits　on　the　upper　side　of　the　piston；　not　only　serves　as　a　frictionless　packing；　but　also　serves　as　a　lubricant　of　the　most　appropriate　kind。　　I　have　applied　the　same　kind　of　piston　to　ordinary　water…pumps；　with　similar　excellent　results。　　In　most　cases　of　right　packed　pistons　we　spend　a　shillingto　save　sixpence　a　not　unfrequent　result　of　〃so…called〃　refined　improvements。


1836。　An　instantaneous　Mode　of　producing　graceful　Curves；　suitable　for　　　　　　　designing　Vases　and　other　graceful　objects　in　Pottery　and　Glass。

The　mode　referred　to　consists　in　giving　a　rapid　〃switch〃　motion　to　a　pencil　upon　a　piece　of　paper；　or　a　cardboard；　or　a　smooth　metal　plate；　and　then　cutting　out　the　curve　so　produced；　and　employing　it　as　a　pattern　or　〃template；〃　to　enable　copies　to　be　traced　from　it。　When　placed　at　equal　distances；　and　at　equal　angles　on　each　side　of　a　central　line；　so　as　to　secure　perfect　symmetry　of　form　according　to　the　nature　of　the　required　design；　the　beauty　of　these　〃instantaneous〃　curves；　as　I　term　them；　arises　from　the　entire　absence　of　any　sudden　variation　in　their　course。　　This　is　due　to　the　momentum　of　the　hand　when　〃switching〃　the　pencil　at　a　high　velocity　over　the　paper。　By　such　simple　means　was　the　beautiful　curve　produced；　which　is　given　on　the　following　page。　　It　was　produced　〃in　a　twinkling；〃　if　I　may　use　the　term　to　express　the　rapidity　with　which　it　was　〃switched。〃　The　chief　source　of　the　gracefulness　of　these　curves　consists　in　the　almost　imperceptible　manner　in　which　they　pass　in　their　course　from　one　degree　of　curvature　into　another。　　I　have　had　the　pleasure　of　showing　this　simple　mode　of　producing　graceful　curves　to　several　potters；　who　have　turned　the　idea　to　good　account。　　The　illustrative　figures　on　the　next　page　have　all　been　drawn　from　〃templates〃　whose　curves　were　〃switched〃　in　the　manner　of　Fig。　A。

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1836。　A　Machine　for　planing　the　smaller　or　detail　parts　of　Machinery；　　　　　　　whether　Flat　or　Cylindrical。

Although　the　introduction　of　the　planing　machine　into　the　workshops　of　mechanical　engineers　yielded　results　of　the　highest　importance　in　perfecting　and　economising　the　production　of　machinery　generally；　yet；　as　the　employment　of　these　valuable　machine　tools　was　chiefly　intended　to　assist　in　the　execution　of　the　larger　parts　of　machine　manufacture；　a　very　considerable　proportion　of　the　detail　parts　still　continued　to　be　executed　by　hand　labour；　in　which　the　chisel　and　the　file　were　the　chief　instruments　employed。　　The　results　were　consequently　very　unsatisfactory；　both　as　regards　inaccuracy　and　costliness。

＇image＇

With　the　desire　of　rendering　the　valuable　services　of　the　Planing　Machine　applicable　to　the　smallest　detail　parts　of　machine　manufacture；　I　designed　a　simple　and　compact　modification　of　it；　such　as　should　enable　any　attentive　lad　to　execute　all　the　detail　parts　of　the　machines　in　so　unerring　and　perfect　a　manner　as　not　only　to　rival　the　hand　work　of　the　most　skilful　mechanic；　but　also　at　such　a　reduced　cost　as　to　place　the　most　active　hand　workman　far　into　the　background。　The　contrivance　I　refer　to　is　usually　known　as　〃Nasmyth's　Steam　Arm。〃　None　but　those　who　have　had　ample　opportunities　of　watching　the　process　of　executing　the　detail　parts　of　machines；　can　form　a　correct　idea　of　the　great　amount　of　time　that　is　practically　wasted　and　unproductive；　even　when　highly…skilled　and　careful　workmen　are　employed。　　They　have　so　frequently　to　stop　working；　in　order　to　examine　the　work　in　hand；　to　use　the　straight　edge；　the　square；　or　the　calipers；　to　ascertain　whether　they　are　〃working　correctly。〃　　During　that　interval；　the　work　is　making　no　progress：　and　the　loss　of　time　on　this　account　is　not　less　than　one…sixth　of　the　working　hours；　and　sometimes　much　more；　though　all　this　lost　time　is　fully　paid　for　in　wages。

＇Image＇　　Apparatus　for　enabling　the　machine　to　execute　segmented　work

But　by　the　employment　of　such　a　machine　as　I　describe；　even　when　placed　under　the　superintendence　of　well…selected　intelligent　lads；　in　whom　the　faculty　of　good　sight　and　nicety　of　handling　is　naturally　in　a　high　state　of　perfection；　any　deficiency　in　their　physical　strength　is　amply　compensated　by　these　self…acting　machines。　　The　factory　engine　supplies　the　labour　or　the　element　of　Force；　while　the　machines　perform　their　work　with　practical　perfection。　　The　details　of　machinery　are　thus　turned　out　with　geometrical　accuracy；　and　are　in　the　highest　sense　fitted　to　perform　their　intended　purposes。


1837。　Solar　Ray　Origin　of　the　form　of　the　Egyptian　Pyramids；　Obelisks；　　　　　　　etc。

This　will　be　found　described　summarily　in　the　next　and　final　chapter。


1837。　Method　of　reversing　the　action　of　Slide　Lathes。

In　the　employment　of　Slide　Turning　Lathes；　it　is　of　great　advantage　to　be　able　to　reverse　the　motion　of　the　Slide　so　as　to　enable　the　turning　tool　to　cut　towards　the　Head　of　the　Lathe　or　away　from　it；　and　also　to　be　able　to　arrest　the　motion　of　the　Slide　altogether；　while　all　the　other　functions　of　the　lathe　are　continued　in　action。　　All　these　objects　are　attained　by　the　simple　contrivance　represented　in　the　annexed　illustration。

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It　consists　of　a　lever　E；　moving　on　a　stud…pin　S；　attached　to　the　back　of　the　head　stock　of　the　lathe　T。　　This　lever　carries　two　wheels　of　equal　diameter　marked　B　and　G。　　These　wheels　can　pitch　into　a　corresponding　wheel　A；　fixed　on　the　back　end　of　the　lay　spindle。　When　the　handle　of　the　lever　E　is　depressed　（as　seen　in　the　drawing）　the　wheel　B　is　in　gear　with　wheel　A。　　while　C　is　in　gear　with　the　slidescrew　wheel　D；　and　so　moves　the　slide　（say　from　the　Head　Stock　of　the　lathe）。　　On　the　other　hand；　when　the　lever　E　is　elevated　in　position　E〃；　wheel　B　is　taken　out　of　gear　with　A；　while　G　is　put　in　gear　with　A；　and　B　is　put　in　gear　with　D；　and　thus　the　Slide　is　caused　to　move　towards　the　Head　Stock　of　the　lathe。　　Again；　where　it　is　desired　to　arrest　the　motion　of　the　Slide　altogether；　or　for　a　time；　as　occasion　may　require；　the　lever　handle　is　put　into　the　intermediate　position　E'；　which　entirely　severs　the　communication　between　A　and　D；　and　so　arrests　the　motion　of　the　slide。　　This　simple　contrivance　effectually　served　all　its　purposes；　and　was　adopted　by　many　machine　tool…makers　and　engineers。


1838。　Self…adjusting　Bearings　for　the　Shafts　of　Machinery

A　frequent　cause　of　undue　friction　and　heating　of　rapidly　rotating　machinery　arises　from　some　inaccuracy　or　want　of　due　parallelism　between　the　rotating　shaft　or　spindle　and　its　bearing。　　This　is　occasioned　in　most　cases　by　some　accidental　change　in　the　level　of　the　supports　of　the　bearings。　　Many　of　the　bearings　are　situated　in　dark　places；　and　cannot　be　seen。　　There　are　others　that　are　difficult　of　accessas　in　the　case　of　bearings　of　screw…propeller　shafts。　Serious　mischief　may　result　before　the　heating　of　the　bearing　proclaims　its　dangerous　condition。　　In　some　cases　the　timber　work　is　set　on　fire；　which　may　result　in　serious　consequences。

In　order　to　remove　the　cause　of　such　serious　mischief；　I　designed　an　arrangement　of　bearing；　which　enabled　it；　and　the　shaft　working　in　it；　to　mutually　accommodate　themselves　to　each　other　under　all　circumstances；　and　thus　to　avoid　the　danger　of　a　want　of　due　and　mutual　parallelism　in　their　respective　axes。　　This　arrangement　consisted　in　giving　to　the　exterior　of　the　bearing　a　spherical　form；　so　as；　within　moderate　limits；　to　allow　it　to　accommodate　itself　to　any　such　changes　in　regard　to　mutual　parallelism；　as　above　referred　to。　　In　other　cases；　I　employed　what　I　may　call　Rocking　centres；　on　which　the　Pedestal　or　〃Plumber　Block〃　rested；　and　thus　supplied　a　self…adjusting　means　for　obviating　the　evils　resulting　from　any　accidental　change　in　the　proper　relative　position　of　the　shaft　and　its　bearing。　　In　all　cases　in　which　I　introduced　this　arrangement；　the　results　were　most　satisfactory。

In　the　case　of　the　bearings　of　Blowing　Fans；　in　which　the　rate　of　rotation　is　naturally　excessive；　a　spherical　resting…place　for　the　bearings　enabled　them　to　keep　perfectly　cool　at　the　highest　speed。　This　was　also　the　case　in　the　driving　apparatus　for　machine　tools；　which　is　generally　fixed　at　a　considerable　height　above　the　machine。　These　spherical　or　self…adjusting　bearings　were　found　of　great　service。　The　apparatus；　being　generally　out　of　convenient　reach；　is　apt　to　get　out　of　order　unless　duly　attended　to。　　But；　whether　or　not；　the　saving　of　friction　is　in　itself　a　reason　for　the　adoption　of　such　bearings。　This　may　appear　a　trifling　technical　matter　of　detail；　but　its　great　practical　value　must　be　my　excuse　for　mentioning　it。


1838。　Invention　of　Safety　Foundry　Ladle。

The　safety　ladle　is　described　in　the　text；　p。　　202。


1838。　Invention　of　the　Steam　Ram

My　invention　was　made　at　this　early　date；　long　before　the　attack　by　the　steam…ram　Merrimac　upon　the　Cumberland；　and　other　ships；　in　Hampt