an autobiography-第79部分

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　compartment　formed　by　the　space　between　the　ends　of　the　blades　of　the　Fan　shall　in　its　course　of　rotation　possess　an　equal　facility　of　exit　for　the　passage　of　the　air　it　is　discharging。　Thus；　in　a　Fan　with　six　blades；　the　space　between　the　top　of　the　blades　and　the　case　of　the　Fan　should　increase　in　area　in　the　progressive　ratios　of　1…2…3…4…5…6。

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If　a　Fan　be　constructed　on　this　common…sense　principle；　we　shall　secure　the　maximum　of　blast　from　the　minimum　of　driving　power。　　And　not　only　so；　but　the　humming　soundso　disagreeable　an　accompaniment　to　the　action　of　the　Fans　（being　caused　by　the　successive　sudden　escape　of　the　air　from　each　compartment　as　it　comes　opposite　the　space　where　it　can　discharge　its　confined　block　of　air）will　be　avoided。　　When　the　outer　case　of　a　Fan　is　formed　on　the　expanding　or　spiral　principle；　as　above　described；　all　these　important　advantages　will　attend　its　use。　As　the　inward　current　of　air　rushes　in　at　the　circular　openings　on　each　side　of　the　Fan…case；　and　would　thus　oppose　each　other　if　there　was　a　free　communication　between　them；　this　is　effectually　obviated　by　forming　the　rotating　portion　of　the　fan　by　a　disc　of　iron　plate；　which　prevents　the　opposite　in…rushing　currents　from　interfering　with　each　other；　and　at　the　same　time　supplies　a　most　substantial　means　of　fastening　the　blades；　as　they　are　conveniently　riveted　to　this　central　disc。　　On　the　whole；　this　arrangement　of　machinery　supplies　a　most　effective　〃Noiseless　Blowing　Fan。〃


1845。　A　direct　Action　〃Suction〃　Fan　for　the　Ventilation　of　Coal…Mines。

The　frequency　of　disastrous　colliery　explosions　induced　me　to　give　my　attention　to　an　improved　method　for　ventilating　coal　mines。　The　practice　then　was　to　employ　a　furnace；　placed　at　the　bottom　of　the　upcast　shaft　of　the　coal…pit；　to　produce　the　necessary　ventilation。　This　practice　was　highly　riskful。　　It　was　dangerous　as　well　as　ineffective。　　It　was　also　liable　to　total　destruction　when　an　explosion　occurred；　and　the　means　of　ventilation　were　thus　lost　when　it　was　most　urgently　required。　　The　ventilation　of　mines　by　a　current　of　air　forced　by　a　Fan　into　the　workings；　had　been　proposed　by　a　German　named　George　Agricola；　as　far　back　as　1621。　　The　arrangement　is　found　figured　in　his　work　entitled　De　Re　Metalicat；　p。　162。　　But　in　all　cases　in　which　this　system　of　forcing　air　through　the　workings　and　passages　of　a　mine　has　been　tried；　it　has　invariably　been　found　unsuccessful　as　a　means　of　ventilation。

As　all　rotative　Blowing　Fans　draw　in　the　air　at　their　centres；　and　expel　it　at　their　circumference；　it　occurred　to　me　that　if　we　were　to　make　a　communication　between　the　upcast　shaft　of　the　mine　and　the　centre　or　suctional　part　of　the　Fan　closing　the　top　of　the　upcast　shaft；　a　Fan　so　arranged　would　draw　out　the　foul　air　from　the　mine；　and　allow　the　fresh　air　to　descend　by　the　downcast　shaft；　and　so　traverse　the　workings。　　And　as　a　Suction　Fan　so　placed　would　be　on　the　surface　of　the　ground；　and　quite　out　of　the　way　of　any　risk　of　injurybeing　open　to　view　and　inspection　at　all　timeswe　should　thus　have　an　effective　and　trustworthy　means　for　thorough　ventilation。

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Having　communicated　the　design　for　my　Direct　Action　Suction　Fan　for　coal…pit　ventilation　to　the　Earl　Fitzwilliam；　through　his　agent　Mr。　Hartop；　in　1850；　his　lordship　was　so　much　pleased　with　it　that　I　received　an　order　for　one　of　14　feet　diameter；　for　the　purpose　of　ventilating；　one　of　his　largest　coalpits。　　I　arranged　the　steam…engine　which　gave　motion　to　the　large　Fan；　so　as　to　be　a　part　of　it；　and　by　placing　the　crank　of　the　engine　on　the　end　of　the　Fan…shaft；　the　engine　transferred　its　power　to　it　in　the　most　simple　and　direct　manner。　　The　high　satisfaction　which　this　Ventilating　Fan　gave　to　the　Earl　and　to　all　connected　with　his　coal…mines；　led　to　my　receiving　orders　for　several　of　them。

I　took　out　no　patent　for　the　invention；　but　sent　drawings　and　descriptions　to　all　whom　I　knew　to　be　interested　in　coalmine　ventilation。　I　read　a　paper　on　the　subject；　and　exhibited　the　necessary　drawings；　at　the　meeting　of　the　British　Association　at　Ipswich　in　1851。　　These　were　afterwards　published　in　the　Mining　Journal。　　The　consequence　is　that　many　of　my　Suction　Ventilating　Fans　are　now　in　successful　action　at　home　and　abroad。


1845。　An　improvement　in　the　Links　of　Chain　Cables。



1845。　An　Improved　Method　of　Welding　Iron。

One　of　the　most　important　processes　in　connection　with　the　production　of　the　details　of　machinery；　and　other　purposes　in　which　malleable　iron　is　employed；　is　that　termed　welding；　namely；　when　more　or　less　complex　forms　are；　so　to　speak；　〃built　up〃　by　the　union　of　suitable　portions　of　malleable　iron　united　and　incorporated　with　each　other　in　the　process　of　welding。　　This　consists　in　heating　the　parts　which　we　desire　to　unite　to　a　white　heat　in　a　smith's　forge　fire；　or　in　an　air　furnace；　by　means　of　which　that　peculiar　adhesive　〃wax…like〃　capability；　of　sticking　together　is　induced；so　that　when　the　several　parts　are　forcibly　pressed　into　close　contact　by　blows　of　a　hammer；　their　union　is　rendered　perfect。

But　as　the　intense　degree　of　heat　which　is　requisite　to　induce　this　adhesive　quality　is　accompanied　by　the　production　of　a　molten　oxide　of　iron　that　clings　tenaciously　to　the　white…hot　surfaces　of　the　iron；　the　union　will　not　be　complete　unless　every　particle　of　the　adhesing　molten　scoriae　is　thoroughly　discharged　and　driven　out　from　between　the　surfaces　we　desire　to　unite　by　welding。　　If　by　any　want　of　due　care　on　the　part　of　the　smith；　the　surfaces　be　concave　or　have　hollows　in　them；　the　scoriae　will　be　sure　to　lurk　in　the　recesses；　and　result　in　a　defective　welding　of　a　most　treacherous　nature。　　Though　the　exterior　may　display　no　evidence　of　the　existence　of　this　fertile　cause　of　failure；　yet　some　undue　or　unexpected　strain　will　rend　and　disclose　the　shut…up　scoriae；　and　probably　end　in　some　fatal　break…down。　　The　annexed　figures　will　perhaps　serve　to　render　my　remarks　on　this　truly　important　subject　more　clear　to　the　reader。

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Fig。1　represents　an　imperfectly　prepared　surface　of　two　pieces　of　malleable　iron　about　to　be　welded。　　The　result　of　their　concavity　of　form　is　that　the　scoriae　are　almost　certain　to　be　shut　up　in　the　hollow　part；as　the　pieces　will　unite　first　at　the　edges　and　thus　include　the　scoriae；　which　no　amount　of　subsequent　hammering　will　ever　dislodge。　　They　will　remain　lurking　between；　as　seen　in　Fig。2。　　Happily；　the　means　of　obviating　all　such　treacherous　risks　are　as　simple　as　they　are　thoroughly　effective。　　All　that　has　to　be　done　to　render　their　occurrence　next　to　impossible　is　to　give　to　the　surfaces　we　desire　to　unite　by　welding　a　convex　form　as　represented　in　Fig。　3；　the　result　of　which　is　that　we　thus　provide　an　open　door　for　the　scoriae　to　escape　from　between　the　surfaces；as　these　unite　first　in　the　centre；　as　due　to　the　convex　form；　and　then　the　union　proceeds　outwards；　until　every　particle　of　scoriae　is　expelled；　and　the　union　is　perfectly　completed　under　the　blows　of　the　hammer　or　other　compressing　agency。　Fig。　4　represents　the　final　and　perfect　completion　of　the　welding；　which　is　effected　by　this　common…sense　and　simple　means；that　is；　by　giving　the　surfaces　a　convex　form　instead　of　a　concave　one。

When　I　was　called　by　the　Lords　of　the　Admiralty　in　1846　to　serve　on　a　Committee；　the　object　of　which　was　to　investigate　the　causes　of　failure　in　the　wrought…iron　smith　work　of　the　navy；　many　sad　instances　came　before　us　of　accidents　which　had　been　caused　by　defective　welding；　especially　in　the　vitally　important　articles　of　Anchors　and　Chain　Cables。　In　the　case　of　the　occasional　failure　of　chain　cables；　the　cause　was　generally　assigned　to　defective　material；　but　circumstances　led　me　to　the　conclusion　that　it　was　a　question　of　workmanship　or　maltreatment　of　what　I　knew　to　be　of　excellent　material。　　I　therefore　instituted　a　series　of　experiments　which　yielded　conclusive　evidence　upon　the　subject；　and　which　proved　that　defective　welding　was　the　main　and　chief　cause　of　failure。　　In　order　to　prove　this；　several　apparently　excellent　cables　were；　by　the　aid　of　〃the　proving　machine；〃　pulled　to　pieces；　link　by　link；　and　a　careful　record　was　kept　of　the　nature　of　the　fracture。　　The　result　was；　that　out　of　every　100　links　pulled　asunder　80　cases　clearly　exhibited　defective　welding；　while　only　20　were　broken　through　the　clear　sound　metal。　　This　yielded　a　very　important　lesson　to　those　specially　concerned。


1845。　Introduction　of　the　V　Anvil。

In　connection　with　my　Steam　Hammer；　when　employed　in　forging　great　cylindrical　shafts；　I　introduced　what　I　termed　my　V　anvil。　Its　employment　has　most　importantly　contributed　to　secure　perfect　soundness　in　such　class　of　forgings。

In　the　old　system　of　forging　cylindrical　shafts；　the　bar　was　placed　upon　a　flat…faced　anvil。　　The　effect　of　each　blow　of　the　hammer　upon　the　work　was　to　knock　the　shaft　into　an　oval　form　（see　Fig。　1）；　and　the　inevitable　result　of　a　succession　of　such　blows　was　destruction　of　the　soundness　of　the　centre　or　axis　of　the　shaft。

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In　order　to　remedy　this　grave　defect；　arising　from　the　employment　of　a　flat…faced　anvil；　I　introduced　my　V　anvil　face　（see　Fig。　2）；　the　effect　of　which　was；　that　the　dispersive　action　of　the　blow　of　the　hammer　was　changed　into　a　converging　action；　which　ensured　the　perfect　soundness　of　the　work；　while　the　V　or　fork…like　form　of　the　angle　face　kept　the　work　steadily　under　the　centre　of　the　hammer；　allowing　the　scale　or　scoriae　to　fall　into　the　apex　or　bottom　of　the　V；　which　thus　passed　away；　leaving　the　faces　of　the　angle　quite　clear。

This　simple　and　common…sense　improvement　was　eagerly　and　generally　adopted；　and　has　been　productive　of　most　satisfactory　and　important　results。


1847。　A　Spherical…seated　Direct…weighted　Safety　Valve。

Having　been　on　several　occasions　called　to　investigate　the　causes　of　steam　boiler　explosions；　my　attention　was　naturally　directed　to　the　condition　of　the　Safety　Valve。　　I　found　the　construction　of　them　in　many　cases　to　be　defective　in　principle　as　well　as　in　mechanical　details；　resulting　chiefly　from　the　employment　of　a　conical　form　in　the　valve；　which　necessitated　the　use　of　a　guide　spindle　to　enable　it　to　keep　in　correct　relative　positio