Theintroductionofironasthematerialforshipbuildinghasimmenselyadvancedtheinterestsofsteamnavigation，asitenablesthebuilderstoconstructvesselsofgreatsizewiththefinestlines，soastoattainthehighestratesofspeed。
OnemighthavesupposedthatFrancisPettitSmithwouldderivesomesubstantialbenefitfromhisinvention，oratleastthattheShipPropellerCompanywoulddistributelargedividendsamongtheirproprietors。Nothingofthekind。Smithspenthismoney，hislabour，andhisingenuityinconferringagreatpublicbenefitwithoutreceivinganyadequatereward；andthecompany，insteadofdistributingdividends，lostabout50，000L。inintroducingthisgreatinvention；afterwhich，in1856，thepatent-rightexpired。Threehundredandtwenty-sevenshipsandvesselsofallclassesintheRoyalNavyhadthenbeenfittedwiththescrewpropeller，andamuchlargernumberinthemerchantservice；butsincethattimethenumberofscrewpropellersconstructedistobecountedbythousands。
Inhiscomparativelyimpoverishedconditionitwasfoundnecessarytodosomethingfortheinventor。TheCivilEngineers，withRobertStephenson，M。P。，inthechair，entertainedhimatadinnerandpresentedhimwithahandsomesalverandclaretjug。
Andthathemighthavesomethingtoputuponhissalverandintohisclaretjug，anumberofhisfriendsandadmirerssubscribedover2000L。asatestimonial。TheGovernmentappointedhimCuratorofthePatentMuseumatSouthKensington；theQueengrantedhimapensionontheCivilListfor200L。ayear；hewasraisedtothehonourofknighthoodinl87l，andthreeyearslaterhedied。
FrancisPettitSmithwasnotagreatinventor。Hehad，likemanyothers，inventedascrewpropeller。But，whilethoseothershadgivenuptheideaofprosecutingittoitscompletion，Smithstucktohisinventionwithdeterminedtenacity，andneverletitgountilhehadsecuredforitacompletetriumph。AsMr。