decline of science in england-第21章

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he　adjustment；　and　repeat　the　process　fifty　or　a　hundred　times。　　This　will　not　merely　afford　him　excellent　practice；　but　enable　him　to　judge　of　his　own　skill。

The　first　step　in　the　use　of　every　instrument；　is　to　find　the　limits　within　which　its　employer　can　measure　the　SAME　OBJECT　UNDER　THE　SAME　CIRCUMSTANCES。　　It　is　only　from　a　knowledge　of　this；　that　he　can　have　confidence　in　his　measures　of　the　SAME　OBJECT　UNDER　DIFFERENT　CIRCUMSTANCES；　and　after　that；　of　DIFFERENT　OBJECTS　UNDER　DIFFERENT　CIRCUMSTANCES。

These　principles　are　applicable　to　almost　all　instruments。　　If　a　person　is　desirous　of　ascertaining　heights　by　a　mountain　barometer；　let　him　begin　by　adjusting　the　instrument　in　his　own　study；　and　having　made　the　upper　contact；　let　him　write　down　the　reading　of　the　vernier；　and　then　let　him　derange　the　UPPER　adjustment　ONLY；　re…adjust；　and　repeat　the　reading。　　When　he　is　satisfied　about　the　limits　within　which　he　can　make　that　adjustment；　let　him　do　the　same　repeatedly　with　the　lower；　but　let　him　not；　until　he　knows　his　own　errors　in　reading　and　adjusting；　pronounce　upon　those　of　the　instrument。　　In　the　case　of　a　barometer；　he　must　also　be　assured；　that　the　temperature　of　the　mercury　does　not　change　during　the　interval。

A　friend　once　brought　to　me　a　beautifully　constructed　piece　of　mechanism；　for　marking　minute　portions　of　time；　the　three…　hundredth　parts　of　a　second　were　indicated　by　it。　　It　was　a　kind　of　watch；　with　a　pin　for　stopping　one　of　the　hands。　I　proposed　that　we　should　each　endeavour　to　stop　it　twenty　times　in　succession；　at　the　same　point。　　We　were　both　equally　unpractised；　and　our　first　endeavours　showed　that　we　could　not　be　confident　of　the　twentieth　part　of　a　second。　In　fact；　both　the　time　occupied　in　causing　the　extremities　of　the　fingers　to　obey　the　volition；　as　well　as　the　time　employed　in　compressing　the　flesh　before　the　fingers　acted　on　the　stop；　appeared　to　influence　the　accuracy　of　our　observations。　From　some　few　experiments　I　made；　I　thought　I　perceived　that　the　rapidity　of　the　transmission　of　the　effects　of　the　will；　depended　on　the　state　of　fatigue　or　health　of　the　body。　If　any　one　were　to　make　experiments　on　this　subject；　it　might　be　interesting；　to　compare　the　rapidity　of　the　transmission　of　volition　in　different　persons；　with　the　time　occupied　in　obliterating　an　impression　made　on　one　of　the　senses　of　the　same　persons。　　For　example；　by　having　a　mechanism　to　make　a　piece　of　ignited　charcoal　revolve　with　different　degrees　of　velocity；　some　persons　will　perceive　a　continuous　circle　of　light　before　others；　whose　retina　does　not　retain　so　long　impressions　that　are　made　upon　it。


SECTION　3。

ON　THE　FRAUDS　OF　OBSERVERS。

Scientific　inquiries　are　more　exposed　than　most　others　to　the　inroads　of　pretenders；　and　I　feel　that　I　shall　deserve　the　thanks　of　all　who　really　value　truth；　by　stating　some　of　the　methods　of　deceiving　practised　by　unworthy　claimants　for　its　honours；　whilst　the　mere　circumstance　of　their　arts　being　known　may　deter　future　offenders。

There　are　several　species　of　impositions　that　have　been　practised　in　science；　which　are　but　little　known；　except　to　the　initiated；　and　which　it　may　perhaps　be　possible　to　render　quite　intelligible　to　ordinary　understandings。　　These　may　be　classed　under　the　heads　of　hoaxing；　forging；　trimming；　and　cooking。

OF　HOAXING。　　This；　perhaps；　will　be　better　explained　by　an　example。　　In　the　year　1788；　M。　Gioeni；　a　knight　of　Malta；　published　at　Naples　an　account　of　a　new　family　of　Testacea；　of　which　he　described；　with　great　minuteness；　one　species；　the　specific　name　of　which　has　been　taken　from　its　habitat；　and　the　generic　he　took　from　his　own　family；　calling　it　Gioenia　Sicula。　It　consisted　of　two　rounded　triangular　valves；　united　by　the　body　of　the　animal　to　a　smaller　valve　in　front。　　He　gave　figures　of　the　animal；　and　of　its　parts；　described　its　structure；　its　mode　of　advancing　along　the　sand；　the　figure　of　the　tract　it　left；　and　estimated　the　velocity　of　its　course　at　about　two…thirds　of　an　inch　per　minute。　　He　then　described　the　structure　of　the　shell；　which　he　treated　with　nitric　acid；　and　found　it　approach　nearer　to　the　nature　of　bone　than　any　other　shell。

The　editors　of　the　ENCYCLOPEDIE　METHODIQUE；　have　copied　this　description；　and　have　given　figures　of　the　Gioenia　Sicula。　　The　fact；　however；　is；　that　no　such　animal　exists；　but　that　the　knight　of　Malta；　finding　on　the　Sicilian　shores　the　three　internal　bones　of　one　of　the　species　of　Bulla；　of　which　some　are　found　on　the　south…western　coast　of　England；　＇Bulla　lignaria＇　described　and　figured　these　bones　most　accurately；　and　drew　the　whole　of　the　rest　of　the　description　from　the　stores　of　his　own　imagination。

Such　frauds　are　far　from　justifiable；　the　only　excuse　which　has　been　made　for　them　is；　when　they　have　been　practised　on　scientific　academies　which　had　reached　the　period　of　dotage。　　It　should　however　be　remembered；　that　the　productions　of　nature　are　so　various；　that　mere　strangeness　is　very　far　from　sufficient　to　render　doubtful　the　existence　of　any　creature　for　which　there　is　evidence；　　＇The　number　of　vertebrae　in　the　neck　of　the　plesiosaurus　is　a　strange　but　ascertained　fact＇　and　that；　unless　the　memoir　itself　involves　principles　so　contradictory；　as　to　outweigh　the　evidence　of　a　single　witness；　　＇The　kind　of　contradiction　which　is　here　alluded　to；　is　that　which　arises　from　well　ascertained　final　causes；　for　instance；　the　ruminating　stomach　of　the　hoofed　animals；　is　in　no　case　combined　with　the　claw…shaped　form　of　the　extremities；　frequent　in　many　of　the　carniverous　animals；　and　necessary　to　some　of　them　for　the　purpose　of　seizing　their　prey＇　it　can　only　be　regarded　as　a　deception；　without　the　accompaniment　of　wit。

FORGING　differs　from　hoaxing；　inasmuch　as　in　the　latter　the　deceit　is　intended　to　last　for　a　time；　and　then　be　discovered；　to　the　ridicule　of　those　who　have　credited　it；　whereas　the　forger　is　one　who；　wishing　to　acquire　a　reputation　for　science；　records　observations　which　he　has　never　made。　　This　is　sometimes　accomplished　in　astronomical　observations　by　calculating　the　time　and　circumstances　of　the　phenomenon　from　tables。　The　observations　of　the　second　comet　of　1784；　which　was　only　seen　by　the　Chevalier　D'Angos；　were　long　suspected　to　be　a　forgery；　and　were　at　length　proved　to　be　so　by　the　calculations　and　reasonings　of　Encke。　　The　pretended　observations　did　not　accord　amongst　each　other　in　giving　any　possible　orbit。　　But　M。　Encke　detected　an　orbit；　belonging　to　some　of　the　observations；　from　which　he　found　that　all　the　rest　might　be　almost　precisely　deduced；　provided　a　mistake　of　a　unity　in　the　index　of　the　logarithm　of　the　radius　vector　were　supposed　to　have　been　made　in　all　the　rest　of　the　calculations。　　ZACH。　CORR。　ASTRON。　Tom。　IV。　p。　456。

Fortunately　instances　of　the　occurrence　of　forging　are　rare。

TRIMMING　consists　in　clipping　off　little　bits　here　and　there　from　those　observations　which　differ　most　in　excess　from　the　mean；　and　in　sticking　them　on　to　those　which　are　too　small；　a　species　of　〃equitable　adjustment；〃　as　a　radical　would　term　it；　which　cannot　be　admitted　in　science。

This　fraud　is　not　perhaps　so　injurious　（except　to　the　character　of　the　trimmer）　as　cooking；　which　the　next　paragraph　will　teach；　The　reason　of　this　is；　that　the　AVERAGE　given　by　the　observations　of　the　trimmer　is　the　same；　whether　they　are　trimmed　or　untrimmed。　　His　object　is　to　gain　a　reputation　for　extreme　accuracy　in　making　observations；　but　from　respect　for　truth；　or　from　a　prudent　foresight；　he　does　not　distort　the　position　of　the　fact　he　gets　from　nature；　and　it　is　usually　difficult　to　detect　him。　　He　has　more　sense　or　less　adventure　than　the　Cook。

OF　COOKING。　　This　is　an　art　of　various　forms；　the　object　of　which　is　to　give　to　ordinary　observations　the　appearance　and　character　of　those　of　the　highest　degree　of　accuracy。

One　of　its　numerous　processes　is　to　make　multitudes　of　observations；　and　out　of　these　to　select　those　only　which　agree；　or　very　nearly　agree。　　If　a　hundred　observations　are　made；　the　cook　must　be　very　unlucky　if　he　cannot　pick　out　fifteen　or　twenty　which　will　do　for　serving　up。

Another　approved　receipt；　when　the　observations　to　be　used　will　not　come　within　the　limit　of　accuracy；　which　it　has　been　resolved　they　shall　possess；　is　to　calculate　them　by　two　different　formulae。　　The　difference　in　the　constants　employed　in　those　formulae　has　sometimes　a　most　happy　effect　in　promoting　unanimity　amongst　discordant　measures。　　If　still　greater　accuracy　is　required；　three　or　more　formulae　can　be　used。

It　must　be　admitted　that　this　receipt　is　in　some　instances　rather　hazardous：　　but　in　cases　where　the　positions　of　stars；　as　given　in　different　catalogues；　occur；　or　different　tables　of　specific　gravities；　specific　heats；　&c。　&c。；　it　may　safely　be　employed。　As　no　catalogue　contains　all　stars；　the　computer　must　have　recourse　to　several；　and　if　he　is　obliged　to　use　his　judgment　in　the　selection；　it　would　be　cruel　to　deny　him　any　little　advantage　which　might　result　from　it。　　It　may；　however；　be　necessary　to　guard　against　one　mistake　into　which　persons　might　fall。

If　an　observer　calculate　particular　stars　from　a　catalogue　which　makes　them　accord　precisely　with　the　rest　of　his　results；　whereas；　had　they　been　computed　from　other　catalogues　the　difference　would　have　been　considerable；　it　is　very　unfair　to　accuse　him　of　COOKING；　forthose　catalogues　may　have　been　notoriously　inaccurate；　orthey　may　have　been　superseded　by　others　more　recent；　or　made　with　better　instruments；　orthe　observer　may　have　been　totally　ignorant　of　their　existence。

It　sometimes　happens　that　the　constant　quantities　in　formulae　given　by　the　highest　authorities；　although　they　differ　amongst　themselves；　yet　they　will　not　suit　the　materials。　　This　is　precisely　the　point　in　which　the　skill　of　the　artist　is　shown；　and　an　accomplished　cook　will　carry　himself　triumphantly　through　it；　provided　happily　some　mean　value　of　such　constants　will　fit　his　observations。　　He　will　discuss　the　relative　merits　of　formulae　he　has　just　knowledge　enough　to　use；　and；　with　admirable　candour　assigning　their　proper　share　of　applause　to　Bessel；　to　Gauss；　and　to　Laplace；　he　will　take　THAT　mean　value　of　the　constant　used　by　three　such　philosophers；　which　will　make　his　own　observations　accord　to　a　miracle。

There　are　some　few　reflections　which　I　would　venture　to　suggest　to　those　who　cook；　although　they　may　perhaps　not　receive　the　attention　which；　in　my　opinion；　they　deserve；　from　not　coming　from　the　pen　of　an　adept。

In　the　first　place；　it　must　require　much　time　to　try　different　formulae。　　In　the　next　place　it　may　happen　that；　in　the　progress　of　human　knowledge；　more　correct　formula：　　may　be　discovered；　and　constants　may　be　determined　with　far　greater　precision。　　Or　it　may　be　found　that　some　physical　circumstance　influences　the　results；　（although　unsuspected　at　the　time）　the　measure　of　which　circumstance　may　perhaps　be　recovered　from　other　contemporary　registers　of　facts。　　＇Imagine；　by　way　of　example；　the　state　of　the　barometer　or　thermometer。＇　　Or　if　the　selection　of　observations　has　been　made　with　the　view　of　its　agreeing　precisely　with　the　latest　determination；　there　is　some　little　danger　that　the　average　of　the　whole　may　differ　from　that　o