TheverynextyearafterDr。Wells’spaperwaspublishedthereappearedinFrancethethirdvolumeoftheMemoiresdePhysiqueetdeChimiedelaSocieted’Arcueil，andanewepochinmeteorologywasinaugurated。
Thesocietyinquestionwasnumericallyaninconsequentialband，listingonlyadozenmembers；buteverynamewasafamousone:Arago，Berard，Berthollet，Biot，Chaptal，DeCandolle，Dulong，Gay-Lussac，Humboldt，Laplace，Poisson，andThenard——rarespiritseveryone。Littledangerthatthememoirsofsuchabandwouldberelegatedtothedustyshelveswheremostproceedingsofsocietiesbelong——nomilk-for-babesfarewouldbeservedtosuchacompany。
Theparticularpaperwhichhereinterestsusclosesthisthirdandlastvolumeofmemoirs。Itisentitled\"DesLignesIsothermesetdelaDistributiondelaChaleursurleGlobe。\"TheauthorisAlexanderHumboldt。
Needlesstosay，thetopicishandledinamasterlymanner。Thedistributionofheatonthesurfaceoftheglobe，onthemountain-sides，intheinterioroftheearth；thecausesthatregulatesuchdistribution；theclimaticresults——thesearethetopicsdiscussed。Butwhatgivesepochalcharactertothepaperistheintroductionofthoseisothermallinescirclingtheearthinirregularcourse，joiningtogetherplaceshavingthesamemeanannualtemperature，andthuslayingthefoundationforascienceofcomparativeclimatology。
Itistruetheattempttostudyclimatescomparativelywasnotnew。Mairanhadattempteditinthosepapersinwhichhedevelopedhisbizarreideasastocentralemanationsofheat。Eulerhadbroughthisprofoundmathematicalgeniustobearonthetopic，evolvingthe\"extraordinaryconclusionthatundertheequatoratmidnightthecoldoughttobemorerigorousthanatthepolesinwinter。\"AndinparticularRichardKirwan，theEnglishchemist，hadcombinedthemathematicalandtheempiricalmethodsandcalculatedtemperaturesforalllatitudes。ButHumboldtdiffersfromallthesepredecessorsinthathegraspstheideathatthebasisofallsuchcomputationsshouldbenottheory，butfact。Hedrewhisisothermallinesnotwheresomeoccultcalculationwouldlocatethemonanidealglobe，butwherepracticaltestswiththethermometerlocatethemonourglobeasitis。London，forexample，liesinthesamelatitudeasthesouthernextremityofHudsonBay；buttheisothermofLondon，asHumboldtoutlinesit，passesthroughCincinnati。