icate ▁methods ▁and ▁instruments , ▁including ▁his ▁electric ▁compens ation ▁p yr hel i ometer , ▁invent ed ▁in ▁ 1 8 9 3 , ▁appar atus ▁for ▁obtain ing ▁a ▁phot ographic ▁representation ▁of ▁the ▁inf ra - red ▁spectrum ▁( 1 8 9 5 ) ▁and ▁p yr ge ometer ▁( ab t . ▁ 1 9 0 5 ). ▁ ▁In ▁ 1 9 0 0 , ▁Herr ▁J . ▁Koch , ▁labor atory ▁assistant ▁to ▁Kn ut ▁ ▁Å ng ström , ▁did ▁not ▁observe ▁any ▁appreci able ▁change ▁in ▁the ▁absor ption ▁of ▁inf ra red ▁radiation ▁by ▁decre asing ▁the ▁concentration ▁of ▁CO 2 ▁up ▁to ▁a ▁third ▁of ▁the ▁initial ▁amount . ▁This ▁ ▁result , ▁in ▁addition ▁to ▁the ▁observation ▁made ▁a ▁couple ▁of ▁years ▁before ▁that ▁the ▁super position ▁of ▁the ▁water ▁v ap our ▁absor ption ▁bands , ▁more ▁abund ant ▁in ▁the ▁atmosphere , ▁over ▁those ▁of ▁CO 2 , ▁convinced ▁some ▁ge olog ists ▁for ▁a ▁time ▁that ▁calculations ▁by ▁Sv ante ▁Arr hen ius ▁for ▁CO 2 ▁war ming ▁were ▁wrong ; ▁though ▁subsequent ▁work ▁in ▁following ▁dec ades ▁eventually ▁v ind ic ated ▁Arr hen ius . ▁▁ ▁The ▁experiment , ▁however , ▁was ▁care less ▁seen ▁from ▁the ▁current ▁perspective ▁with ▁err one ous ▁result ▁but ▁of ▁a ▁historical ▁significance ▁in ▁the ▁development ▁of ▁the ▁theory ▁of ▁the ▁green house ▁effect ▁ampl ified ▁by ▁CO 2 . ▁ ▁He ▁was ▁elected ▁a ▁member ▁of ▁the ▁Royal ▁Swedish ▁Academy