hɪz ˈɜːli kɚɹˈɪɹ wʌz spˈɛnt ˌɔn sˈoʊlɚ stˈʌdiz, ɪŋklˈuːdɪŋ ɑːbzɚvˈeɪʃənz ʌv sˈʌnspɑːts ænd dˌɛɹɪvˈeɪʃənz ʌvðə ɹoʊtˈeɪʃən pˈiəɹɪəd.
His early career was spent on solar studies, including observations of sunspots and derivations of the rotation period.