Cika wannan jumla: A shekara ta 1920 an nada shi darektan Allegheny Observatory. A cikin wannan shekarar ya shiga cikin
Babban muhawara tare da Harlow Shapley (wanda ake kira Shapley <unk> Curtis Debate) akan yanayin nebulae da taurari, da girman sararin samaniya. Curtis ya goyi bayan ra'ayin da aka yarda da shi yanzu cewa akwai wasu taurari banda Milky Way.