He retired from NYU in 1978,[1] but continued as Professor Emeritus, lecturing on Avestan, Old Irish, Gothic, Hittite, and other languages, until the 1990s.
During World War II he supervised technical research in German, Dutch, Danish, Swedish, Norwegian, French, Spanish, Portuguese, Russian, and Japanese.
Later, at NYU he taught Yiddish, Gothic, Old Saxon, Frisian, Old Norse, Scandinavian, Sanskrit as well as German.
Fowkes was president[2] of the Linguistic Circle of New York, where he was one of the first members, along with Roman Jakobson and Morris Swadesh.
At the time of his death[3] (he was struck by a car while crossing a street in Yonkers, New York) he was working on a 30-year-long project to compile the first etymological dictionary of Welsh.