While in Cape Town, he corresponded with the doyen of American anthropology Franz Boas at Columbia, who secured him a grant of 2000 dollars to undertake field work on the Maidu language under the auspices of the Archaeological and Ethnographic Survey of California, established by A. L. Kroeber in 1901.
Discarding the idea of working on languages of the New Guinea or Southeast Asia, colleagues suggested that he study the Danish dialect of Rovsø in Jutland.
He worked there in the village of Udby for a year before his wife fell ill and the two had to leave the town collecting documentation and making detailed transcriptions of the local dialect, which came to form part of the Danish dialectological corpus after his death.
From 1939 to 1948 he worked for the British Council in locations such as Athens, Baghdad, Cairo and Alexandria, and after the war in Paraguay and Argentina, where he was appointed professor at the National University of Tucumán.
Uldall, writing separately on his part of the work, had drifted away from Hjelmslevs idea on several points, and when he finished his Outline of Glossematics, a Study in the Methodology of the Humanities with Special Reference to Linguistics.