In the summers of 1913 and 1914, he visited his brother, who taught history and religious education at the University of Nanking and became intrigued with the country from which Japan had learned so much.

[1] He returned to the United States in 1914, married, and in November the couple went to China as missionaries of the American Board of Commissioners for Foreign Missions.

Graves and Hummel worked not only to build the Library of Congress collection but to promote the study of Asia in colleges and universities across the country.

Hummel did so, and his dissertation, The Autobiography of a Chinese Historian earned him the PhD degree from the University of Leiden on September 23, 1931.

[1][3] Graves arranged funding for Hummel's work on the Eminent Chinese of the Ch'ing Period, which began in 1934 and was published by the United States Government Printing Office in 1943.