Mauchly's easygoing nature provided a favorable foil to Eckert's high-strung personality. Eckert was always electrified with nervous energy, and while working on ENIAC was known to drop into the lab to check on one thing and end up staying the entire night tinkering and brainstorming improvements. He had a funny habit of carrying a pocket-watch chain with no watch attached, and twirling the chain continuously when he was aggravated or stressed by something.
In preparation for Medal Day ceremonies, The Franklin Institute wrote to Mauchly and Eckert inquiring after their respective marital statuses. Both men were married. Eckert met his wife, Hester Caldwell, on a train and through conversation learned that she was engaged to someone else. He later persuaded her to marry him instead!
Letter from Henry B. Allen to Dr. Mauchly, Inquires as to Mauchly's title and marital status. (750k). 7/11/1949
Letter from Henry B. Allen to Mr. Eckert, Inquires as to Eckert's title and marital status. (875k). 7/11/1949
Letter from Dr. Mauchly to Henry B. Allen, Response to inquire about title and marital status. (706k). 7/14/1949