 Jefferson used a polygraph device that enabled him to make the copy at the same time that he was writing the original.An Englishman, John Isaac Hawkins, and an American, Charles Willson Peale, had earlier developed this device with the help of Jefferson's suggestions.In 1987, a member of the Ellicott family, which had retained Banneker's only remaining journal, donated that document and other Banneker manuscripts to the Maryland Historical Society in Baltimore.