which person is the only man to both take and administer the oath of office
One man has both taken and administered the oath of office.
Twelve years after he was sworn in as America’s 27th president, William Howard Taft was appointed chief justice of the Supreme Court. In that role, he was the man to administer the oaths of office to Calvin Coolidge in 1925 and Herbert Hoover in 1929.
William Howard Taft (September 15, 1857 – March 8, 1930) served as the 27th President of the United States (1909–1913) and as the 10th Chief Justice of the United States (1921–1930), the only person to have held both offices. Taft was elected president in 1908, the chosen successor of Theodore Roosevelt, but was defeated for re-election by Woodrow Wilson in 1912 after Roosevelt split the Republican vote by running as a third-party candidate. In 1921, President Warren G. Harding appointed Taft to be chief justice, a position in which he served until a month before his death.
3rd Coolidge Oath of Office: The third time Coolidge took the oath of office was on March 4, 1925 after he had won election in his own right to the presidency. For the first time ever, the oath was administered by a former president, William Howard Taft, who was the Chief Justice of the Supreme Court.