The grandson of the 10th President of the United States, John Tyler, has died at 96 — 180 years after his grandfather was last in the White House.Harrison Ruffin Tyler, the son of President Tyler’s 13th child, Lyon Gardiner Tyler, died on Sunday evening at a Virginia nursing home, ending the last living link to an 18th-century presidential administration.When he was born on Nov. 9, 1928, his father was 75 years old.