Complex sentence: Mary Margaret O'Reilly (October 14,1865--December 6,1949) was the Assistant Director of the United States Bureau of the Mint for the Mint for 34 years, from 1904 to her retirement in 1938.
Split into simpler sentences: Mary Margaret O'Reilly (October 14,1865--December 6,1949) was the Assistant Director of the United States Bureau of the Mint. She worked for the Mint for 34 years, from 1904 to her retirement in 1938.