Complex sentence: He was a compositor and a proofreader for the "New York Times" from 1855 to 1859, and later worked for John W. Forney in Philadelphia at the "Press", and in Washington, D.C. for the "Sunday Morning Chronicle".
Split into simpler sentences: He was a compositor and a proofreader for the New York Times from 1855 to 1859. At the end of this term he employed his services to John W. Forney in Philadelphia for the "Press" and in Washington D.C. for the "Sunday Morning Chronicle".