Complex sentence: At sixteen he began supporting himself by teaching in public schools, but his health failed, and in 1842, he "drifted" to Boston where he edited the "Social Monitor and Orphan's Advocate" and began working in a law office.
Split into simpler sentences: At sixteen he began supporting himself by teaching in public schools, but his health failed. In 1842, he "drifted to Boston" where he edited the "Social Monitor and Orphan's Advocate" and began working in a law office.