Complex sentence: He began to study in London for the medical profession, but ill-health caused him to return to the west of England, and in 1840 he became secretary to the Royal Cornwall Polytechnic Society at Falmouth.
Split into simpler sentences: He began to study in London for the medical profession, but ill-health caused him to return to the west of England. In 1840 he became secretary to the Royal Cornwall Polytechnic Society at Falmouth.