Complex sentence: He was educated at Dr. Burnet's school in Hackney and trained as an architect under his father, but two childhood accidents damaged his health, and he did not set himself up in practice himself until 1842.
Split into simpler sentences: He was educated at Dr. Burnet's school in Hackney. He trained as an architect under his father, but two childhood accidents damaged his health, and he did not set himself up as an architect until 1842.