Complex sentence: E. G. Paley, then aged 15, joined Sharpe as a pupil in 1838, and seven years later became a partner in the practice, which adopted the name of Sharpe and Paley.
Split into simpler sentences: E. G. Paley, then aged 15, joined Sharpe as a pupil in 1838. Seven years later he became a partner in the practice, which adopted the name of Sharpe and Paley.