Complex sentence: He was elected to the Society of Arts, founded by his friend William Shipley in the 1760s and played an active part, introducing many other members and acting as chairman of the Committee of Mechanics for many years.
Split into simpler sentences: He was elected to the Society of Arts which was founded by his friend William Shipley in the 1760s. He introduced other members and he was the active chairman of the Committee of Mechanics for many years.