Complex sentence: When in Edinburgh he took an active interest in the affairs of Augustine Church, of which the Rev. W. Lindsay Alexander, D.D., was minister; and in Glasgow he also for long took an active part in the management of Trinity Congregational Church.
Split into simpler sentences: When in Edinburgh he took an active interest in the affairs of the Augustine Church, of which the Rev. William Lindsay Alexander was minister. In Glasgow he also took an active part in the management of Trinity Congregational Church.