Complex sentence: The devices were in use by the late 19th century, including an early Australian system at Mount Crosby, Queensland in which an extension bell was situated was connected to an engineer's telephone at a distance of a quarter mile.
Split into simpler sentences: The devices were in use by the late 19th century. An early Australian system at Mount Crosby, Queensland featured an extension bell which was connected to an engineer's telephone over a distance of a quarter mile.