You may find this page useful.http://www.adb.online.anu.edu.au/biogs/A120612b.htm
The travelling Wirth family : a history of our ancestors as musicians, miners and Wirths' Circus including descendants /researched and compiled by Gayle Speight ; with genealogical research by Gayle Speight, Stephanie Wirth and Margaret Wright.
The book tells the story of the Wirth family from their beginnings in Germany as villagers and travelling musicians to 2006. They came to Australia to search for gold and eventually became well-known circus people. Names associated with them are Darr, Walsh, Giles, Harth, Blinco, Kennedy, Christie, Morris, Liebke, Muller, Mutze and Northey. Research was also undertaken by Stephanier and Margaret Wright.