Hi Margaret,
I have looked at the online immigrations, there is no Cavill's mentioned on them.
Victorian http://proarchives.imagineering.com.au/default.htm
NSW http://www.records.nsw.gov.au/staterecords/welcome_to_state_...
Have found the following, which Elle has posted
http://www.adb.online.anu.edu.au/biogs/A070601b.htm

http://www.waverley.nsw.gov.au/library/localstudies/walks/cm...
10. FREDERICK CAVILL (1839-1927) swimmer & teacher.

"The Professor of Swimming", operated baths at Lavender Bay, Farm Cove. Professional long distance swimmer, including 2 attempts of the English Channel.

http://www.athletic-scholarships.net/history-swimming.htm
NSW BDM
http://www.bdm.nsw.gov.au/familyHistory/search.htm
Death
2354/1927 CAVILL FREDERICK JOHN ISABELLA MARRICKVILLE

9111/1935 CAVILL ERNEST C FREDERICK THEOPHILE M BALMAIN
9999/1938 CAVILL RICHMOND THEOPHILUS FREDERICK MARY MOSMAN
1837/1880 CAVILL WALTER H FRANCIS W HANNAH R SYDNEY
1244/1879 CAVILL JANE L FRANCIS W HANNAH R SYDNEY
4926/1882 CAVILL UNNAMED FREDERICK THEOPHILA M ST LEONARDS

Births
8651/1881 CAVILL UNNAMED FREDERICK THEOPHILA MAY ST LEONARDS
9371/1882 CAVILL UNNAMED FREDERICK THEOPHILE M R ST LEONARDS
11396/1884 CAVILL RICHMOND T FREDERICK THEOPHILA M ST LEONARDS
Regards,
Lynne