Ancestry has a tree with him in it -from what I can see it appears to be well-researched with certificates etc mentioned. You should check though.
His parents are listed as
William HAMMER, b Apr 1846, St Austell, Cornwall, England, died 2 NOV 1896 • Ballarat East,
and
Elizabeth Jane TRELOAR, b Dec 1851, Cornwall, England, died 1927. Ballarat East, Victoria, Australis
Judith