In June 1840 he left Sydney on the Bright Planet for Port Phillip to investigate commercial possibilities in the newly founded town of Melbourne.
Cashmore married Elizabeth "Betsy" Solomon (1821–1898) in Sydney on 9 December 1840, and later that month boarded the PS Clonmel, bound for Port Phillip.
[1] He, in partnership with Samuel Emmanuel, opened a shop in the first brick building in Melbourne, owned by Alexander Brunton on Elizabeth Street, on the north-east corner of the Collins intersection.
In February 1886 he was compelled to cease work due to ill health, and was granted leave with full pay for twelve months.
He was connected with a number of societies and charitable institutions, and a longtime member and past master of the Lodge Of Australia Felix (founded 1839 in Melbourne).