Hello Eileen
Have just googled "george scammel manns" and have found a few snippets of info.
Google books "George Scammel Manns was in the British Army during the Indian Mutiny, and eventually rose to the rank of Colonel. He married in India in 1864, and came to Melbourne in 1865...."
He was fourth Australian fellow of the Theosophical Society and Secretary of the Democratic Society of Victoria
Marriage notice in the Argus (Melbourne, Victoria) on 24 Sep 1898
MANNS/BOWLEY
on the 30th August, at residence of the bride's sister, (Mrs Edmond Cooke. Segrif, Balwyn) by Rev J J Watsford, Ernest, eldest son of George Scammel Manns Esq of Wodonga, to Elizabeth, youngest daughter of William Bowley, JP, Auburn
death notice in the Argus 15 October 1910
MANNS on the 6th October at "NEWINGTON" Leneva, residence of her son-in-law, Jane, relict of late Colonel GS Manns, and beloved mother of EWM, FW and RB
death notice in the Argus 11 Oct 1902
MANNS - on 23rd September at Wodonga, Sydney Carton, dearly loved second son of George S and Jane Manns, aged 34 years
death notice in the Argus 22 February 1908
MANNS - on the 17th February, at Wodonga, Colonel George Scammel Manns, JP, (veteran of Indian mutiny) dearly loved husband of Jane Manns, and beloved father of Mrs E B Williams, Rose Manns, late Sidney Manns, and E W Manns, Canterbury
1868 - advertisements in the Argus show a GS Manns as Principal of Carlton House School, St Kilda
Seems the Jeddo was a mail steamer belonging to the Peninsular & Oriental Company
Have a play on the Australian Newspaper archives website:
http://trove.nla.gov.au/Good luck with your search, Dazey