I'm trying to find the place of origin for my g-g-grandmother Maria (or Ann Mary) Baumann who emigrated from Germany eventually to Australia via the UK in 1857. I have her journey from Liverpool to Australia in 1857, and I have two possibles for her initial journey from (probably) Rotterdam to London which, if correct, suggest she would have been in the UK for between 17 months and 4 years. Neither gives a place of origin. One however was on the Batavier, a Rotterdam-registered steamship, arranged by the Mainz-based agent Carl Ahlborn. The other just gives Rotterdam-London and a date, no ship's name.
Any advice on where to turn next would be gratefully received.