I believe that Richard Brown of the 1850 Burlington, Racine, WI census (enumerated 15 October 1850) is the same Richard Brown who arrived in San Francisco on the SS Sarah Sands 17 December 1850. I think he went down the Mississippi to New Orleans and took a ship to Panama where he got on the Sarah Sands. How can I know for sure?
Olive Tree Answer: Hello Beth: Comparing the 1850 Wisconsin census and the 1860 Mendocino census on Ancestry.com, it is very probable that this is the same Richard and Margaret J. Brown.
However, you need a few more facts to establish certainty, and you are a long way from proof that Richard was on that 1850 ship. If you look at the passenger list, the comment reads "25 days from Panama, via Acapulco Mexico; 12 days, Dec 17, 1850. " It is possible that Richard could have travelled from Wisconsin to Mexico or Panama in a little over a month. But is it probable?
As there are little or no intra-US passenger lists, you may have to rely on newspaper articles (in Wisconsin and California, as well as in Gulf port cities.) Did Richard appear in any items such as "In the Hotels" or "In Transit" or other announcements? You can check newspapers online at GenealogyBank.com or
Check the real estate transactions in California: when is Richard first mentioned?
I see that Richard died in July of 1860, and Margaret in November of 1870: check for obituaries. And be sure to check in Wisconsin as well.
If you are sure, or family lore has it that Richard was a gold miner, there are many books from that period: diaries, store ledgers, county histories.