An Irish New Yorker, he immigrated to San Francisco in 1849 and opened up a saloon with William S. O'Brien. Hearing mining tips in the bar lead them to stock brokerage speculation. They ended up controlling Nevada silver mines at the time of the big bonanza, thus his nickname "Bonanza Jim". Four years after quitting the saloon business these two men had an income of $500,000 per month in 1853. He built an estate in Atherton and a large city home on Nob Hill (now the Pacific Union Club).