There is a very interesting book on that expedition - The Voyage of the Herman; The Dramatic Story of the Search for the $100 Million Treasure of Lima by Theon Wright and Ione Ulrich Sutton (1966). I highly recommend it - it's quite a yarn. It would have been an even better book if the authors had found a copy of the extremely rare Our Search for the Missing Millions by "One of the Searchers" (South Sea Bubble Publishing Company, San Francisco: 1904).
Robert Nesmith does a fine job of telling the Cocos Island story in his classic Dig for Pirate Treasure (1958).
If you've read Richard Knight's Treasure; The True Story of His Extraordinary Quest for Captain kidd's Cache by Glenys Roberts (1987) you'll see some solid parallels between Captain Brown and Mr. Knight. Although Mr. Knight certainly lacked Capt. Brown's menace.
Good luck to all,
The Old Bookaroo
