I was previously unaware that Herbert Hoover had an interest in an Australian gold mine! I thought he just built dams and stuff.
If Chaffey brothers had come later I would have guessed that they were somehow a product of the Prohibition era. They might have been Quakers. There's a dry town just down the round from here named Friendswood. It was founded by Quakers and is now actually a rather sizeable city, one of the mid-scale NASA bedroom communities. There's not a single bar or liquor store within the city limits.
What was the Eureka Stockade about?