When brothers Ethan and Hosea Grosh left Pennsylvania in 1849, they joined throngs of men from all over the world intent on finding a fortune in the California Gold Rush. Their search for wealth took them from San Francisco into the gold country and then over the Sierra into Nevada's Gold Canyon, where they placer-mined for gold and discovered a deposit of silver. The letters they sent back to their family offer vivid commentaries on the turbulent...