Fort Worth, Texas, is now the first city government in the United States to mine bitcoin — and in an almost poetic devotion to the initiative, Mayor Mattie Parker oversaw the construction of a small mining farm in City Hall. Three Bitmain Antminer S9 mining rigs will run 24 hours a day, seven days a week, in the climate-controlled information technology wing of Fort Worth City Hall. The city says the miners will be hosted on a private network to minimize the security risk. Bitcoin operates on a proof-of-work mining model, meaning that miners around the world run high-powered computers...