The United States and Canada run their grids at 60 hertz, and Britain, Europe and Australia at 50 hertz, because of two separate engineering compromises made in the 1890s, not because either number is better. Westinghouse settled on sixty cycles a second as a middle ground between slow steam engines, small transformers and flickering lamps, and German firms nudged a forty-cycle experiment up to fifty for much the same reasons a few years later.