The combination of these two spins gave Mercury a very slow roll through its solar day, during which the brightside hemisphere became much too hot, while the nightside hemisphere became extremely cold. The lone city currently on the planet was therefore a kind of enormous train, running around the planet on tracks set on the northern forty-fifth latitude. These tracks were made of a metalloceramic alloy that was the first of the Mercurial physicists’ many alchemical tricks, a matrix that withstood the eight-hundred-K heat of midbrightside.
