Bryant Park, behind the main Public Library branch in New York City, is transformed into an ice rink each winter. Skating is free of charge if you bring your own skates, making it one of the best deals in town. The rinks at Rockefeller Center and Central Park are for the tourists, but this is New York’s backyard rink. I skate there two or three times a week, but this week has been exceptionally memorable. An extended spell of cold weather cured the ice to the point where it was as hard and fast as the pond and marsh ice that I used to skate on in my youth. Arena ice never gets that way, being frozen from below and constantly melting at the surface. And unlike pond ice, the park rink this week was smooth and ripple-free, and there were no cat-tails to step around. In the early morning when few skaters are out there, it’s one of the most pleasant things you can do in the city.