For those of us who don’t play a brass instrument, watching brass players play always seems a bit like watching a magic show. We hear the French hornists, trumpeters, trombonists, and tuba players playing plenty of different notes, but the number of times they move their fingers — or in the case of trombonists their slides — doesn’t nearly add up to the number of notes. Not to mention the fact that where they put their fingers or slides doesn’t seem to bear any relation to which notes they’re playing, a mystery compounded by the fact that horns, trumpets, and tubas only have three keys to press, three valves. How do they do it?