Cowboy Picture, 2003, a painting by Ed Ruscha © Ed Ruscha.

Charlie Siringo was that rare thing, a cowboy who wanted to tell you about it. Your archetypal ranch hand is gruff, laconic, but Siringo didn’t know when to shut up—he somehow glad-handed his way through one of the most stoic, lawless epochs of the nineteenth century. When he wasn’t making rope or lighting out for the territory, he was working on his memoirs, writing a pseudonymous gossip column, and honing his campfire bonhomie. “Charlie liked almost anyone he met who…