The Island of the Day Before by Umberto Eco

This book reminds me a lot of a certain kind of witty historical fiction--the kind of thing you might read in Neal Stephenson's Baroque Cycle, for instance. It's the story of Roberto, a young nobleman who gets caught up in Parisian politics and sent to spy on developing science (here, the goal is to calculate longitude), but ends up shipwrecked on a deserted (or maybe not quite deserted) ship. The book is highly meta-fictional: the narrator is coy about how he came into possession of Roberto's papers, although fairly upfront about how much he makes up or supposes along the way. The book is a lot of fun if you're into seventeenth century scientific theories, early novels (this story can't help but remind me of Robinson Crusoe), or meta-fiction generally.