It's an overview of many different recreational topics. Of particular interest, it covers: Bowling and Tennis (both only briefly, I'd afraid); Riding and Racing; the Science of Defense (that is, fencing); and Ringing of the Bells (
While I'm at it, my nominee for the latest Amusingly Useless Book: Ars grammaticae Iaponicae linguae, a 1638 grammar of Japanese -- written in Latin...