Okay, he started 38 inches off the floor for a 84 inch bookshelf. But Billy still leaped from the (uneven) top of my office printer to the top of the seven foot bookshelf, partially cleared now that as part of the tasks around the house my brother has put up a proper speaker shelf.
It startled me too, I didn't know he was around until he crashed back down onto the printer. I wasn't sure where he had come from until I put a kitty treat up on the top of the bookshelf and watched him do the leap again.
Yup. Mighty leaper indeed.