Walter Horn, also known as "Walt," celebrated his birthday at the Bowman House, an assisted living community in Three Rivers Wednesday with pizza, balloons, a little music and a big cake. The only thing bothering him Wednesday was the weather, which was giving him aches and pains in his leg, the beginnings of arthritis. The Bowman House calls it "Arthur." "He's in excellent shape," Arlene Parsons, activities director said.