Linn,
I remember many of the pictures and articles your dad photographed and wrote over the years... they ALL were well written and well illustrated. He was responsible for much of my current appreciation of the narrow gauge... and anyone who thought that a brace of K4's on the point of a train was just about as good as it got can't be all bad!
My mother passed from Alzheimer's (she was younger than your dad is when she died) a year and a half ago. I know all about the issues with memory from aging. I'm glad to hear he can still appreciate what's going on... even if he does forget later. You and he are very lucky.
Bill Daniels
Santa Rosa, California