This happened around 1953 in Upper Dublin Township, Pennsylvania at the Fitzwater cemetery, Twining Road. This cemetery has a large stone wall around it about 4 to 5 feet high.
I was riding my horse past the cemetery as I was heading for home like I normally do. I lived up the hill from the cemetery about 500 yards. In the woods my horse was always skittish going past that cemetery around dusk.
This evening she was especially skittish and had her ears up, her body and head turned, and was sidestepping. I looked over at the cemetery and I saw a young lady sitting on the favorite big tombstone every one likes to sit on.
This young lady waved to me so I waved back. I smiled and yelled over to her, "Hi!" She smiled back. As we watched, her raised hand started to evaporate at the top and continued on down her arm and then the rest of her just slowly vanished.
Well this raised the hair on the back of my neck and goose bumps ran up my spine. We crossed the road quickly and up the dirt bank I turned my horse towards home and we ran the rest of the way.
Since then we would give the cemetery a wide path and my horse was still always skittish going past but we never saw the young girl after that.