Large "sphere" shaped object sighted hovering with an up and down motion.

I wanted to report this event though it happened many years ago.  I never reported it to anyone before and thought it may be of interest to someone.
 I was 14 years old at the time of this sighting.  I lived in a rural area, on a farm.  On a Saturday morning I left my house to do some chores.  Across the road and approximately 100 yards from me, I immediately saw a large "sphere" shaped object about 50 feet in diamater, smooth and dark gray in color.  It hovered about 4' to 6' above the ground and moved in a slight up and down movement but made no sound.
 Being frightened by this unexpected sight, I quickly went back into my house.  After some time, I ventured back outside to see if the sphere was gone.  After looking around I saw that it had traveled across the road, and over our large farm pond and was now down behind a row of trees on the other side.  It's up and down movement seemed to be more pronounced but otherwise remained stable.  I once again retreated back into my house.  Not untill that evening did I venture back out to find that the object was gone.
We have assigned an arbitrary date in March 1962.  PD