Object was silver-gray moved slowly made no sound at all.

UFO Report Gainsville GA.
Date: Approx. 1973  There were at least 7 to 10 witnesses. My brother and I were two of them.
We lived in a mobile home park on a ridge overlooking the Dawsonville Highway.
 It was  a bright sunny day.
The object was a perfectly round sphere. From where we stood it looked to be about thirty (30) feet in diameter. Compared to some buildings that it was moving over.
The sphere was silvery gray in color. Sort of dull like aluminum. It had no windows, portholes or anything hanging underneath it like a weather balloon does. Also no visible seams or bolts.
 This was not a weather balloon. I know what weather balloons look like. This sphere probably a couple hundred feet off the ground as far as I can estimate based on where we were looking down at the craft and at the highway with buildings on it.
 The craft was traveling slowly and seemed to be following the path of the highway. It was traveling horizontally, not going up like a balloon. It made no sound at all.
 There were no lights on it and we watched it for approximately 7 to 10 minutes until it disappeared behind another ridge with trees. We never saw it speed up or change direction or ascend. A balloon usually ascends as it travels. This sphere did not.
 Weather balloons have an instrument package hanging underneath it. This sphere had nothing hanging from it or protruding from it.
 This was before digital cameras and cell phones that took pictures so there were no pictures made of the object.
 The object must have been traveling west away from Gainsville on Hwy. 53.
Witness indicates that the date of the sighting is approximate.  PD