I saw something strange

On a Friday night about the middle of March, 1966, just after 8:00a.m., we were going down a hill, newly excavated, as part of the I-95 project.  Half way down the hill at the bottom of a newly excavated roadway, a round silver, metallic object came over the brow of the embankment very slowly and hovered there slightly wobbling.  It suddenly disappeared.  A coil of black smoke was seen in the light of the traffic light at the bottom of the hill.  There is an electric power sub station on the top of the embankment at the bottom of the hill.
There was a care ahead of us.  It stopped and  so did we.  Then we saw a round ,silver metallic object.  It looked like one saucer upside down over a right side up saucer.  On the top, at the bottom of the rise of the dome were opaque, lit, windows.  At the center of the bottom was a black disc that rotated.  Iridescent sparks were seen at the perimeter of the disc.  There was no noise noted from the object.