The latter (seen between the upper two crossarms on the right side of the pole) were known as junctions whereby the overhead electric circuits connected for routing down the pole for underground electric distribution (note the pipe extending downwards on the pole). "Potheads" typically had three bushing-type insulators atop them in a finger-like arrangement (as seen here), mounted on a cast iron casing which was filled with oil so that the internal connections would run at a cooler temperature. They were used for primary voltage circuits, typically 2,200 volts and up. This is a pretty old and neat looking cross-over pole, by the way. Its "pencil top" design certainly adds lots of character to this "display" :-)