The coils are wound with copper wire (covered with silk), 10 mils.
It's so much more effective than rope, or wire, or chains.
Connexion is made into the office (or to the underground system, as is often the case) from the aerial wire by means of a copper conductor, insulated with gutta-percha, which passes through a " leading in " cup, whereby leakage is prevented between the wire and the pole.
Some of the containers had a thin wire running around but most were standing alone.
The description of that vehicle is plastered at every toll booth, state police barracks and wire service from here to California and back.