These awesome poles probably were built around 1900. Note the intrinsic detail to their design...especially the crossarms. The latter were detachable from their poles. These arms had either wood or steel pins inserted in them. Others had their cast iron pins integral as part of the entire "crossarm" unit.

More "holy grail" stuff for Lou Hall to keep on looking for, lol ;-)

Added note: The lowermost crossarm facing you and the one on the upper portion of this pole serving as a crossover line both were wooden with metal clamps affixing them to this pole.