Western Union utilized six-pin crossarms with double-petticoat insulators as standard construction commencing in the 1890s. About 1910 ten-pin crossarms became their standard. Postal and the B&O telegraph companies continued to employ six-pin crossarms where fewer wires were attached after the teens at least here in southern New England (albeit neither had a lot of routes here via my early day scouting adventures) so this line could have been operated by other than Western Union...