On top probably is a fire alarm call box circuit. The "tall" insulator looks like a CD 156.1. Immediately beneath are electric service distribution lines with CD 162s. Next, on the middle 6-pin crossarm are telephone circuits (note the CD 112 insulator with two wires tied to it). The heavier cables on it look like they were for trolley service. The latter crossarm likely was for the trolley company's private phone line (used for dispatching purposes). The rest of their cables are on the lowermost arm. Note the CD 259 on the left side of it . I have no idea what the lighter signal-style insulators supporting a couple of the trolley cables were. My hunch is that they were made of composite material.