Typical telegraph line construction seen here in the East from the 1880s until around 1920 when Western Union (and competing companies) rebuilt their lines using 10-pin crossarms as standard. These upgrades often involved the installation of solid, hard-drawn copper wire replacing old iron wire.

During such upgrades insulators and other hardware from the predecessor construction were often re-used with the new build. Thus early Brookfields and Hemingrays of the pre-1900 years that were standard or acceptable (such as CD 145s) made their way onto the newer lines, intermingled with the then-new insulators at the time of the rebuild. Thus making it more interesting for us collectors who collect insulators and old hardware ;-)