This is a closeup photo of one of the telegraph poles near one the main Post Office building in New York City at some time during the 1870s. Click "Next" for a full view of what this street scene looked like. Undoubtedly very early threaded glass insulators or threadless were used on the pole in this image. The earliest construction probably was strung along the four-pin crossarm on the top. Also, note some of the darker insulators on the lower (six-pin) crossarms beneath. Added note: a close-up examination of the original does not reveal whether any of these insulators were threaded or threadless. The latter is quite probable since the lines were used in a more tranquil enviornment (in the city) ; not opposed to exposure to open hazards along railroad routes.