I recently acquired a post card collection and came across this one of the Mount Washington summit. I noticed the posts with what looks like square blocks mounted to them and came to the conclusion that this must be the famous telegraph line that went to the summit. I grew up not far from Mount Washington (Berlin NH) and I remember as a kid seeing a barrel full of these blocks complete with the insulators for sale at a small antique shop in Gorham NH......this was back in around 1973......I remember they were being sold for $5 without the wooden block and $10 complete.