I've looked everywhere for an answer. Hopefully this is the right place. In most older towns, I've noticed these old wall plates.
They appear to convey some kind of information but it escapes me exactly what. They look about 100 years old in most cases. They're also marked with what looks like measurements, but I don't know what they correlate to. Does anyone know what they are?
Just a water mains valve marker plate. Top number is the valve diameter and bottom number is the horizontal distance from the plate. Not particularly old.
Please get better pictures, and consider crossposting on /r/whatisthisthing
