Obviously it is an Inspector's badge from the water department, but that is all I know. A search brings up NOTHING specific. It is made of brass, silver plated with what appears to be blue porcelain inlays, about the size of a silver dollar and has a "safety pin" type clasp on the back. I'm trying to find out when these were in use and how rare are they. Actually, any info would be awesome! Thanks in advance.