I found this yesterday at an 1880’s property just NW of Chicago. It “looks” like a ceramic or clay, glazed marble inside a non-ferrous, 1"-diameter “octagonal nut”. There are no threads for attaching on the smaller, reverse side. Any ideas?
The Englishman Richard Hollins Murray invented these in 1927 and filed his American patent the same year. They were originally intended for advertising use but soon adopted for other purposes such as road signs. Another Englishman, Percy Shaw, adapted the technology for use in road-marking (set into the tarmac in pairs in an ingenious housing that kept them clean). We have them in the UK on every major road for lane-marking, but that didn’t catch on as widely in America as it did for highway and railroad signage.
When Shaw patented his adaptation he also registered “Catseye” as a protected trademark and, although the general public often called all such devices by that name, the unprotected industry name was “cataphote reflector”.