OK, I'm intrigued!
A steel rule, inverted image? But I don't think it is a scale in inches, because there are five divisions - so tenths, but tenths were very rarely used, eighths or sixteenths.
Then, there are the two sides, with a clear offset, but presumably both have a similar origin point. So are they different scales? Perhaps a vernier? But attempts to carefully measure suggest the scales are the same.
So, I am stumped!
A steel rule, inverted image? But I don't think it is a scale in inches, because there are five divisions - so tenths, but tenths were very rarely used, eighths or sixteenths.
Then, there are the two sides, with a clear offset, but presumably both have a similar origin point. So are they different scales? Perhaps a vernier? But attempts to carefully measure suggest the scales are the same.
So, I am stumped!