I've got an old screw pitch gauge that I inherited. There's no mfr's name marked on it, just "Number 137".
the individual leaves are marked with two numbers each, but these numbers are not reciprocals. The first number is always a small integer which I presume is threads-per-inch.
the second number is always a decimal.
All the leaves are of equal thickness, so they are not thickness calibrations as in a feeler gauge.
Any idea what the second set of numbers are?