Old Curtis air compressor gauge

I took a chance and purchased a box lot full of old gauges for $1 at an estate auction a few weeks ago. Most of the gauges were older with fancy numbering and needles. It only takes one good gauge to make it a bargain and I think this was the one. The others in the lot were no more than scrap after researching them all. I built a test connection with a new air gauge to compare psi's and both were in sync so still accurate readings too.
small markings at perimeter 2 1/2 AD - 1096