The plate on the back indicates it was patented in 1914. It is unique in that the user sets the altitude of his location to obtain an accurate reading. The body of the instrument appears to be copper but there are indications that it was brass plated. It is in good shape and I have noticed changes in the readings over the past several days. There is minor cracking of the paint on the dial. It is 5 1/8″ in diameter and 2 1/2″ deep.
