Hello All, I just purchased a Hamilton model 22 chronometer. The markings on the bottom of the chronometer reads: MTD. Watch Bureau of Ships US Navy. N (in a circle) 7782-1941. The plate on the outside reads: N (in a circle) 7782-1941. The inside of the chronometer reads: Hamilton Watch Co. Model 22 - 21 Jewels Adj to Temp & 6 Pos, Made in USA With a serial number : 2F3817 I assume that this means Adjust to Temperature and the 6 Position scale above the seconds indicator. What does this do? It runs well and while the outer case needs work, the rest is very good. Where can I find replacement straps for the case? The glass covering the face of the chronometer is plastic, is this correct? What is an approximate age for this chronometer? Thanks all.