In that year, the Hamilton Watch Company came into existence as a result of yet another reorganization. Based on the super-reliable 992B with Elinvar hairspring and mono-metallic balance, the Mod 23 adds a chronograph mechanism, making it one of the most complicated watches produced by Hamilton.
In general, we think of serial number lists (not just for Hamilton, but for other watch manufacturers as well) to only be accurate within a year or two at best, and recognize that there are numerous exceptions wherein which the dates may be off as much as 3 years or more. "Timely Voices - A Hamilton 992 Inconsistency," Kent Singer, NAWCC Bulletin No.
Hamilton was granted the land by William Penn's heirs and is credited with founding the city of Lancaster with his son James. The Elinvar hairspring was patented in 1931 and used in all movements thereafter.
Hamilton Watch was founded by merging Keystone with the Aurora (Illinois) Watch Company. The name Elinvar was derived from the term "Elasticity Invariable" and was the first alloy to resist the changes in elasticity that occur with changes in temperature.
Some companies (as with the Gruen Watch Company), even lost rocords to fire or other natural disaster. I am sure they had no idea that their timepieces would someday be collected.
There are several ways to get an idea of when your watch was made.