Rich- You came to the right spot but I need more information to give you a $ guess. What is the serial number on movement? Gold or silver case? Masonic markings on dial or fob? Also is it 18 or 16 size? Measure the movement across the inside of the back of the case.
18 size ~1&11/16, 16 size ~ 1&5/8 inches. Also what kind of condition, avg, ex fine or mint?
I have the Shugart,Engle,Gilbert book, Complete price guide to Watches. Has all the old pocket watches listed and Hamiltons run anywhere from $125 to $7000 for rare ones. A 1999 edition but will give you some idea. Also will give you the age of the watch
Don, watchmaker.