I used to own a little Hardy model Hamilton that was powered by a 921, it was a pretty good watch, handsome too.
Looks like these were very expensive watches for their day. http://www.hamiltonchronicles.com/2013/12/1949-hardy-pocket-watch-921-movement.html
I sold mine for $75 when I decided that I was going to focus on railroad watches. Sometimes I regret it because it was a nice little watch, I still own a similar Waltham that has a bad balance.
I just picked up this beauty at an antique store for $25 while visiting family in rural Montana !! Hamilton grade "Special 974", size-16, with 17 jewels and a 10K yellow gold filled case. Referred to as the “Traffic Special”, it was produced from 1928 through 1940 for electric commuter train services. This example is apparently from the later production years, as it was cased by the Star Watch Company (stamped caseback), which were a small subset of the later production models. Currently running; but dry as a bone and desperately in need of a service, so it's off to the spa later this week !
My friend owns one of the 35 originals from 1928... the one presented to catcher Bill Dickey. I get to borrow the watch every once in a while.
Been eying the khaki for a while, pulled the trigger on brown dial...have too many white and black dials, and the brown is subtle, “tropical”-ish. Will probably put on a different nato—not a fan of the leather accent on the standard band. Nice, simple, no date, thin and legible. Look fwd to wearing.