since you do not want to open the back ( which is easy to do) and show the case markings and movement I would say that it is either:
1) a base metal 7 jewel Elgin in nonworking condition, with missing parts circa 1920's worth $5 at yard sale. OR
2) a solid 18K gold 21 jewel railroad quality watch in mint condition and working wort about $2000, OR
3) or somewhere in between
too bad you dont want to open it and find out