I have 3 old Walthams I thought were model 57 the popular earliest style 18 size full plate. Found some confusion in records for 2 and one not marked Waltham that is a 57 with 1858 serial 11977 when Appleton Watch Co. was a year old. Very nice with full jeweling and gold balance marked for Rutland VT, Clark Brothers. Bartlett grade then. However, I have 2376 Dennison, Howard & Davis, a best grade made when Waltham was Boston Watch Co. preceding Appleton before 1857 so not a model 57 butlooks like the 11977. Has diamond cap jewel on steel balance. A 7j Ellery is a 57 model marked Boston only.