The Bartlett became Robbin's mainstay Model 57, the middle ground grade, and was produced throughout the entire life cycle of the Model 57. As can be seen on this 11J example made in 1869, it is fitted with an expansion balance like the two higher AT&Co and WWCo grades. Although there are exceptions (perhaps not original), the two lower Ellery and HWCo grades were not given expansion balances. With these five varying grades of M57s, by 1869, Robbins was making a watch to fit every taste and pocket book.
