- This chart summarizes when certain features were introduced. This is mainly for illustration; individual tables will generally be more useful. Plus, Homes & Broadways are not listed.
- Please be aware that the data tables contain raw data; some mistakes can be expected from data entry and submitters. Use discretion. Look for patterns, not single examples. Interestingly, feature changes usually follow serial number and not date of production (although there are exceptions); the reason is probably that material was reserved based on serial number and features were not retrofitted when the movement was actually made.
- A major point I want to make about this information is that I would argue that the value of a particular movement is higher if its serial number is close to when a feature was changed.
- One example is when the city marking (Boston vs Waltham) changed as previously mentioned. Another, the first SO hairspring for a particular grade.