History of the Welch Perpetual Calendar Clock
The Welch double-dial perpetual calendar clock is one of the most iconic American calendar clocks of the 19th century. Produced by Welch, Spring & Co., these clocks combined a standard 8-day time-and-strike movement with the patented B. B. Lewis perpetual calendar mechanism.
Identification & Authenticity
- Two dials: upper time dial, lower calendar dial
- Walnut or rosewood veneer cases
- Original Welch labels inside the case
- B. B. Lewis patent references on the calendar movement
Understanding the Movements
Upper Time Movement
- 8-day brass movement
- Countwheel or rack-and-snail strike
- Calendar trip lever triggers the lower movement daily
Lower Calendar Movement
- Day-of-week wheel
- Date ring (1–31)
- Month wheel
- Four-year leap-year cam
How the B. B. Lewis Calendar Mechanism Works
The mechanism automatically adjusts for:
- 28-day February
- 29-day leap-year February
- 30-day months
- 31-day months
How to Set Up the Perpetual Calendar
1. Use the Calendar Advance Lever Only
Never force wheels. Always use the built-in advance lever.
2. Advance to February 29
This synchronizes the four-year cam. Continue advancing day-by-day until the calendar displays February 29.
3. Advance to Today’s Date
Continue advancing until the calendar matches the current date, month, and day-of-week.
4. Synchronize the Time Movement
Advance the time hands forward until the calendar trips. Adjust so the change occurs near midnight.
Restoration Procedures
Time Movement Restoration
- Disassemble and photograph
- Let down mainsprings
- Clean plates, gears, pivots
- Polish pivots and rebush worn holes
Calendar Movement Restoration
- Document cam and wheel positions
- Clean lightly—avoid over-oiling
- Ensure month wheel and cam index correctly
Troubleshooting
Calendar Does Not Advance
- Weak trip lever
- Dirty pivots
- Worn bushings in the time train
Wrong Number of Days in February
- Four-year cam out of sync
- Calendar not set using February 29 method
Parts & Resources
For original and reproduction parts—including gears, cams, dials, hands, and hardware—visit:
VintageClockParts.com
Related Restoration Guides
Frequently Asked Questions
How do I set the perpetual calendar correctly?
Always advance the calendar using the advance lever until reaching February 29, then continue to the current date.
Why does my calendar skip months incorrectly?
This usually indicates the month wheel or four-year cam is out of sync.
Can I oil the calendar mechanism?
Use extremely light oil only on pivots. Never oil cams or date teeth.
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