Complication · Display
Barometric Indication
Partially verifiedA subsidiary dial or hand showing atmospheric pressure, typically driven by an aneroid capsule linked to a pointer, incorporated into a clock (rarely a watch) alongside ordinary timekeeping.
Definition
A subsidiary dial or hand showing atmospheric pressure, typically driven by an aneroid capsule linked to a pointer, incorporated into a clock (rarely a watch) alongside ordinary timekeeping.
Historical origin
Barometers were combined with clocks in decorative 'clock and barometer' sets from at least the eighteenth century, particularly in English and French domestic clockmaking, well before the aneroid (spring, non-liquid) barometer was developed in the mid-nineteenth century by Lucien Vidie; the aneroid mechanism's compactness subsequently made combined clock-barometer instruments, and eventually a small number of barometer-equipped watches, more practical.
How it works
An aneroid barometric mechanism uses a sealed, partially evacuated flexible metal capsule that expands and contracts with changes in ambient atmospheric pressure; a lever-and-gear train amplifies this small movement and translates it into rotation of a pointer over a graduated pressure scale.
Because a barometric mechanism responds to ambient air pressure rather than to any mechanical timekeeping input, it is entirely independent of the going train and is typically mounted as a separate module sharing only the case (and sometimes the dial) with the clock or watch movement.
In combined clock-and-barometer instruments the two mechanisms do not interact mechanically at all; in the rare cased watch examples, the barometric capsule and its linkage must be fitted into a very constrained case volume alongside the going train, which limits both the achievable pressure-scale resolution and the mechanism's robustness to shock.
Pocket watch context
A rare nineteenth- and early twentieth-century novelty in combined 'compass, barometer and watch' cased instruments and specialist travelling/outdoor watches, generally produced in smaller volumes than complications relating purely to timekeeping.
Wristwatch context
Occasionally offered in modern specialist and outdoor-oriented wristwatches as an aneroid-capsule barometric complication, though far more commonly implemented today via an electronic pressure sensor in quartz or smart instruments rather than a genuine mechanical aneroid mechanism.
Clock context
Well established in the English and French tradition of combined clock-and-barometer wall or mantel sets, where a conventional (often mercury, later aneroid) barometer is mounted beside or below a clock dial in a shared case, primarily as a household instrument rather than a mechanically integrated complication.
Identification
- A separate graduated dial marked with pressure-related terms (e.g. 'Stormy', 'Rain', 'Change', 'Fair', 'Very Dry') or a numerical pressure scale, distinct from the timekeeping dial
- Mechanically independent of the going train; setting or winding the watch or clock does not affect the barometric reading
- On a genuine mechanical example, the barometric pointer will visibly respond over hours or days to real changes in ambient air pressure, not to any input from the wearer
Servicing notes
Aneroid capsules and their linkages are outside the scope of general watch and clock training; a barometer specialist or an instrument restorer experienced with aneroid mechanisms should service this module, and it should be regarded and serviced separately from the timekeeping movement it shares a case with.
General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.
Diagram
Sources & references
- Britten, F. J., Old Clocks and Watches and Their Makers
- General literature on the aneroid barometer (Vidie, 1840s) and combined English clock-and-barometer sets; comprehensive documentation specific to barometric pocket watches is limited in sources consulted.
Where sources disagree, the disagreement is stated rather than resolved silently.