Complication · Striking & chiming

Réveil (Alarm) à Toc

Partially verified

A miniature single-hammer alarm mechanism, striking directly against the case or a small stud rather than a tuned gong, giving a soft, discreet tapping signal rather than a loud buzzing or ringing alarm.

Definition

Historical origin

A traditional French and Swiss form of pocket watch alarm ('réveil à toc', literally 'knock alarm') produced from at least the nineteenth century as a quieter alternative to a fully audible alarm mechanism (see Alarm), sharing its basic setting and release logic with the standard alarm but differing in how the signal is produced.

How it works

As with a standard alarm complication, a separate alarm train is armed by winding its own barrel and set by aligning an alarm-disc pointer with the desired hour on the dial; at the set time, a pin or cam on the going train's motion work releases the alarm train, which then runs briefly to produce the signal.

Rather than driving a hammer against a coiled gong or a bell (as in a standard audible alarm), the à toc mechanism's hammer strikes directly against a solid stud, block, or the underside of the case, producing a soft series of taps that can be felt through the watch or heard only faintly at close range.

Because the striking action is otherwise identical to a standard alarm, an à toc mechanism still needs its own dedicated mainspring, wound and set independently of the going train, and the same care in synchronising the alarm-disc setting with the going train's motion work applies.

Pocket watch context

A recognised nineteenth-century pocket watch variant, generally produced in France and Switzerland, prized for offering an alarm function that would not disturb others nearby, in a manner directly analogous to the dumb repeater's relationship to the audible repeater.

Wristwatch context

Essentially absent from mainstream modern production; wristwatch alarms today are almost always designed to be clearly audible, since the discretion that motivated the à toc format is less often a design priority in contemporary alarm watches.

Identification

An alarm-setting mechanism (second crown or dedicated hand for setting the alarm hour) is present, but activating it produces only a faint tap rather than an audible ring or buzz
On inspection of the movement, the alarm hammer strikes a solid stud rather than a shaped gong or bell
Should not be confused with a standard alarm that has simply lost its bell or gong; an authentic à toc mechanism is built without one from the outset

Servicing notes

The alarm train's own mainspring, its release timing against the going train, and the alarm-disc setting mechanism all require the same specialist attention as a standard alarm complication; because there is no loud chime to confirm correct timing by ear, careful direct observation of the release point is needed during service.

General guidance only. Complicated mechanisms should be assessed and serviced by a qualified watchmaker or clockmaker specialist, not adjusted at home.

Diagram

Schematic: striking and sounding work. An outline schematic drawn to show the arrangement of the parts discussed here. It is not a dimensioned working drawing and does not depict a particular maker's calibre.

Sources & references

Britten, F. J., Old Clocks and Watches and Their Makers
Extent of nineteenth-century réveil à toc production not independently quantified from sources consulted.

Where sources disagree, the disagreement is stated rather than resolved silently.