Alarm

Definition

A mechanism that sounds an audible signal at a pre-set time, using a separate striking train and hammer independent of the main timekeeping train.

Historical origin

Mechanical alarm clocks date back centuries, with alarm pocket watches known from at least the eighteenth century; the mass-market mechanical alarm wristwatch is strongly associated with twentieth-century Swiss production, notably Jaeger-LeCoultre's Memovox line introduced in 1950.

How it works

Pocket watch context

Alarm pocket watches, sometimes called 'reveil' watches, used a small hammer and bell or gong housed within or behind the case, wound and set via a separate mechanism from the timekeeping train.

Wristwatch context

A specialist complication, most associated with mid-twentieth-century models like the Jaeger-LeCoultre Memovox, valued today partly for the mechanical ingenuity of producing an audible alarm in a wristwatch case.

Clock context

Alarm clocks are among the oldest and most common applications of the complication, using a bell struck by a separately wound train released at the set hour.

Identification

• A separate winding crown or a rotating inner bezel/disc for setting the alarm time, distinct from timekeeping winding and setting
• Visible or audible resonance chamber, gong, or bell depending on the object type
• A slide marked 'On/Off' or 'Alarm/Silence'

Servicing notes

The alarm train's separate mainspring and release mechanism should be assessed alongside, but distinctly from, the timekeeping train; complicated alarm watches and clocks should be serviced only by a specialist familiar with striking mechanisms.

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