Well, Grande sonnerie (French, meaning 'grand strike') is a complication in a mechanical watch or clock which combines a quarter striking mechanism with a repeater. On the quarter-hour, it strikes the number of hours audibly on a gong, and then the number of quarter-hours since the hour on a second gong. In addition it can strike the hours on demand, at the push of a button. The term is sometimes used erroneously for a mere quarter striking mechanism.
It is more complex than the petite sonnerie, which merely strikes the hours on the hour and the quarter hours on the quarter, with no repeater function.
What's the big deal? And how does it work?
- In the noted horology book "Britten's Old Clocks and Watches", G.H. Baillie defines a Grand Sonnerie movement as follows:
- "A form of quarter-striking in which the hour last struck is also repeated at each hour."
- It works like this, striking the quarter-hour on one gong and the hour on a second, slightly lower-toned gong:
- At 3:15 the clock strikes once on the higher chime to indicate the quarter hour, followed by three strikes on the lower chime to indicate the hour.
- At 3:30 the clock stikes two times on the higher chime (half-hour), followed by three chimes on the lower gong (hour) ...etc.
- This way, if you are within hearing distance of the clock, day or night, you can tell exactly what time it is at each quarter hour.
- A "petite sonnerie" movement strikes once on each quarter and then the hour on the hour.