Read the hour without light, and without the noise of minute or quarter repeaters: this is why Breguet invented the montre a tact (discreet watch)
Back in the days before artificial light, a crucial issue was how to check the time in the dark – without waking up the whole house turning on candles or fireplaces. In order to help the noble gentlemen of that age, some ingenious devices were invented, among them the still nowadays fascinating repeaters. But the repeaters were very evident in the silence, especially in the theatres.
And what if you want to check the time in the dark – and be discreet about it? This is why Breguet proposed to his XIX Century’s customers the montre-a-tact (“discreet watch”). This watch allowed to check the time without pulling the watch out of their pocket or sounding a chime. It had a large hand –in the shape of an arrow- affixed to the outside of the case. A mechanism integrated into the cover allowed the hand to rotate counter-clockwise until it matched up with the hour hand on the dial, where it would stop. A series of ridges or bumps along the edge of the case indicated the hours to help understanding the exact time. So by rotating the external hand into position and feeling for the hour markers, the wearer could get a rough estimate of the time.
Where a repeater or sonnerie was extremely expensive to produce, the montre-a-tact was easy to build, helping this invention to become quite popular among the high society of the 19th century.