... mais le "truc" ne sera révélé qu'après son arrêt .... peut être ... =)
(« The exact composition of the dry piles is unknown »)
As a result, the batteries drain very slowly, which is why the piles have been able to last since the apparatus was set up in 1840. Its oscillation frequency is 2 hertz, or every half second.
Bref, elle sonne toutes les ½ secondes, enfin sous sa cloche de protection/isolation sonore. Énervant nan ?
Oxford Electric Bell
Source: en.wikipedia.org