Oxford Electric Bell

The Oxford Electric Bell or Clarendon Dry Pile is an experimental electric bell that was set up in 1840 and which has run almost continuously ever since, apart from occasional short interruptions caused by high humidity. It was "one of the first pieces" purchased for a collection of apparatus by clergyman and physicist Robert Walker. It is located in a corridor adjacent to the foyer of the Clarendon Laboratory at theUniversity of Oxford, England, and is still ringing, though inaudibly, because it is behind two layers of glass .... http://en.wikipedia.org