Oxford University bell has rung 10 billion times, powered by a 175 year old battery

[link to www.physics.ox.ac.uk]

The Clarendon Dry Pile was purchased by Robert Walker (Professor of physics 1839 - 1865) and bears the label in his handwriting "Set up in 1840", though a later note indicates that it may have been constructed some 15 years earlier. It consists of two voltaic "dry-piles", covered with an insulating layer of sulphur, connected in series and, at their lower ends, to two bells. Between the bells is suspended a metal sphere about 4mm in diameter which is attracted alternately by the bells and transfers charge from one to the other. The frequency of its oscillation is about 2Hz; so far the bells have been rung of the order of 10 billion times.