No electricity required. This lovely old door bell is operated by clockwork mechanism. Legend to the front of the case is by her majesty's royal letters patent. Unfortunately Espacenet returns no results for this and similar searches so we can't be sure of a date. The bell is made to ring by pulling down on the chain which winds the spring. Letting go of the chain rings the bell. Fittings for the supplied chain are widely available. Secure to the wall with two screws through the holes at the top and bottom. Possible applications only limited by your imagination. A most unusual bell.