An attractive turn of the century quackery device in the form of a pendant. The knowledge that electrical currents were created when certain metal were juxtaposed was the basis on which many such devices were said to have widespread therapeutic effects as galvanic generators (galvanism).
One of the more common of these was the Boyd’s battery. This example is most unusual in having the metals framed in a gagate (jet) pendant. The reverse side shows and exquisitely rendered cherub with electric bolts emanating from both hands with the periphery embroidered in flowers. Marked London Galvanic Generator, Pall Mall Electrical Association (mentioned by the London Evening Post in their 18th June 1892 edition)