Jesse Ramsden (1735-1800) – the master scientific instrument make of the 18th century produced all manner of instruments of astronomy, navigation and surveying.  He is perhaps best known for developing the precision dividing engine.  His electrostatic generator combined a rotating glass plate , leather friction pads and tubular brass capacitors isolated by glass supports to deliver a therapeutic current in as many ways as the imagination could conceive.  Despite the absence of any proven merit to such therapy, variants of Ramsden’s deviceflourished into the 20th century.  Tesseract – Catalogue Eighty-Six. A fine, unsigned example in good working order and retaining 90% of its original clear lacquer finish