A Medical Coil by Griggs

c. 1875, electro-therapy device, the coil in a turned mahogany case with adjustable iron rod core, with engraved silver-plated plaque 'Grigg's Conical Electro Magnetic Machine Patented Jan 8th 1873 London, Sole Manufacturer J R Chislett 35 Union St Plymouth', mounted on mahogany base board with magnet, contact breaker and lacquered brass terminals, with mahogany handled sponge, all in wooden case, coil base 27cm across, in original case with instructions to underside of lid

Note missing soft iron control rod.