Davis and Kidder's magneto-electrotherapy machine, hand-cranked, made by W H Burnap of Lowell, Mass., U.S.A., 1854-1898

Widely available, these portable devices were used to generate therapeutic electricity in the home or by travelling practitioners. Turning the handles produced an electric current. Damp sponges in the brass cylinders prevented a prickling sensation on the skin. Users and makers claimed the devices could relieve pain and cure almost everything, including cancer and heart disease.

Ari Davis (1811-1855) was a craftsman who received a patent in 1854 for this type of magneto-electric machine. Davis sold the rights to the patent to Walter Kidder, a physician in Lowell, Massachusetts, allegedly for $4000. Their device was often advertised as Davis and Kidder’s patent magneto-electro machine. This example has the signature of W H Burlap across the instructions who made the device and also purchased the patent from Kidder in 1856.