Perkins's Patent Metallic Tractors

Perkins's Patent Metallic Tractors (or Metallic Instruments, Metallic Points) are sets of three-inch, single-pointed metal rods, designed and patented by Elisha Perkins in 1796, which were sold for use as an electro-therapeutic cure of various "local inflammations, pains in the head, face, teeth, breast, side, stomach, and back." Through contact with the afflicted area, the tractors would, according to the inventor and his promoters, act as attractors, "drawing off the noxious electrical fluid that lay at the root of the suffering" to bring about "blessed relief."