The influence of metallic tractors on the human body [electronic resource] : in removing various painful inflammatory diseases, such as Rheumatism, Pleurisy, some Gouty Affections, &c. &c. lately discovered by Dr. Perkins, of North America; and demonstrated in a series of experiments and observations, By Professors Meigs, Woodward, Rogers, &c. &c. by which the importance of the discovery is fully ascertained, and a new field of enquiry opened in the modern science of Galvanism, or, Animal electricity. By Benjamin Douglas Perkins, A. M. Son to the Discoverer.