The efficacy of Perkins's patent metallic tractors in topical diseases, on the human body and animals; exemplified by 250 cases, From the first Literary Characters in Europe and America. To which is prefixed, a preliminary discourse, in which, the fallacious attempts of Dr. Haygarth, to detract from the merits of the tractors, are detected, and fully confuted. By Benjamin Douglas Perkins, A. M. Of Leicester-Square; (son Of DR. Perkins The Discoverer.)