In less than fifteen years after the trial of the pretensions of Mesmer and his coadjutors, in regard to magnetism, there was originated in America, by a Mr. Perkins, a cause of delusion of precisely the same nature. It prevailed in all the United States, in Great Britain, Scotland, and Ireland, and to considerable extent on the continent of Europe. Mr. Perkins prepared two small pieces of different kinds of metal drew them to a point, and polished them. These _Metallic Tractors_, as they were denominated, were said to have, in their joint operation, great power over the electric fluid; and by moving these points gently over the surface of an inflamed part, the heat was extracted, the swelling subsided, and, in a short time, the patient was relieved. After a while, thousands and tens of thousands were ready to certify to the happy influence of these _Tractors_. Mr. Perkins went to England and obtained the royal letters patent, for the purpose of securing to him the advantages of his discovery; and it has been asserted by the best authority, that he returned from England possessed of ten thousand pounds sterling, which he received for the use of his Tractors. But Dr. Haggarth, an eminent physician and philosopher, recollecting the development of animal magnetism at Paris, wrote to Dr. Falconer, surgeon of the General Hospital at Bath, (England,) and stated his suspicion concerning the Tractors; that their efficacy depended wholly on the imagination of the patient; and recommended the experiment of _wooden_ Tractors in the place of the _metallic_.