Elizabeth Cavicchi Nineteenth Century Medical Induction Coils (Dr. Elizabeth Cavicchi conducted research at The Bakken in December, 2003) Electricity affects our bodies in ways that can hurt or heal us. When electricity was first produced as a continuous current from chemical batteries in the nineteenth century, experimenters often let its shock go through their bodies and some physicians treated patients with it. But human skin is so resistive to low voltage electricity, as was evolved by those early batteries, that the medical uses remained limited. With the emergence of the medical induction coil around 1840, this situation changed. It ran on a single small chemical cell, yet it output intermittent electricity of high voltage that readily stimulated the human body with shocks, muscle contractions, and other sensations. In a typical double coil device, battery current passed through a thick wire that coiled tightly around an iron rod, magnetizing it. When this rod was magnetized, it opened a switch, stopping the current and giving rise to a high voltage pulse in the long outer coil; this pulse could be directed into a patient’s body. The instrument was compact, portable, inexpensive, and even operable by the patient. It was commonly available: commercially from instrument-makers; informally through amateurs who made their own. While the medical induction coil is discussed in some histories of medical electricity and of the induction coil, it has not received scholarly attention on its own. My research stay at the Bakken Library and Museum was a beginning effort to understand the instrument and its uses, such as: the variations among the many medical coils; ways the coil was activated and applied to patients; and how medical practitioners reported on, and understood, the electrical treatments they administered. My research combined studying a range of historical texts, and examining actual medical coils in the Bakken’s instrument collection. I looked at publications relating to the medical coil’s history and use. Illustrations, descriptions, and prices of the instruments were provided in trade catalogues, such as: C T Amsler, Illustrated catalogue of philosophical instruments, Philadelphia, 1857; GalvanoFaradic Manufacturing Co. Portable…machines NY 1871; Jerome Kidder, Dr. Kidder’s highest premium…electro-medical apparatus, NY 1871; Salt and son, Practical descriptions of every form of medicoelectro apparatus, London 1875. Methods of applying the coils’ electricity to patients’ bodies and strategies for treatment of various disorders were discussed in manuals such as Robert Froriep, On the therapeutic application of electromagnetism in the treatment of rheumatic and paralytic affections…London 1850; Harry Lobb, On the cure of paralysis…galvanism, London 1859; Albert Steele, Theory and practice of electrical therapeutics…NY 1871. Most fascinating were two of the major texts of medical electricity, its applications and treatments. These were Beard and Rockwell’s Medical and Surgical Electricity (1871 and many later editions) and Duchenne’s Treatise on localized electricity (translation) Philadelphia, 1871. Passages in these volumes detailed the experimental process by which these prominent physicians actually invented and improved new electrical apparatus and created innovative protocols for their use. From the Bakken’s extensive collection of medical induction coils, curator Ellen Kuhfeld selected coils having different designs and mechanisms for me to study. I made sketches and diagrams of each coil as I tried to work out its wiring and other characteristics. I used a micrometer to measure linear dimensions of the coils and their constituent wires. With a multimeter, I looked for continuity in the wiring and across the instruments’ terminal screws. In some cases, it was possible to record values of the electrical resistance across portions of an instrument’s wiring. With this detailed approach, I looked at 20 instruments in the collection. These included Duchenne’s Volta-faradic coil and his magneto-electric apparatus; Halse’s medical coil with a clock-face dial; Hearder’s prize Condensed Galvanic Machine; a Sledge coil where a crank moves the outer coil away from the inner, primary coil. I found there was a productive exchange going on between reading the historical texts and looking at the instruments. This was most evident in the case of Duchenne’s work. In his Treatise, I read thorough descriptions of the separate parts of the faradic coil and magneto-electric machine. Seeing these instruments directly made the identity and relationships among these parts clearer to me. On rereading Duchenne’s text again, I began to follow his instructions for putting the instrument into action. Then I returned to the collection, and looked for a particular attachment that was mentioned in the text. I found that it was not included in the Bakken’s instrument, and may have been an earlier design. A similar deepening in what I noticed about the instruments occurred as I gained more experience through working with the variety of medical coils, and through talking daily about my questions and observations with the curator of instruments. Dr. Elizabeth Cavicchi To contact Dr. Elizabeth Cavicchi, contact Elizabeth Ihrig, Bakken Librarian, at 612-926-3878 ext. 217 or via e-mail using her last name @thebakken.org.
Dr. Elizabeth Cavicchi sketch of a Vertical Coil with Electrolyte Regulator, Number 74.13.66 in the Bakken instrument collection
Dr. Elizabeth Cavicchi sketch of Dancer’s Vertical Coil, Number 81.107 in the Bakken instrument collection
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