Electrotherapeutics / Trans. by A. de Watteville.

  • Erb, Wilhelm Heinrich.
Date:
1887
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Licence: Public Domain Mark

Credit: Electrotherapeutics / Trans. by A. de Watteville. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

    55/762 (page 27)
    IND UCTION APFARA T US. cuiTents are generated in both secondary and primary coils, and these may be sent through the human body by means of appro- priate arrangements. Graduation of such currents is effected in various ways, such as by pushing the coils towards or from one another, by moving the core of iron wires in or out, &c. The point which you must always keep clearly before your eyes is that you always have to do in the induction currents with a large number of successive and rapid fluxes of instan- taneous dm-ation—very different from the uniform and equal flow of the ' constant' or galvanic current. Addressing myself now to the usual inductoriums and batteries, I shall give you a short account of their principles rather than of the details of their construction. It seems to me useless to enter upon a description of all or even a few of the innumerable and more or less practical forms now in existence. I shall rather insist upon the conditions which such apparatus must fulfil, and then pass to a fuller account of the in- dispensable accessory apparatus required in medical applications. The first condition required from an induction apparatus is that it shall have large enough coils to yield sufficiently- strong currents, and that the length and thickness of the primary and secondary wires have an approximate relation. Secondary coils of very fine wire always appear to me to yield more painful currents. Provision must be made for the ready use of either the primary or secondary current and for the adequate graduation of both. Finally, the automatic inter- rupter must act regularly and at the required rate; the galvanic elements must have sufficient electromotive force and durability to furnish the necessary current; and the primary- coil must have a sufficient number of turns of wire of the- required thickness. These.conditions are more or less fulfilled by the numerous apparatus now generally in use. In all scientific researches, and in medical application at the physician's house, the best form is the well-known ' sledge' of Du Bois-Keymond, such as is commonly met with in physiological laboratories. This form of instrument is made with various but unimportant modifications, and is supplied with a scale which it is best to graduate so as