We have now brought the electricity to the terminals of our battery, and we must next consider the best means of conveying it to the sponges, conductors, or, as they are generally termed, rheophores or current carriers, by which it is finally applied to our patient. [SN: Conducting Cords.] Our first necessary accessory is a conducting cord or wire, and it is of the first importance that this should really be what it is called--“_a conductor_”--for any fault or break of connection in it will, of course, nullify the best and most perfect battery. It must also be sufficiently pliable, and be insulated by being coated with some non-conducting material that the electricity may not escape from it to any conducting substance with which it may accidentally come into contact. The conducting cords sold by instrument-makers are sometimes not insulated at all, and then they are quite useless, but they are more commonly composed of several strands of metallic wire of about the diameter of sewing thread, the whole enclosed in some silken or woollen material, and nothing can be better than these latter when quite new. Their disadvantages are that they become frayed after a little use, and are liable to be constantly out of order, causing interruptions in the current, while they will only fit one kind of machine. I have had endless trouble with them; and for some years I have used nothing but thin copper wire, coated with gutta percha in the same way as that known as “telegraph wire.” This is perfectly insulated, sufficiently pliable for all practical purposes; it is cheap, and can be made to fit any sort of connection. Its one disadvantage is, that it is liable to break at the point where it is received into the terminals of the battery, or the screw socket of the rheophore. Should this happen, all that is necessary is to scrape off the gutta percha coating with a pocket knife for an inch from the broken end, by which we get practically a new conducting cord. We have now considered fully the birth and parentage of medical electricity, and we have conducted it to within almost a hair’s breadth of our patient. The various methods of applying it will be considered in our next Lecture, which I trust, Gentlemen, to render more interesting; but the dry details we have been discussing are, I assure you, essential as a secure foundation for a practically useful survey of electro-therapeutics. FOOTNOTES: [1] See “Vital Motion as a Mode of Physical Motion.” By C. B. Radcliffe, M.D. Macmillan. [2] See Mr. Netten Radcliffe upon the differential reaction of voltaic and induced currents of electricity. Note to page 331, vol. i., of Bazire’s translation of Trousseau’s “Clinical Medicine.” Hardwicke.