How to Use a Galvanic Battery in Medicine and Surgery / A Discourse Delivered Before the Hunterian Society, Third Edition

by Herbert Tibbits

F. Commutator of the poles. The poles, N and P, are seen through holes cut in the element board.

G. Key by which the current can be shut “off” or “on,” without change of position of the conductors. It can also be used by vibrating it backwards and forwards as an “interrupter.”

I, I. Binding screws, to which are attached the conducting wires and sponge-holders, &c.

The Voltaic Battery.

The Voltaic Battery (see [Fig. 6], p. 20) has its cells arranged in the interior of a mahogany case, and in use they are hidden from view and from danger, but I now partially expose them by removal of the tray for holding the sponges and accessories. Their connecting wires are brought across the under surface of the element board, which is made to move upon hinges that, when necessary, the cells may be examined, but at other times this element board is held in position by a bolt, and it should never be needlessly disturbed. These wires conduct the current through the graduating dial, and the position of the needle of this dial determines from how many of the cells the electricity shall be allowed to reach the binding screws, and from them, by way of the conductors, sponge-holders, or electrodes, the body of the patient,[8] or whether it shall be entirely shut off, as is the case when the battery is not in use, and when the needle stands at “0” ([Fig. 7]). When the needle points to any stud numbered on the dial, the number of cells marked on that stud are brought into action, and the needle is made just wide enough to touch one of the studs before it breaks contact with the preceding one, and thus the current may be increased or decreased in power without shock, and while the electrodes are held applied to the patient; but if it were not so made a series of painful shocks would be communicated whenever the current was increased or decreased. Should the needle, from forgetfulness, be left when out of use in any other position than at “0,” a guard upon the lid of the instrument prevents its being shut, and the operator has his attention called to his inadvertence. A Voltaic alternative, or change of direction of the current, is sometimes required in treatment, and the commutator of the poles enables this to be accomplished without alteration in the position of the conductors. By pushing forwards or backwards the handle which moves a lever working below the element board the current is instantly reversed, and the alternation of the letters “P” and “N” seen through holes cut in the element board indicates at once not only that there has been a change of poles, but which pole is at the moment negative or positive; whereas in all previous instruments, when the poles have been changed, there has either been no letter marking them, or this letter has really been wrong, and one has had to remember this; and under such circumstances, and examining patients in rapid succession, momentary confusion of the poles was very liable to occur, even to a practised operator. A key enables the current to be shut off or on without removal of the conductors. Dirt is a non-conductor of electricity, and the studs of the dial must be kept clean with emery paper or plate-powder, as also the under surface of the needle, key, and binding screws, which unscrew to admit of removal. In the daily use of a battery the chief work is usually thrown upon the first half (say in a battery of forty cells, upon the first twenty-five), and various arrangements have been added to batteries by ingenious instrument-makers to enable the operator to vary his selection of the cells to be brought into use, and thus to relieve the first half of his battery, or, in other words, to equalize its work. But this unequal work question is more a theoretical than a practical evil; for if the initial cells grow weaker a greater number can be placed in use. I have carefully studied all the proposed modifications, and have found in all of them the remedy worse than the disease, unless the graduating dial be doubled (an original suggestion of my own), so that the initial cells of one week may be made the terminal cells of the next.

Fig. 7. Graduating dial with needle at “0”.

When desired batteries can be constructed with this double dial [(Fig. 8)], but it adds to the complexity of the instrument, and I do not myself use it.

Fig. 8. New form of Graduating Dial.