A new point in the diagnosis of Graves' disease / by R. Norris Wolfenden.

  • Wolfenden, Richard Norris.
Date:
[1887]
Catalogue details

Licence: Public Domain Mark

Credit: A new point in the diagnosis of Graves' disease / by R. Norris Wolfenden. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    The method of applying the dose of electricity to the patient is indicated here: Fig. 2.—Patient with, one electrode on the nape of the neck, the other on the top of the sternum. G, galvanometer. B, constant current battery. If any number of healthy people are examined by the method indicated, it will be found that the body resistance to the passage of a moderate current of 15 volts EMF, will register about 5000 ohms. Occasionally one obtains 4000 ohms, sometimes it is much more than this, but the average may be taken at 4000— 5000 ohms. This I have determined on some fifty persons, in health, or with slight throat complaints. One may regard any- thing approaching 3000 ohms as low, and 2000 ohms as very low, and 1000 ohms as remarkably low resistance. The resist- ance of the healthy body to the passage of a current of about 15 volts EMF is really very great, and very little passes through the system. as a patient's body or the 1000 ohm coil, the increased current given by a large cell will not be of any advantage over that given by a small one ; so that, in test- ing with the 1000 ohm coil or acting upon a patient, it will be at once seen that a large cell gives no more current than the smaller one, owing to the large exter- nal resistance. Provided then with a coil of 1000 ohms and a galvanometer showing the cuiTent in milliampferes, we are able to test any battery without any calculation, because according to Ohm's law—C -^ R = E,— C being cur- rent, E, resistance and E, electromotive force. Suppose our galvanometer to give a deflection of 'OOIS ampere (1 '5 niilliampk-e) with our resistance coil of 1000 ohms, then '0015 x 1000 = 1-5 EMF in volts, in other words the electro- motive force of the current in question is 1 5 volts. Every battery should be tested before application, and the current accurately estimated.