I am aware that it has been said by some of our practitioners, with, if I rightly remember, the able discoverer of the grand practical principles of our system, Prof. C. H. Bolles, at their head, that it is not quite prudent to use the negative pole in hand for diagnosis, lest we possibly contract the disease from the patient; since, in that case, the current runs from the patient to the practitioner. They think it safer to use the positive pole in hand; so letting the current run from the practitioner to the patient. There is force in this consideration, without doubt, where the patient is affected with a poisonous or malignant disease. And where any thing of this nature is apprehended, I would never examine with the negative pole in hand. But these cases are commonly so manifest, or so easily determined by colloquial inquiry, that examination with the electric current is rarely if ever necessary. And when the disease is plainly not of a poisonous or infectious nature, I do not think there is any danger to be apprehended from the cause stated. I therefore prefer, as a general rule, to examine with the negative pole; and for the reason given above. The temperature of the room and the adjustment of apparel should be the same as for treatment. To prevent improper chilliness, the room ought to be of such temperature that clothing is not required for bodily comfort--say, from 70 to 80 degrees, _Fahrenheit_. Seat the patient on a stool or chair, (a stool is most convenient), and yourself at his side, with your machine, ready for use, on a table or bench before him, and a vessel of warm water within easy reach. If the patient be a man we let his trunk be disrobed, giving free access to the back, chest and abdomen. If the patient be a woman, let her be covered with a treating-robe, of which garments the practitioner should keep a supply. They are made much like a lady's plain nightgown; but large and loose, so as to serve ladies of any size, and give ample room to work the electrodes under them. Her skirts should be dropped _below the seat_, so far that their bands shall lie across her lap.