To determine the direction of the current is sufficiently simple. Where a descending current is desired, the binding post which represents the electrode at the head of the tub must be connected to the positive pole of the battery, the other binding post to the negative pole; where an ascending current is desired, the reverse of this is done. The duration of the bath varies with different cases. The average is about twenty minutes, though the time may range from ten minutes to an hour and a half. Where it is desired to give the patient a galvanic shock, it is only necessary rapidly to reverse the current by means of the commutator. The simultaneous contraction of almost the ENTIRE muscular system that accompanies the reversal of a current of sufficient intensity in the bath, affords a striking illustration of the _general_ effects of the galvanic bath. In cases where paralyzed muscles have lost their faradic irritability, galvanic interruptions are almost indispensable to successful treatment. I have before (page 14) described a “surface board,” which I have devised for the purpose of localizing the current from one of the poles in any portion of the body where required. This proceeding should by no means be looked upon as a “local” method of electrization; on the contrary, it is just as much “general” as the ordinary electric bath. Whereas in local applications the current runs from one point of the body to another, in this case, supposing the spot where the surface board is applied to be the centre, and the rest of the body the periphery, a current runs between _every point_ of the periphery and the centre, its direction being centripetal when the surface board communicates with the negative, centrifugal when with the positive pole of the battery. The current is felt more or less intensely in proportion to the proximity to the body of the surface board. With the galvanic this is less noticeable than with the faradic current. When, for example, a faradic current of medium strength being employed, the surface board is held about six inches from the abdominal surface, little or no current is felt. Let the surface board be now gradually approximated to the abdomen, and the current will be felt more and more sensibly, until, when about an inch away from the skin, or touching this, its influence becomes so strong as to cause more or less energetic contractions of the abdominal muscles. Where the galvanic current is employed, the skin beneath the surface board will be found more or less reddened after a few minutes’ application; the burning sensation ordinarily accompanying galvanic applications will also be experienced more or less intensely, in proportion to the strength of the current employed.