The carbons having now been fitted in their beds, the distal end (coil) of the head wire is placed beneath the carbon, and the wire itself continued up along the vertical groove to either one of the gimlet holes. Through this, from within outward, the proximal end of the wire is now drawn and left for the present. The distal end of the second wire having now been placed beneath the carbon at the foot of the tub, this wire is continued up through the vertical groove, along the upper edge of the foot of the tub to the side nearest the binding post to which the wire is to be attached, along the groove on the upper edge of this side to the head of the tub, and thence to the respective gimlet hole, and through this, from within outward. The wires being now all in position, all the coping is next screwed or nailed down firmly, care being taken that the screws or nails used for this purpose do not injure any of the wires. The coping fastened down, the binding posts are now screwed down in the sites previously marked out for them. Before they are screwed _entirely_ down, the denuded portion of the proximal end of each wire is securely wound around the screw of the respective binding post, and the posts are then _firmly_ screwed down, holding the proximal ends of the wires in place. Connection is now established between the binding posts and the head and foot electrodes respectively. The vertical grooves are now to be filled in with putty and painted over, care being taken to keep the carbon free from paint. The last step towards completing the apparatus is to fasten the carbons in their beds. The simplest way of doing this is by stretching over each carbon a piece of muslin, folded double, and tacking this down around the edges. Zinc or galvanized iron tacks are best. Copper tacks should be avoided on account of their superior conductivity.
In order to be able when required to localize the current in special portions of the body, it is well to be provided with what I have termed a “surface board.” This is a piece of black walnut, say 14 in. long by 5 in. wide, ¾ thick, having in the centre a bed to accommodate a carbon plate, say 5 in. long by 2 in. wide, ¼ thick. From the centre of this bed a gimlet hole pierces the board. The denuded end of an insulated wire is drawn through this gimlet hole from without inward (toward the bed) and twisted in the form of a spiral to prevent its slipping back, as well as to insure its more certain connection with the carbon. The carbon is now placed in the bed, and kept there by a piece of muslin drawn over it and tacked down. The wire should be of sufficient length to reach the battery. I shall speak further on of the use to be made of the surface board.
