After the winding is completed the transformer is ready for assembling. The yoke pieces of the core should be slipped into position and the whole carefully lined up. The transformer itself is now ready for mounting. [Illustration: Fig. 185.—How to make a Tap in the Primary by soldering a Copper Strip to the Wire.] The base-board measures 11 x 7 3/4 x 7/8 inches. It is shown in Figure 192. The transformer rests upon two wooden strips, _A_ and _B_, 4 1/4 inches long, 1 1/4 inches wide, and 3/4 of an inch high. The strips are nailed to the base so that they will come under the ends of the core outside of the fiber heads. The transformer is held to the base by two tie-rods passing through a strip, _C_, 6 inches long, one-half of an inch thick and three-quarters of an inch wide. The strip rests on the ends of the core. The tie-rods are fastened on the under side of the base by means of a nut and washer on the ends. When the nuts are screwed up tightly, the cross-piece will pull the transformer firmly down to the base. [Illustration: Fig. 186.—The Transformer completely Wound and ready for Assembling.] The regulating switches, two in number, are mounted on the lower part of the base. The contact points and the arm are cut out of sheet-brass, one-eighth of an inch thick. It is unnecessary to go into the details of their construction, because the dimensions are plainly shown in Figure 188. The contacts are drilled out and countersunk so that they may be fastened to the base with small flat-headed wood screws. Each switch-arm is fitted with a small rubber knob to serve as a handle. The arm works on a small piece of brass of exactly the same thickness as the switch-points. Care must be taken that the points and this washer are all exactly in line, so that the arm will make good contact with each point. There are five points to each switch, as shown in Figure 190. [Illustration: Fig. 187.—Wooden Strips for mounting the Transformer on the Base.] The switch, _D_, is arranged so that each step cuts in or out twenty turns of the secondary, the first point being connected with the end of the winding. The second point connects with the first tap, the third contact with the second tap, the fourth contact with the third tap, and the fifth contact with the fourth tap. [Illustration: Fig. 188.—Details of the Switch Parts.] The switch, _E_, is arranged so that each step cuts in or out five turns. The contacts on this switch are numbered in the reverse direction. The fifth contact of switch _D_, and the fifth contact of switch _E_, are connected together. The fourth contact is connected to the fifth tap, the third contact to the sixth tap, the second contact to the seventh, and the first contact to the end of the winding.