Armatures are wound with a number of turns of wire in each coil, unless the machine is very large, and present an appearance more like Fig. 12. In this figure the brushes are arranged to make contact with the outer surface of the ring _C_, which is the commutator. The segments _s s_ are connected with the ends of the armature coils _c c c_, but are separated from each other by some kind of material that will not conduct electricity--that is, they are electrically insulated. As will be noticed from this, the armature in Fig. 11 acts as a commutator as well as an armature, its outer surface performing the former office. In the winding the difference between Figs. 11 and 12 is simply in the number of turns in each coil, there being one turn in Fig. 11 and several in Fig. 12. [Illustration: FIGS. 11, 12.--DIAGRAMS ILLUSTRATING THE METHOD OF WINDING ARMATURES OF ELECTRIC MOTORS AND GENERATORS.] The armature shown in Fig. 10 is of the type called drum armature, but it can be wound so as to produce the same result as the ring, although it is not so easy to explain this style of winding. It will be sufficient for the present explanation to say that whatever type of armature may be used, the winding is always such that the direction of the current through the wire coils is reversed progressively, so that the magnetic polarity is maintained practically at the same point; therefore there is a continuous pull between this point of the armature core and the poles of the field magnet. The commutator is secured to the armature shaft, and the brushes through which the current enters and leaves are held stationary; keeping this fact in mind, it can be seen at once that in Fig. 12 the current will flow from the brush _a_ through the two sides of the armature wire to brush _b_, hence all the coils on the right of the vertical line will be traversed by the current in the same direction--that is, either to or from the center of the shaft--and in the coils on the left the direction will be opposite, which is just the same order as was explained in connection with Fig. 11. [Illustration: FIGS. 13, 14.--DIAGRAMS ILLUSTRATING THE DIFFERENCE BETWEEN AN ELECTRIC MOTOR AND A GENERATOR.]