23,817. British Thomson-Houston Co., [General Electric Co.]. Nov. 3. Motors, controlling.-Relates to a control system for electric railways &c. whereby compensated series motors may be operated on either alternating or direct current. As shown in Fig. 1, each of the four motors M' to M<4> has an armature winding A', field winding F', F', and compensating-winding C', C'. Either the motor can be connected with all three windings in series to a source of direct current, or the compensating-winding C<1>, C<1> is connected to a source of alternating current and the two other windings F<1>, F<1> and A<1> are short-circuited in series with each other. The speed of the motor is controlled by means of a variable resistance Rin the armature circuit. The connections for a single motor with the windings all in series for direct current are shown in Fig. 2, d, d' being direct-current and a, a<1> alternating-current mains, F the field winding, R the variable resistance, C the compensating- winding, and s a reversing-switch. On opening the switch S and closing the switch S', the compensatiog-winding C is connected directly across the mains, and the armature, field winding F, and resistance R are connected in a closed circuit. A single resistance R may be used to control several motors, in which case, for direct current the motors are connected in parallel between one main and one terminal of the resistance with the three windings of each motor in series, and for alternating current the compensating-windings are connected in series in one main and the field and armature windings of each motor are in series and are short-circuited in parallel with those of the other motors through the resistance. These connections are made by the controlling-switch E, Fig. 1. Separate switches may be used, as in Fig. 2, for connecting the motors for alternating or direct current and for varying the resistance in circuit. G is a reversing-switch. When the leftband set of contacts is in engagement in the switch E, circuit is made for the alternating current from the main a through the contacts e<2>, e<3>, compensating-winding C<1>, C<1>, contacts e<17>, e<22>, compensating- winding C<2>, C<2>, contacts e<15>, e<23>, compensating- winding C<3>, C<3>, contacts e<13>, e<21>, compensating- winding C<4>, C<4>, and contacts e<11>, e<1> to the main a'. The four compensating-windings are therefore connected in series in the line, and the upper commutator brushes are connected through the contacts e<12>, e<14>, e<16>, e<18>, and e<9> to one terminal of the resistance R, the other terminal of which is connected through the reversing-switch G, field windings F<1> to F<4>, and reversing-switch G to the lower commutator brushes.