Louis Bell, 1911 Encyclopædia Britannica (1911)
“ Torque, neglecting field distortion, is at a maximum when the current is the greatest possible at the given applied voltage—that is, when the motor is at rest. With a small armature resistance this current is generally far too great for convenience; hence the motors are usually started with a rheostat in series with the winding if the current is not limited by the generator itself. The torque then depends on the sum of the resistances in circuit, and can be made just sufficient to start the motor under the required load. ”
