The greatest merit of Faraday was that he stated idea about an electric and magnetic field. It could not develop mathematically these ideas, and in its monumental work "Pilot studies of electricity" are not present any equation! However Faraday's ideas formed the basis of the equations of Maxwell. Later Einstein said that in electromagnetism development Faraday in relation to Maxwell – the same that in development of mechanics Galilei in relation to Newton.
For removal of current of a the collector brushes representing the brass plates which were densely adjoining to a in appropriate They united to car, from where the direct current came to an external chain. The wire going to one of clips, besides, a winding of electromagnets. The simplest connection of the generator with of an electromagnet could be received, having connected one end of a winding of an electromagnet to one of collector brushes, for example the negative. the end of a winding of an electromagnet was connected to a positive brush. At such connection all current of the generator passed through electromagnets.
In process of increase in power of generators there was a new problem — how to remove current from the rotating anchor with the smallest losses. The matter is that at big currents of a brush started sparking. Except big losses of the electric power, it made harmful effects on work of a. Then the Gram counted rational to return to the earliest of the electric generator applied in Piksiya's car: he made an motionless, and forced to rotate electromagnets, after all it was simpler to remove current from a motionless winding. It placed anchor coils on an iron motionless ring and forced electromagnets to rotate in it. coils he connected among themselves so that all those coils which were exposed to identical action of electromagnets at present, are connected consistently. Thus the Gram broke all coils into some groups and each group used for bringing of current in an independent chain. However was to feed the electromagnets exciting current with a direct current as alternating current could not cause in them invariable polarity. Therefore at each generator of current it was necessary to have the small generator of a direct current.