The eight glow lamps forming one group are in many cases scattered in different streets, often quite out of sight of each other. Under such circumstances, the substitution of one light centre, however powerful, for every eight could only be done by leaving many spots in complete darkness. To give a usefully diffused light by means of arc lamps, their number would have to be considerably greater than ninety-two, or, in other words, the standard of street lighting would have to be raised, and for this the town was not prepared to pay. The business has now passed into the hands of the Anglo-American Corporation of London, who are extending the installation by placing alternating current dynamos at the station to work transformers for the supply of houses so as to utilise the original plant for street lighting only, as, even with the advanced knowledge of the present day, it is doubtful whether for this purpose a more economical system could be employed. CLASS V. THE DISTRIBUTION WITH SECONDARY BATTERIES, OR THE BATTERY TRANSFORMER SYSTEM. Mr. Lane Fox was the first to put forward a complete system of electrical supply on this plan, Fig. 23. [Illustration: FIG. 23. G Generating station. A Accumulators (secondary batteries). R Returns. M Mains or conductors. L Lamps. X Meters. ] The system is discussed by him as follows:[4]— “The chief points of the system is the use of a generator in a central position, from one pole of which insulated conductors or mains are led to the several points where the electric energy is to be utilised, being branched and sub-branched as much as required, and thence back to the other pole of the generator by an uninsulated conductor, such as the gas or water pipes. At certain points, storage or secondary batteries are set up in connection, on one hand, with the mains, sub-mains, and branches, as the exigencies of the case may require, and, on the other, with the return conductor.” [4] Hedges on the Supply of Electricity by Local Authorities. Proceedings of Association of Municipal and Sanitary Engineers and Surveyors, vol. ix. (1882-83), p. 159. “The combination of generators, circuit and storage batteries is such, that when the current from the generators falls below the demands made on it from the various outlets to the mains at which its energy is utilised, the deficiency is made up from the storage batteries, which act in unison to supply the requisite quantity of energy. On the other hand, when the current from the generator exceeds in point of quantity the demands upon it at the various outlets, the excess goes to charge the storage batteries and to create a reserve to be called upon in case of need.”