816 REPORT— 1886. 



second difficulty was to prevent heating at the circumferential contact. A whole 

 year was wasted in experiments on carbon contacts, which led' to no results, and 

 the author now proposes to run at a low speed and to use several brush contacts 

 on the circumference, so arranged as to be easily accessible. This will surmount 

 every difficulty. 



In conclusion the author drew attention to the fact that the only reason why 

 electric lighting is not cheaper than gas is that the machines, plant, and attendante 

 are in use on an average only three or four hours per day. The electricity at any 

 moment which could be generated, but which is not used, is a waste product. If 

 this were used for the production of copper utensils, and the reduction of argenti- 

 ferous copper ores and such purposes, the electric light could be supplied from 

 central stations at less than the cost of gas and return a handsome dividend to the 

 undertakers. 



9. Ow Distributing Electricity by Transformers. 

 By Charles Zipernowsky. 



Aft€r a brief reference to the several attempts that have been made to over- 

 come the difficulties in the way of lighting a considerable area by means of 

 electricity since the subdivision of the electric light has become an accomplished 

 fact, the author pointed out that a practical system of distributing electric energy 

 over a large area can only be based upon the use of high tension currents for 

 conveying the energy from the generating centres, in combination with some mode 

 of reducing the high tension to the limits of diiierence of potential which can be 

 made use of without danger or difficulty. This limit is at present about 100 volts. 

 Many methods have been suggested for meeting these conditions. 



Thus a counter electromotive force can be introduced into the high tensioa 

 circuit, as in the case of accumulators, and the terminals of such a device connected 

 with the lamps, &c. The cost is, however, a grave defect of this system, and the 

 high tension current which exists at each lamp might lead to fatal consequences. 



After referring to the electric transmission of power as another means of over- 

 coming the difficulty, the author discussed the use of induction coils or 'trans- 

 formers ' in some detail, tracing their use in the first instance to C. W. Harrison. 

 in 1857. Among subsequent workers Jablochkoff, C. T. Bright, Fuller, Varley, 

 Haitzma Enuma, Gaulard, and Gibbs were mentioned ; and he pointed out that the 

 want of success was in great part due to the fact that the transformers were con- 

 nected up in series, an arrangement which is only suitable for use with an invariable 

 number of lamps in any one secondary circuit, or when each transformer supplier 

 only one lamp. 



Besides considerations in regard to cost, the conditions to be satisfied by a 

 system of electric distribution were stated as follows : — 



(1) Perfect independence of the several consumption devices. 



(2) Absolute and relative economy so that the consumption of energy is in 



proportion to the number of lamps in use. 



(3) All regulation to be concentrated at one central station. 



The author then proceeded to describe the method he has devised in conjunction 

 with M. Max D4ri, and, with the assistance of M. O. T. Blathy, to satisfy the above 

 conditions. 



This is based on the fact that, with a constant primary tension, the secondary 

 one will vary only in proportion to the internal resistances of the coils ; and as the 

 resistance of each coil is less than 1 per cent, of the external resistance, the 

 secondary tension will not vary more than 2 per cent., whatever be the intensity 

 of current supplied to the consuming device. Constancy in the primary tension 

 at the transformer terminals is secured by connecting them in multiple arc with 

 the main fine, and the arrangements are such that current and tension are distri- 

 buted in the primary circuits, much as in a low tension direct supply system, the 

 transformers simply acting as tension-reducing devices. 



Instead of the old Euhmkorff coil pattern of transformer a form is adopted 



