ON Tuesday evening, April 11, the public thoroughfare stretching between Hatton Garden and the Old Bailey was lighted for the first time by the electric light. The novelty of the installation was the fact that the incandescent system had been adopted in preference to the arc system. Mr. E. H. Johnson, the agent of the Edison Electric Light Company, has in fact made a public demonstration of the Edison system by lighting up a district of London in the same way as by gas. In addition to the street lights, the different premises lining the street are also lighted; for example, the City Temple Church, Messrs. Negretti and Zambra's, Messrs. Spiers and Pond's. In all there are 936 incandescent lamps, and these are fed by one of the large dynamos stationed at No. 57, Holborn, the distributing centre of the company. These large generators are made upon the same plan as the smaller ones recently described by us, and are driven by Porter engines. They yield a current of 1025 amperes. The resistance of each lamp white-hot is 140 ohms, and as this is much greater than the hot resistance of other incandescent lamps,. the resistance of a long circuit is not so relatively high as in other systems, and hence there is less need of large leads. The cost of copper for conductors is an important item in electric lighting, but should copper conductors become too expensive to use, Mr. Edison intends to employ iron, say old iron rails. Mr. E. H. Johnson states that the company intend to manufacture and supply electricity for all kinds of purposes, and judging from experience gathered in New York, where a district is lighted by this system, the profits from the sale of electricity for power purposes alone will pay the company's dividends, so that they can afford to give the light for nothing. This remark is a rejoinder to those who argue that the gas companies will successfully compete with the electric light, because the profits from their waste products will pay their dividends. The Holborn street lamps each contain two of Edison's bulbs suspended from a cross bar running through the top of the lantern. The light is of a golden tinge like gas, but much purer, brighter, and. steadier. The lamps were switched on and off with the greatest ease, and altogether the experiment was a complete success.