An important installation at Tours of 3500 lamps has been for some time successfully working. Another at Tivoli has some additional points of interest, in that the natural power of a waterfall is applied to generate electricity. Two turbines constructed by Escher Wyss, of Zurich, having an available head of 29·75 feet, give 80 horse-power each, which is employed to drive two Siemens alternating current dynamos, separately excited by two small continuous current machines. Two distinct circuits of chromo-bronze naked wire, 3·7 millimetres in diameter, are run overhead, in the same manner as telegraph wires, through the town for a total length of about nineteen miles. The street lamps are fixed alternately on each circuit, so that one-half can be extinguished at a late hour without interfering with the others, or having to turn out individual lamps. The number of lamps used in the streets is two hundred glow lamps of 50 candle-power; also one hundred and twenty glow lamps of 16 candle-power for the illumination of the narrower streets. Arc lamps are also employed, as well as a large reflector lamp, the rays from which are turned on the Temples of Vesta and Sibilla. A house-to-house system is also being established, and the company which has put up the work proposes to utilise the falls of Tivoli in order to transmit 2000 horse-power for lighting purposes in Rome. * * * * * The firm of Ganz, of Budapest, who are the manufacturers of the Zippernowsky-Deri-Blathy system of transformers, have a similar installation completed in order to light a portion of Lucerne. The water power of Thorenburg 3·1 miles off, works the turbines, which drive two self-exciting alternating current dynamos of the Ganz type, similar to those shown at the Vienna Exhibition in 1884. The primary current of 38 ampères, at an electro-motive force of 1800 volts, is led by four uncovered wires, each six millimetres in diameter, to the first station, which is 2·4 kilometres distant; here 1500 watts are taken off, and at 2·3 kilometres further 7000 watts are utilised in two of the hotels at Lucerne. A large installation on the same system has been put down in Rome, and several Continental cities are adopting this method of supplying electric light by small overhead wires. An advantage claimed by the Zippernowsky system is the method of keeping the strength of the magnetic field of the dynamos in accordance with the external demand for current. The regulating apparatus employed consists of a small transformer, the primary coil of which is traversed by the whole, or by a proportionate part, of the main circuit, while the secondary coil is inserted into the exciting circuit. Thus, if the main current increases, the exciting current induced in the two armature coils of the dynamo is reinforced by the inductive action of the regulating transformer; and the field of the dynamo is strengthened when more current is required.