continuous current machines, the circuits from which are joined to a regulating apparatus, which by altering resistance keeps the electro-motive force of the large machines proportional to the number of lamps which are to be maintained. At present hand regulation is employed, but it is proposed to use automatic regulation, which will increase the life of the lamps, as they are severely tried by the variation of the current, which is more noticeable than in continuous current installations. The current from the machines is at a potential of 2400 volts, and that from the transformers is 100 volts. The primary wire which carries this high electro-motive force does not enter the houses, as the transformers are, as a rule, fixed in the cellars, and from them the house branch is led in the form of a cable of fine wires, having a total diameter of 7/16 inch; the lamps, which are placed in parallel across this cable, are attached to single No. 18 or No. 20 B. W. G. wires in the usual manner. When first established, the transformers presented an element of danger, in that they, in common with all induction coils, were also condensers, and therefore a dangerous shock might be given to any one touching some unguarded portion of the lighting system. This has been prevented by the simple plan of connecting one of the terminals of every secondary circuit to earth, a method which, however, is not to be recommended, as it throws an additional strain on the insulation of the primary circuit; in fact, by earthing the secondary the insulation is practically reduced to one-half. A safety device should be inserted, which would come into operation on any leakage from primary to secondary, and immediately cut out the transformer. The primary-current conductor is led overhead, and still remains an objectionable feature of the system, although the original trouble with the neighbouring telephones and telegraphs has been overcome. The primary circuit is a small carefully insulated cable of high conductivity copper wire, nineteen strands of No. 15 B. W. G. It weighs about 1¾ ton per mile, and is suspended, where it crosses the streets, on a steel bearer whose tensile strength is 1⅕ ton. It is so arranged according to the droop of the cable that the strain of the bearer never exceeds 225 lbs., which means that the factor of safety is nearly 12 to 1. Double cut-outs or safety fuses, in many instances of the author’s design, are placed on each pole of the primary, at the point where it enters the house, so that, in the case of an excess current, the mica-foils would fuse, and all connection between that house and the supply main would cease.