THE narrow gauge Dolomites railway which joins Calalzo, in the Piave valley, to bbiaco, a distance of about forty miles, has now been working very satisfactorily for over two years. As the railway passes through Cortina d'Ampezzo, it is much frequented by tourists. The railway is operated by electricity and so there is no smoke and steam to detract from the beauty of the scenery. Fears were entertained in case, during heavy falls of snow, water would get into the motors and interfere with their working. A special arrangement was therefore devised for them so that when necessary they could be made ‘enclosed’ motors. Even in snow-clearing operations, when they were considerably overloaded, the motors suffered no damage. In the Brown Boveri Review for October, A. Brodbeck gives an account of the electric equipment of this railway. It receives its power from a three-phase network at Calalzo at a pressure of 18,000 volts; but for operating the railway, direct current at 2700 volts is adopted. This is done by the use of only one substation situated near Cortina, a little more than half-way from the power terminus. The conversion of the alternating to direct current is done at the substation by means of two mercury arc rectifiers each of 11,000 kilowatts capacity at 3000 volts. It is interesting to learn that a momentary load of 200 per cent does them no harm, and that they can withstand a 25 per cent overload for half an hour. Owing to the comparatively small currents they take, they require little space and their efficiency is extremely high, being 99.1 per cent over a large range of output. The use of rectifiers in railway plants is increasing, and we anticipate a rapid increase in the future.