These explanations being understood, there remain but few things to be said to cause the operation of the hammer to be thoroughly comprehended. The elementary sections constituting the electric cylinder, A B, of the hammer are 80 in number, and form a total length of one meter. Their ingoing and outcoming wires end in a collector of circular form shown at F G. The brushes are replaced by two strips, C E and C D, fixed to the double winch, H C I, which is movable around the fixed center, C. They can make any angle whatever with each other, so that by trial there maybe given the active solenoid the most suitable length. When such angle has been determined, the angle, E C D, is rendered invariable by means of a set screw, and the apparatus is maneuvered by imparting to the double winch, H C I, an alternating circular motion. The iron cylinder weighs 23 kilogrammes; but, when the current has an intensity of 43 amperes and traverses 15 sections, the stress developed may reach 70 kilogrammes; that is to say, three times the weight of the hammer. So this latter obeys with absolute docility the motions of the operator's hands, as those who were present at the lecture were enabled to see. I will incidentally add that this power hammer was placed on a circuit derived from one that served likewise to supply three Hefner-Alteneck machines (Siemens D{5} model) and a Gramme machine (Breguet model P.L.). Each of these machines was making 1,500 revolutions per minute and developing 25 kilogrammeters per second, measured by means of a Carpentier brake. All these apparatus were operating with absolute independence, and had for generator the double excitation machine that figured at the Exhibition of Electricity. In an experiment made since then, I have succeeded in developing in each of these four machines 50 kilogrammeters per second, whatever was the number of those that were running; and I found it possible to add the hammer on a derived circuit without notably affecting the operation of the receivers. It results from this that with my system of double excitation machine I have been enabled to easily run with absolute independence six machines, each giving a two-third horse-power. The economic performance, e/E, moreover, slightly exceeded 0.50. * * * * * SOLIGNAC'S NEW ELECTRIC LAMP.