. Bulletin. Science. Figure 67.—Gramme's magneto as provided with Jamin's compound magnets. From H. Fontaine, Eclairage a I'electricite, Paris, 1877, p. 104.. 6-disk Alliance machine. The voltage was equal to that of 105 normal Bunsen cells, and the current was equal to that of 5 such cells. Roughly speaking, such power implied an efficiency of 50 percent. The cost of the machine was £400 in England. Arc-light demonstrations were made in the new Clock Tower of Parliament in London in 1873, but since the machine was quite apt to overheat the arc lights were discontinued in favor of gas.^* At th

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. Bulletin. Science. Figure 67.—Gramme's magneto as provided with Jamin's compound magnets. From H. Fontaine, Eclairage a I'electricite, Paris, 1877, p. 104.. 6-disk Alliance machine. The voltage was equal to that of 105 normal Bunsen cells, and the current was equal to that of 5 such cells. Roughly speaking, such power implied an efficiency of 50 percent. The cost of the machine was £400 in England. Arc-light demonstrations were made in the new Clock Tower of Parliament in London in 1873, but since the machine was quite apt to overheat the arc lights were discontinued in favor of gas.^* At th Stock Photo
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. Bulletin. Science. Figure 67.—Gramme's magneto as provided with Jamin's compound magnets. From H. Fontaine, Eclairage a I'electricite, Paris, 1877, p. 104.. 6-disk Alliance machine. The voltage was equal to that of 105 normal Bunsen cells, and the current was equal to that of 5 such cells. Roughly speaking, such power implied an efficiency of 50 percent. The cost of the machine was £400 in England. Arc-light demonstrations were made in the new Clock Tower of Parliament in London in 1873, but since the machine was quite apt to overheat the arc lights were discontinued in favor of gas.^* At th
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. Bulletin. Science. Figure 67.—Gramme's magneto as provided with Jamin's compound magnets. From H. Fontaine, Eclairage a I'electricite, Paris, 1877, p. 104.. 6-disk Alliance machine. The voltage was equal to that of 105 normal Bunsen cells, and the current was equal to that of 5 such cells. Roughly speaking, such power implied an efficiency of 50 percent. The cost of the machine was £400 in England. Arc-light demonstrations were made in the new Clock Tower of Parliament in London in 1873, but since the machine was quite apt to overheat the arc lights were discontinued in favor of gas.^* At the beginning of 1874, Gramme cut down the size and considerably increased the efficiency of both the high-resistance and low-resistance generators by relying completely on the principle of self-excitation.'" The new model, called the type d^atelier (figs. 65, 66), reduced the number of armatures to one and reduced ''^ Engineering, 1873, vol. 15, pp. 291-292. " Z. T. Gramme, "Sur les Nouveaux Perfectionnements apportes aux machines magneto-electriques," Comptes rendus, 1874, vol. 79, pp. 1178-1182; ,\lfred N. Breguet, "Machine magneto-elecfrique de M. Gramme," Revue industrielle, 1874, vol. 3, pp. 405-410; Engineering, 1874, vol. 18, pp. 412-414. the number of electromagnets necessary to supply the field. The electromagnets were still cylindrical in form but were placed horizontally, with one above the other, as in the original Ladd generator. The axis of the single armature was horizontal and in the same vertical plane as the electromagnets instead of being perpendicular as in the Ladd machine. As before, the magnetic circuit was completed by cast-iron plates at the ends. Other changes made it possible to increase the speed of rotation without excessive heating of the armature. One electrochemical model and two arc-light models were now produced. The electrochemical machine (fig. 65) weighed 177.5 kg., measured 0.55 meters square by 0.60 meters h