Taking account of these fluctuations, it is not possible to see how, as Mr. Roux says with justice, a distribution of current by this system can be made in an efficient manner. Mr. Gaulard in his reply, virtually assents to this article, but adds, that these variations could be prevented, if the cores of the transformers be shifted either by hand or automatically. Both methods would be expensive, and, besides, the automatic regulation would be unreliable. ───┬───────────────────┬──────────┬───────────────────┬─────────── │ │ External │ │ │ │Resistance│ │ No.│ Primary │ of │ Secondary │Efficiency. │ Circuit. │Secondary │ Circuit. │ │ │ Circuit. │ │ ───┼─────┬─────┬───────┼──────────┼─────┬─────┬───────┼─────────── │ Δ │ I │ I Δ │ W. │ Δ │ I │ I Δ │ Δ 1 │ 23·4│12·13│ 283·84│ 1·24 │ 15·0│12·02│ 180·30│ 63·52 2 │ 31·4│12·13│ 380·88│ 2·00 │ 24·0│12·00│ 288·00│ 75·62 3 │ 53·0│12·13│ 642·89│ 3·80 │ 45·0│11·83│ 532·35│ 82·81 4 │ 70·0│12·13│ 849·10│ 5·50 │ 65·0│11·75│ 762·45│ 89·80 5 │ 93·0│12·13│1128·09│ 7·53 │ 87·0│11·58│1007·46│ 89·31 6 │107·0│12·13│1297·91│ 9·00 │102·0│11·31│1153·62│ 88·88 7 │126·0│12·13│1518·38│ 10·60 │119·0│11·13│1324·77│ 86·66 8 │145·0│12·13│1758·85│ 12·60 │138·0│10·95│1511·10│ 85·35 9 │159·0│12·13│1928·67│ 14·15 │156·0│10·76│1678·66│ 87·03 ───┴─────┴─────┴───────┴──────────┴─────┴─────┴───────┴─────────── It was at once recognised by all those interested in the subject, that this system made possible a subdivision, but by no means a distribution of current. Before proceeding further with the history of the development of the transformer, let us for a little while take up the question, what conditions are necessary for a practical and rational system of current distribution by means of transformers. As we have already explained in another part of this paper, the method of parallel connection, i.e., a system in which the difference of potential is held constant, is alone suitable. Depréz maintained in his time that the difference of potential between the terminals of the source of current must be kept constant. Should the distribution be made on this principle, the resistance of the network of leads must be very small, in order that with full load only a very small loss of electromotive force may take place in the leads. In the indirect system of current distribution, consequently, the tension at the secondary terminals of the transformers must also be maintained constant.