Notice sur des Expériences exécutées avec la Machine Dynamo-électrique
et avec la Lampe á arc Voltaïque de M. Jürgensen

... . "Ill IS=aSSBSSII i liIII .„iJU, ,1, 16 From this it is seen that for currents in the field magnets varying from 14 to 26 amperes, the total electromotive force is nearly constant, which shows that for the smaller current the field magnets are already satiated. Hence less wire might advantageously be used on these magnets, producing a resistance less than l,i S. U., which, we are informed, was the resistance of the internal and external field magnets together; that of the revolving armature being, we were informed, 1,75 S. U. The greatest power electrically developed by the dynamo during the preceding experiments was 3,e horse- power, and the greatest horse-power usefully electri- cally developed, that is developed in the external circuit, was 2,4. We were not able to judge of the efficiency of the machine, that is the proportion of the horse-power elec- trically developed by the dynamo to that given to it by the steam-engine, because there was no transmission dynamometer available, or arrangements for taking indicator diagrams of the engine. It is most important, in order to judge of the commercial value of the Jürgensen dynamo, that dynamo- meter tests of the transmitted power should be made simultaneously with those of the electric power given out by the dynamo, or if time does not allow of a transmission dynamometer being obtained and fixed in position, that the cylinder of the engine should be bored for the insertion of an indicator, so that indicator diagrams may be taken simultaneously with the elec- tric tests.