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

18 At a speed of 930, with 8,7 ohms in the external circuit, the total efficiency of the machine was 0,7 7, and the useful or commercial efficiency 0,58, or nearly six-tenths of the total power given to the dynamo was reproduced electrically in a useful manner in the external circuit. In this latter case, a current of 14 amperes was sent through the external resistance of 8,7 ohms. Now, when two of Mr. Jürgensen’s lamps were in circuit we found the external resistance to be about 7 ohms and a current of about 14 amperes to give the best results after the lamps had been adjusted by the gentleman who represented the inventor. Hence under the ordinary conditions of burning the Jürgensen machine may be expected to have a total efficiency of about 0,8, and a useful or commercial effi- ciency of about 0,6 may be expected in the external circuit. A sample of some of the results obtained follows: Rates of power appearing use- fully in external circuit to power given to dynamo .... Rates of power given out by dynamo to power given to dynamo ____.................... Horse-power appearing in the external circuit............ Horse-power given out by dy- namo ..................... Horse-power given to dynamo by engine................. Total electromotive force pro- duced by dynamo in volts . . Electromotive force produced in the external circuit, in volts 0,44 0,54 0,58 0,58 0,85 0,93 0,84 0,77 2,4 2,6 2,c 2,4 4,5 4,6 3,7 3,1 5,3 4,9 4,5 4,i 141,6 150 160 165 73,8 88,2 109,8 124