166 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



induction flux, is constantly growing. If the core of a transformer is 

 very large the building-up time may be a minute or more, and the 

 phenomenon may then become very striking. 



The curve ONM (Fig. 10) represents graphically the flux of mag- 

 netic induction through the core as a function of the time. One 

 vertical unit of the figure corresponds to thirty thousand maxwells, 

 and one horizontal unit to a twentieth of a second. 



A hysteresis diagram for the transformer under investigation is 

 shown in Figure 11. The cycle corresponds to a maximum excitation 



TABLE VIII. 



of 4200 ampere-turns, and the results of measurements of the flux 

 changes in the core for this cycle are given in Table IX. From what 

 has been explained already, and the data given here one can predict 

 with accuracy the characteristics of the core, and the current curves 

 for this transformer, for any practical case within the limits of the 

 above excitation. 



