658 RECORDS. 



Summary of Papers. 



M. I. Pupin and S. G. F. Townsend, The current wave in 

 a transformer with open secondary circuit is a complex harmonic 

 vibration, and the object of the research is to determine the am- 

 plitudes and phase relations of the components of the funda- 

 mental vibration. 



The component due to eddy currents is determined from the 

 curves of electromotive force and current, together with the static 

 hysteresis loop for the given magnetization, by a graphical 

 method. The eddy current component is found to lag behind 

 the electromotive force. Also, the dynamic hysteresis loop is 

 shown to have a rounded point, as distinguished from the sharp 

 point characteristic of the static loop. 



The phase of the fundamental of the total current is found by 

 means of a specially constructed phase-meter. Its amplitude is 

 determined from the electromotive force and total watts. 



The remaining component to be determined is that due to hys- 

 teresis and induction reaction. This and the eddy current com- 

 ponent form two sides of a parallelogram of which the funda- 

 mental of the total current wave is the diagonal. If the last two 

 are determined in amplitude and phase, the fundamental of the 

 distorted wave of magnetizing current can readily be found. 



The ultimate object of the investigation is to formulate the 

 laws which govern the reactions accompanying the magnetiza- 

 tion of iron by alternating currents. 



C. C. Trowbridge. Calcium sulphide, made phosphorescent 

 by exposure to sunlight at ordinary temperatures, was made 

 non-luminous by immersion in liquid air. Then when allowed 

 to heat up gradually to normal temperature, the phosphorescence 

 again became visible at about — ioo° to — 75 ° C. The same ma- 

 terial, if exposed to sunlight while immersed in liquid air, phos- 

 phoresced faintly while still immersed. When exposed to the 

 electric arc it phosphoresced strongly. In both of these cases 

 the phosphorescence became brighter when the temperature 

 was raised. From these results and what was previously known, 

 it was concluded that when a phosphorescent substance, like cal- 

 cium sulphide, is excited by light, the phosphorescent energy will 



