146 Crook — Electromagnetic Alternating Currents. 



readily detected with a telescope and scale. It was found that 

 an oscillation of the static charge in the "magnetic condenser" 

 produced a demagnetizing effect which could be readily 

 detected with the magnetometer. The effects were lacking 

 when a thin foil condenser was substituted for the iron one. 



The residual magnetism of the laminated electro-magnet 

 was also found to be affected by the oscillating electric charges, 

 when connected in series, fig. 3 B, with a condenser to the 

 terminals of the static machine. The amount of this effect 

 was approximately equal to the effect when the magnet was 

 used as a condenser. 



Fig. 4 



Another test, fig. 4, was made by placing a pile of these 

 japanned iron sheets between terminals of tinfoil which were 

 insulated from the iron by mica. This proved to be just as 

 effective in producing results as the other method. The 

 frequency of oscillation was an indeterminate factor and did 

 not seem to affect the results, as the demagnetizing effect was 

 apparently produced during the first oscillations. A single 

 spark between the terminals of the machine, in most cases, 

 proved to be as effective as a continuation of the oscillatory 

 discharges. 



Note.— This work was done at the University of Nebraska under the imme- 

 diate direction of Dr. D. B. Brace, and much of the success of the investiga- 

 tion was due to suggestions offered by Dr. Brace and by Professor B. E. 

 Moore. 



Physical Laboratory, University of Nebraska, 

 Lincoln, Nebr. 



