OX TRANSIENT ELECTRIC CURRENTS. 



.ill.) 



To .study the effect of longitudinal tension upcn the current, 

 loads of 4 and 8 kg. were successively applied, and the reading of 

 the galvanometer magnet measured by reversing the magnetizing 

 force. The effect of loading was simply to reduce the cunvni by 

 a small amount, and the representative curves were not greatly 

 altered. 



The above result leads me to suspect that possibly Matteueci 

 made a mistake in determining the direction of the current in 

 relation to the twist and field, always in such experiments somewhat 

 of a confusing matter. The main difference between the experiments 

 of Matteueci and those of later investigators lay in the thickness of 

 the bar or wire. Matteueci used mostly an iron bar 6.5 mm. thick, 

 while in the present investigation, the thickest wire experimented on 

 had a diameter of only 2 mm. Accordingly, I determined to repeat 

 the experiment of Matteueci with a soft iron bar 5.6 mm. thick and 

 2S cm. long. This was tested both by sudden twisting and by 

 reversing the direction of the magnetizing force. The arrangement 

 for twisting the bar was different from the one described above. It 

 was twisted by means of a lever, into the details of which E need nor 

 here enter. 



