258 



H. S. Carhart — Surface Transmission 



of the magnetometer, consisting of three pieces of magnetized 

 watch spring attached to the back of a plane mirror. This 

 small magnet was about one centimenter long; and, with the 

 attached mirror, was suspended by a cocoon fiber 10 cm long, 

 after the manner described by Gray.* The deflections were 

 read by a telescope and scale at a distance of l - 8 m , though this 

 distance varied somewhat in the different sets of experiments, 

 inasmuch as the only quantitative comparisons made were 

 between each pair of magnets used in the magnetizing spirals. 

 The maximum moments were usually attained at ten dis- 

 charges, the magnetization of the two rods being then pretty 

 nearly equal. 



After this nearly stationary condition had been reached, some 

 unexplained facts led to an exchange of the two magnets in 

 the spirals, keeping them turned so that a subsequent discharge 

 would still magnetize them in the same sense as before. A 

 single discharge of the Leyden jar then sufficed to increase the 

 magnetic moment of B from 50 to 60 per cent, and to diminish 

 that of A about half as much, as shown in fig. 1. This was 

 repeated many times with the same invariable result. Con- 

 tinuing the discharges the ordinates of both curves increased 

 as shown. After the magnetization of both rods had approached 

 an apparent maximum, therefore, the mere exchange of the 

 magnets in the spirals was followed by this striking result. 























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i 

























A 











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jo 





























\ 



































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g 











































































































































































































15 













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5 "TO is* 24 20 16 Vi 



Not finding any information guiding me to an explanation of 

 this curious behavior of the magnets, I sought it by an exami- 

 nation of the physical condition of the magnets themselves 

 after they had reached the maximum of magnetic moment with 

 ten discharges. The outside was gradually eaten away with 

 * " Absolute Measurements in Electricity and Magnetism," p. 6. 



