313 



The residual excitation, or power which remains after ex- 

 citation has ceased, is always of the same amount, 130.68, if 

 that would have passed half the maximum ; below that it 

 bears a continually increasing ratio to the full power till it be- 

 comes two-thirds of it. If, while the magnet is in this state, 

 a current that would of itself produce the same lift be passed, 

 the effect is not doubled, but only increased by one-third. A 

 negative current, if powerful, destroys this condition ; if feeble, 

 only lessens it. 



The least current which he has tried, 0.0008, excites the 

 magnet, and even changes its residual magnetism. 



