6 Ash WORTH, Mouent and lincrgy of a llbrattng Magnet. 



Assigning to a a series of values from o to 90^ the 

 relative mean values of the magnetic moment and energy 

 may be calculated. In the subjoined table, columns (3) 

 and (4), the maximum in each case has been put equal to 

 100. 



The principal difference between this and the former 

 set of numbers is the absence here of negative values 

 and consequently of diamagnetic properties. The mag- 

 netic moment declines continuously, but the energy 

 reaches a maximum at an angle « approximately equal 

 to 70'. At 90 the magnets are in a position of 

 instability, if such a pair of magnets is in rotation the 

 magnetic moment vanishes. 



The behaviour in the simple case here considered of 

 two magnets vibrating freely presents some features which 

 are found in the behaviour of a ferromagnetic substance 

 when its residual [magnetism is subjected to rise of 

 temperature. There is in such a substance a decline of 

 magnetic moment which at lower temperatures is slow 

 and at higher temperatures swift, and at or near the 

 critical temperature, where the loss of magnetism is very 

 rapid, the phenomenon of recalescence is found, which 

 shows that the rate at which energy is being absorbed on 

 heating and emitted on cooling is extremely large. 



Sir J. A, Ewing conjectures that recalescence may be 

 due in part to the subsidence of rotations of molecular 

 magnets into vibrations of narrow range, and the table 

 shows that the change of energy is very large immediately 

 below 90 , when rotations pass into vibrations. 



