STRAIN ON THK PHYSICAL PROPERTIES OF MATTKR. 



MAGNETISING solenoid not excited. 



Thus it appears that, whether the subsidence in 52 or in 20 vibrations be considered, 

 the internal friction is very perceptibly greater when the solenoid is excited than 

 when it is not,* and that the difference is greater, the greater the mean amplitude of 

 vibration. 



Experiment XII. 



With the same arrangement as in the last experiment, and with the same initial 

 arc of vibration, the following was found to be the effect of sustained longitudinal 

 magnetisation on the vibration-period, the battery power used being the same as 

 before. 



* The subsidence for 52 vibrations when the solenoid is excited is 608, and when the solenoid is not 

 excited 500, the former being 21 per cent, greater than the other. Again, the subsidence in 20 

 vibrations is 3C per cent, greater when the solenoid is excited than when it is not excited. 



