ABSTRACTS OF TECHNICAL ARTICLES 363 



BozoRTH and H. Christensen. This paper describes measurements of the 

 changes in certain physical properties of 68 Permalloy that result from dif- 

 ferent thermal and mechanical treatments and considers them in relation 

 to the domain theory. The magnetostriction varied with heat treatment 

 from 2.5 X 10~^ to 22 X 10~^. The change in Young's modulus with 

 magnetization to saturation varied from 0.09 to 10.5 per cent. The damp- 

 ing of mechanical vibrations was also measured as dependent on magnetiza- 

 tion and heat treatment. Young's modulus and the damping constant 

 were determined by measuring the natural frequency of vibration and the 

 width of the resonance curve of a hollow rectangle magnetized parallel to 

 its sides so that the magnetic circuit was complete without air gaps or end 

 effects. 



