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XCVI. Simple Model to illustrate Elastic Hysteresis. 



To the Editors of the Philosophical Magazine. 

 Gentlemen, — 



REGARDING the very interesting paper by Mr. S. Lees, 

 M.A., St. John's College, Cambridge, " On a Simple 

 Model to illustrate Elastic Hysteresis " in your current 

 issue for September, 1922, may I be permitted to refer to 

 an earlier publication by your present correspondent in the 

 pages of the 'Physical Review' (Ithaca, N.Y., U.S.A.) for 

 June last. 



Before the Physical Society there had been described the 

 model illustrated below, which involved both spring and 



solid frictional constraints, similar to those employed by 

 Mr. Lees. 



The model enabled the writer to explain not only mechani- 

 cal hysteresis, but electrical and magnetic hysteretic systems, 



