2 Mr Searle, A method of measuring the [Nov. 11, 



The following resolutions were proposed by Prof. Liveing, 

 seconded by Prof. Hughes, and carried unanimously. 



" That this meeting desires to place on record its sense of the 

 loss the Society has sustained by the death of Prof. Babington 

 and to convey to Mrs Babington the expression of their sympathy 

 and condolence in her bereavement." 



" That the President be requested to convey to Mrs Babington 

 the foregoing resolution." 



The following resolutions were proposed by Prof. N ewton, 

 seconded by Prof. G. H. Darwin, and carried unanimously. 



"That the Fellows of the Cambridge Philosophical Society at this 

 their first meeting since the death of the Rt. Hon. Thomas Henry 

 Huxley, LL.D., desire to express their sympathy with Mrs Huxley, 

 and to record their sense of the depth of his influence on modern 

 thought and on the progress of Biological Science." 



" That the President be requested to convey to Mrs Huxley the 

 foregoing resolution." 



Monday, 11 November 1895. 

 Professor J. J. Thomson, President, in the Chair. 



The following Communications were made to the Society : 



(1) A method of measuring the loss of energy in Hysteresis. 

 By G. F. C. Searle, M.A., Peterhouse. 



The extensive employment of transformers in the distribution 

 of energy by alternating electric currents has caused the measure- 

 ment of hysteresis in iron to become a matter of such commercial 

 importance as to stimulate efforts to find a means for readily 

 testing iron as to its quality with respect to hysteresis. The 

 subject is important not only commercially but also from the 

 purely scientific point of view, for it can hardly be doubted that 

 our knowledge of the molecular structure of iron would receive 

 some extension if a means were provided by which the effects of 

 various physical conditions — stress, temperature, the passage of 

 electric currents &c. — upon the loss of energy in hysteresis could 

 be investigated with a comparatively small expenditure of time. 



As is well known, the loss of energy occasioned by any cyclic 

 change in the magnetization of iron is equal to jHdl in ergs 

 per cubic cm. of iron per complete cycle, H denoting the magnetic 

 force and / the intensity of magnetization, both in C.G.S. units. 

 The waste of energy, JHdl, I shall denote by W. The value of 

 JHdl may be obtained by plotting in a curve the simultaneous 

 values of H and / from a numerous series of observations, and 



