58 



Prof. J. A. Ewing. 



[Jan. 8, 



January 8, 1885. 



THE TREASURER in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



Dr. Morrison Watson was admitted into the Society. 



In accordance with the announcement made from the Chair at the 

 last Meeting,the question of Mr. James Bateman's re-admission was 

 put to the vote. It was decided in the affirmative, whereupon the 

 Treasurer declared that Mr. Bateman was re-admitted into the 

 Society. 



The following Papers were read : — 



I. " Experimental Researches in Magnetism." By Professor 

 J. A. Ewing, B.Sc, F.R.S.E., University College, Dundee. 

 Communicated by Sir William Thomson, F.R.S. Received 

 December 5, 1884. 



(Abstract.) 



The paper describes in detail experiments of which preliminary 

 notices have already been published in the " Proceedings of the Royal 

 Society," vol. 34, p. 39, and in the " Philosophical Magazine," 

 November, 1883. The experiments relate to — 



(1.) The magnetic susceptibility of iron and steel, the form of the 

 magnetisation curve, and the changes of magnetism caused by cyclic 

 changes of magnetising force. 



(2.) The influence of vibration on magnetic susceptibility and reten- 

 tiveness. 



(3.) The influence of permanent strain on magnetic susceptibility 

 and retentiveness. 



Order," Arts. 53-58, it is shown that the general form of which the criticoid J 2 i s 

 a particular case, enables us to solve for all orders the problem of destroying the 

 second and third terms, that is, it makes it depend on the solution of equations of 

 the orders 1 and 2. For other applications of the theory, see Cockle " On Primary 

 Forms," Arts. 6-14, " Philosophical Magazine " for February, 1875, vol. xlix, ser. 

 4, pp. 134-142. See also the " Mathematical Eeprint from the Educational Times," 

 vol. 34, pp. 109, 110 ; Question 6503. 



