On a Compensated Air Thermometer. 247 



December 10, 1891. 

 Sir WILLIAM THOMSON, D.C.L., LL.D., President, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The President announced that he liad appointed as Vice-Presi- 

 dents 



The Treasurer. 

 Professor G. C. Foster. 

 Professor Liveing. 

 Sir G. G. Stokes. 



The President read the following Letter from Professor Dewar : 



Eoyal Institution, 



10th December, 1891. 

 DEAR SIR WILLIAM THOMSON, 



The following observation, which I have just made, may interest 

 the members of the Royal Society, and if you think it of sufficient 

 importance you may announce it at this day's meeting. 



At 3 P.M. this afternoon I placed a quantity of liquid oxygen in the 

 state of rapid ebullition in air (and therefore at a temperature of 

 181 C.) between the poles of the historic Faraday magnet, in a 

 cup-shaped piece of rock salt (which I have found is not moistened 

 by liquid oxygen, and therefore keeps it in the spheroidal state), and 

 to my surprise I have witnessed the liquid oxygen, as soon as the 

 magnet was stimulated, suddenly leap up to the poles and remain there 

 permanently attached until it evaporated. To see liquid oxygen 

 suddenly attracted by the magnet is a very beautiful confirmation of 

 our knowledge of the properties of gaseous oxygen. 



Yours faithfully, 



JAMES DEWAR. 

 The following Papers were read : 



I. <: On a Compensated Air Thermometer." By H. L. CALLENDAR, 

 M.A., Fellow of Trinity College, Cambridge. Communi- 

 cated by Professor J. J. THOMSON, F.R.S. Received 

 October 29, 1891. 



In a paper which I had the honour to present to the Royal Society 

 some four years ago " On the Practical Measurement of Tempera- 

 VOL. L, s 



