2 Mr Griffiths and Mr Clark, Note on the [Oct. 31, 



The retiring President, Prof. G. H. Darwin, addressed the 

 Society upon the History of the Society during his tenure of 

 office. 



Sir Kobert Stawell Ball, Lowndean Professor of Astronomy 

 and Geometry, and Mr R. A. Sampson, M.A., St John's College, 

 were elected Fellows of the Society. 



The following communications were made to the Society : 



(1) Note on the Determination of Low Temperatures hy 

 Platinum-Thermometers. By E. H. Gkiffiths, M.A, Assistant 

 Lecturer at Sidney College, and G. M. Clark, B.A., Sidney 

 College, 



In connexion with Profs. Dewar and Fleming's recent work 

 on the resistance of certain metals and alloys at very low tem- 

 peratures, and the suggestion that they have made — viz. that 

 the resistance of certain pure metals (amongst which is plati- 

 num) vanishes at absolute zero, — the following facts may be of 

 interest. 



Having previously published the constants of several platinum- 

 thermometers, whose accuracy has been exposed to severe tests, 

 we have, by assuming the possibility of applying Callendar and 

 Griffiths' method, calculated the temperature at which R = 

 from the formulae 



and 



where R^, Ro are the resistances in steam under normal pressure, 

 and melting ice, respectively, and R is the resistance at tem- 

 perature t ; the value of S for each thermometer having been 

 determined by observations of the resistance in boiling sulphur 



(t = 444°-53). 



The following table gives the constants and results : — 



The actual numbers used in these calculations are those taken 

 from the papers referred to in column 2. 



All the other thermometers mentioned by Griffiths (Phil. 

 Trans. A. 1891, pp. 43 — 72) were made with single electrodes 

 for rapid observations ; and thus every observation includes their 

 stem- resistance, which evidently cannot become zero, so that the 

 above investigation with their constants would be of no use. 



