ON THE SPECIFIC IIKS1SI \.NVl-; Of MKUrrUY. 



373 



TAI-.I.I: X. 



STBKCKIR* 



SlIMKNSf 

 LoKENZj 



LENZ 

 BBNOIT || 



GLAZIBBOOK** ...... 



GLAZEBKOOK and FITZPATBICK ft 



Mean 



Avenge coefficient up to 10. 



000909 

 000865 

 000901 

 000884 

 000877 

 000861 

 000861 

 000876 



000879 



Thus, STRECKER'S value is higher than the mean by '00003, and if we were to 

 reduce his observations from 10 to 0, using the mean coefficient given above, we 

 should obtain the value for r, '95362. 



This value may possibly be a little too high, but at any rate the reasoning is suffi- 

 cient to show that the difference may easily depend on a small error in the tempera- 

 ture coefficient. 



The same reasoning will apply to KOHLRAUSCH'S results, for his comparisons 

 between the mercury tubes and the wire standards were usually made at temperatures 

 differing from 0, and were reduced to by the use of STRECKER'S formula. 



The value of the ohm in centimetres of mercury at 0, as given by KOHLRAUSCH in 

 a letter to R. T. G., February 16, 1888, is 106'32, agreeing exactly with ROWLAND. 



MASCART, NERVILLE, and BENOIT found a value for r which is as much above our 

 value as KOHLRAUSCH is below it. At the same time, their value of the B.A. unit in 

 ohms is less than ours, leading to the result that the value of the ohm in centimetres 

 of mercury is 106 '33 ; or, again, the same value as ROWLAND'S. This might seem to 

 show that there was some small change in the B.A. unit used by MASCART between 

 the time it was compared at Cambridge and the date of their observations. 



[Quite recently, June 4, 1888, M. WUILLEUMIER communicated to the Academy of 

 Sciences at Paris the results of some experiments by LIPPMANN'S method, which give 

 the value 106 '27.] 



Thus we may conclude that the experiments of MASCART, STRECKER, ROWLAND, 

 KOHLRAUSCH, WUILLEUMIER, and ourselves are in fairly close agreement, and that 



* ' WIKDEIIANN, Annalen,' vol. 25, p. 475. 



t ' Electrotechn. Zeitschr.,' vol. 3, 1882, p. 408. 



J ' WIEDEMANN, Annalen,' vol. 25, p. 11. 



' Etudes Electrometrologiques,' vol. 2, 1884. 



|| " Resume d'cxperiencea sur la determination de 1'ohra," 'Journal de Physique,' 1884, p. 230. 



f ' Phil. Trans.,' 1883, p. 185. 



* ' Phil. Mag.,' October, 1885, p. 352. 



ft Supra, p. 372. 



