372 



MESSRS. R. T. GLAZEBROOK AND T. C. F1TZPATRICK 



TABLE IX. 



We conclude finally from the experiments that the value of 



r is '95352 B.A. unit. 



If we take as the value of the B.A. unit the mean of those found at the Cavendish 

 Laboratory, we have 



1 B.A. unit = -98667 Ohm, 

 we find that 



r = 94081 Ohm, 



or 1 ohm is equal to resistance at C. of a column of mercury 1 square millimetre in 

 area and 



106*29 centimetres in length. 



These values agree closely with those communicated at Manchester to the British 

 Association by Professor ROWLAND, viz. : 



r = -95349 B.A. unit. 

 1 ohm = 106 '32 centimetres of mercury at C. 



The value of r in B.A. units does not differ greatly from that found at Wurzburg by 

 STRECKER and by KOHLRAUSCH ;* the difference, however, is greater than can be 

 accounted for by error of experiment, but is, I think, capable of easy explanation. 



STRECKER'S comparison of his mercury tubes with one of the B. A. units sent from 

 Cambridge was made at a temperature of from 9 C to 10"5 (' WIEDEMANN, Annalen,' 

 vol. 25, p. 482). The resistance of the mercury at this temperature was reduced to 

 by means of his own formula (loc. cit., p. 474), which gives a mean coefficient up to 

 10 of '000909. Now, this is a larger value than is given by any other observer, as is 

 shown in the following Table : 



* See the Table on page 352. 



