ELECTRICAL UNITS OF MEASUREMENT. 83 



Maasbestimmungen?- and thence into electro- 

 statics in his joint work with Kohlrausch, under 

 tho same title, Elektrodynamische Maasbestim- 

 mungen? The now celebrated " v " (velocity), 

 which Maxwell in his electro-magnetic theory 

 of light pointed out to be not merely by chance 

 approximately equal to the velocity of light, but 

 to be probably connected physically, in virtue of 

 the forces concerned, with the actual action or 

 motion of matter which constitutes light, was 

 found to be approximately 300,000 kilometres 

 per second. 3 



As early as 1851 I commenced using the 

 absolute system in the reckoning of electromotive 

 forces of voltaic cells, and the electric resistances 



1 Leipsip, 1852. An earlier publication of one of the most 

 important parts of the work was Weber's paper, "Messungen 

 galvanischen Leitungswidentande nach einen absoluten Maasse." 

 Poggendorffs Annalen, March 1851. 



2 Poggendorffs Annaleti, August 10, 1856. 



:i The exact number given by Weber and Kohlrausch is 310,740 ; 

 but more recent investigations render it probable that this number 

 may be 3 or 4 per cent, too great. See also Gray's Absolute 

 Measurements in Electricity and Magnetism (Macmillan and Co., 

 London, 1883). 



G 2 



