184 



RESEARCH 



or capacity, had met with general approval. The 

 principal object of the committee was, first, to de- 

 termine what would be the most convenient unit 

 of resistance, and, second, what would be the best 

 form and material for the standard representing that 

 unit.' ! 



The committee, which during 1862-70 included, 

 in addition to Thomson, Williamson, Wheatstone, Sir 

 Charles Bright, Clerk Maxwell, C. W. Siemens, 

 Balfour Stewart, and others, did much valuable 

 work, and its earlier reports are a mine of useful 

 information. 



The idea of a consistent absolute system of units 

 is due to W. Weber. An absolute system is one 

 in which all the units can be directly expressed 

 in terms of some fundamental mechanical units 

 arbitrarily chosen in such a manner as to produce 

 a consistent system in which every number is 

 connected by some known physical law with every 

 other. The fundamental mechanical units univer- 

 sally adopted are those of length, mass, and time, 

 and for these the committee, after much discussion 

 and correspondence, selected the centimetre, the 

 gramme, and the second. Hence arose the C.G.S. 

 system of measurement which has contributed 

 probably more than any other single event to the 

 rapid progress of electricity. For the committee 

 then proceeded to show how the various quantities 

 which occur in electrical measurements were con- 

 nected with these primary units, and Appendix C 

 to their second report (Newcastle, 1863) is a 



1 Introduction to collected Reports of the Committee on Electrical 

 Standards, by Sir B. T. Glaze brook and F. E. Smith (Cambridge, 

 1913). 



