228 M. W. Weber on the Measurement of Electric 



closer consideration shows that even of these three fundamental 

 measures, the measure of mass does not come into consideration, 

 as follows from the following summary of the simple relations 

 which are established by the determination of the absolute mea- 

 sures of these various kinds of magnitude. 



As fundamental measures, there are to be considered the mea- 

 sure of length R, and the measure of time S ; as absolute measures, 

 the superficial measure F, and the units of measure of bar mag- 

 netism M, of terrestrial magnetism T, of electromotive force E, of 

 intensity I, and of resistance W. 



Hence, first, if wW is the resistance of any closed circuit, 



eE the electromotive force acting upon this conductor, and il the 



intensity of the current produced by this electromotive force, we 



have the relation between the three numbers 



e 

 w— -.; 

 i 



from which it is clear that if the numbers e and i are determined, 

 the number w is also indirectly obtained without needing a special 

 determination. 



Secondly, let <?E stand for the electromotive force which acts 

 upon any closed (plane) conductor, f¥ the area of the plane en- 

 closed by this conductor, ^T the earth's magnetism on which the 

 electromotive force depends ; and let sS express the space of 

 time in which the plane of that conductor is moved by rotation 

 from a position parallel to the direction of the earth's magnetism 

 to a position at right angles to it, in such a manner that the 

 limited surface produced by its projection on a plane at right 

 angles to this direction of the earth's magnetism increases by 

 the unit of measure during the unit of time proportional to the 

 time. We shall then have between these four numbers e, f t, s, 

 the following relations, 



S 



and hence it is clear that if the three numbers /, /, s are deter- 

 mined, the number e is also thereby directly given without 

 necessitating a special measurement. 



If, thirdly, il is the intensity of the current in any closed con- 

 ductor, /F the area of the plane enclosed by this conductor, and 

 mlM the magnetism of a bar which, when substituted for that 

 conductor (its magnetic axis at right angles to the plane of the 

 conductor), exercises the same actions at a distance, according to 

 electro-magnetic laws, as that conductor, the following relation 

 obtains between the three numbers i,f and in, 



m 



