438 OHM ON THE GALVANIC CIRCUIT. 



stitute for this part; then its electroscopic force, measured in 

 the way described, will, when it happens to be different at the 

 various places, make known the relative difference with regard 

 to electricity between these places. 



The intention of the preceding explanations is to give a sim- 

 ple and determinate signification to the expression "electro- 

 scopic force "; it does not come within the limits of our plan to 

 take notice either of the greater or less practicability of this 

 process, nor to compare inter se the various possible modes of 

 proceeding for the determination of the electroscopic force. 



2. We perceive that the electroscopic force moves from one 

 place to another, and from one body to another, so that it does 

 not merely vary at different places at the same time, but also at 

 a single place at different times. In order to determine in what 

 manner the electroscopic force is dependent upon the time 

 when it is perceived, and on the place where it is elicited, we 

 must set out from the fundamental laws to which the exchange 

 of electroscopic force occurring between the elements of a body 

 is subject. 



These fundamental laws are of two kinds, either borrowed 

 from experiment, or, where this is wanting, assumed hypothe- 

 tically. The admissibility of the former is beyond all doubt, and 

 the justness of the latter is distinctly evident from the coinci- 

 dence of the results deduced from calculation with those which 

 actually occur ; for since the phaenomenon with all its modifica- 

 tions is expressed in the most determinate manner by calculation, 

 it follows, since no new uncertainties arise and increase the earlier 

 ones during the process, that an equally perfect observation of 

 nature must in a decisive manner either confirm or refute its 

 statements. This in fact is the chief merit of mathematical 

 analysis, that it calls forth, by its never- vacillating expressions, 

 a generality of ideas, which continually excites to renewed ex- 

 periments, and thus leads to a more profound knowledge of 

 nature. Every theory of a class of natural phaenomena founded 

 upon facts, ^/hich will not admit of analytical investigation in 

 the form of its exposition, is imperfect ; and no reliance is to be 

 placed upon a theory developed in ever so strict a form, whicli 

 is not confirmed to a sufficient extent by observation. So lonj 

 therefore as not even one portion of tiie effects of a natural forc( 

 has been observed with the greatest accuracy in all its grada 

 tions, the calculation employed in its investigation only tread; 



7 



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