95 



CHAPTER VI. 

 THEORY OF ELECTRODYNAMICAL ACTION. 



AMPERE'S Theory. Nothing can show in a 

 ^jL more striking manner the advanced condi- 

 tion of physical speculation in 1820, than the re- 

 duction of the strange and complex phenomena of 

 electromagnetism to a simple and general theory as 

 soon as they were published. Instead of a gradual 

 establishment of laws of phenomena and theories 

 more and more perfect, occupying ages, as in the 

 case of astronomy, or generations, as in the instances 

 of magnetism and electricity, a few months sufficed 

 for the whole process of generalization; and the 

 experiments made at Copenhagen were announced 

 at Paris and London, almost at the same time with 

 the skilful analysis and comprehensive inductions 

 of Ampere. 



Yet we should err if we should suppose, from 

 the celerity with which the task was executed, that 

 it was an easy one. There were required, in the 

 author of such a theory, not only those clear con- 

 ceptions of the relations of space and force, which 

 are the first conditions of all sound theory, and a 

 full possession of the experiments ; but also a mas- 

 terly command of the mathematical arms by which 

 alone the victory could be gained, and a sagacious 

 selection of proper experiments which might decide 

 the fate of the proposed hypothesis. 



It is true, that the nature of the requisite hypo- 



