OF NATURAL PHILOSOPHY. 333 



mulated, its repulsion for its own kind and attraction 

 of the opposite species in neighbouring bodies tends 

 to disturb the natural equilibrium of the two fluids 

 present in them, and to produce phenomena of a 

 peculiar description, which are termed induced elec- 

 tricity. Curious and artificial as this theory may 

 appear, there has hitherto been produced no phe- 

 nomenon of which it will not afford at least a plau- 

 sible, and in by far the majority of cases a very 

 satisfactory, explanation. It has one character 

 which is extremely valuable in any theory, that of 

 admitting the application of strict mathematical 

 reasoning to the conclusions we would draw from 

 it. Without this, indeed, it is scarcely possible 

 that any theory should ever be fairly brought to 

 the test by a comparison with facts. Accordingly, 

 the mathematical theory of electrical equilibrium, 

 and the laws of the distribution of the electric 

 fluids over the surfaces of bodies in which they 

 are accumulated, have been made the subject of 

 elaborate geometrical investigation by the most 

 expert mathematicians, and have attained a degree 

 of extent and elegance which places this branch of 

 science in a very high rank in the scale of ma- 

 thematico-physical enquiry. These researches are 

 grounded on the assumption of a law of attraction 

 and repulsion similar to those of gravity and mag- 

 netism, and which by the general accordance of 

 the results with facts, as well as by experiments 

 instituted for the express purpose of ascertaining 

 the laws in question, are regarded as sufficiently 

 demonstrated. 



(371.) The most obscure part of the subject is no 



