30 ELEMENTS OF STATIC ELECTRICITY. 



Recent experiments have- demonstrated that unusual 

 disturbances in the variation of the magnetic needle 

 are coincident with unusual disturbances in the sun, in 

 connection with the phenomena known as sun spots ; 

 and that the telegraph and telephone are, at such 

 times, seriously disturbed by what are known, techni- 

 cally, as "electric storms"; that is, unusual disturb- 

 ances in the earth's electricity shown in the phenomena 

 known as earth currents. 



It has also been found that these solar disturbances 

 are periodic; and that these periods, for the last hundred 

 and fifty years, correspond almost exactly with the 

 periods of unusual variation of the magnetic needle. 



Since the sun is our chief source of light and heat, 

 since they are, in fact, the result of the constant dis- 

 turbance of the elements of that body; and since, when 

 this disturbance assumes an unusual phase, there is, co- 

 incident with it, an unusual disturbance in the earth's 

 electricity, it must be accepted as strong proof of a 

 common origin of heat, light, and electricity. 



We have heat, light, and electricity derived from 

 friction, from chemical action, from magnetic action, 

 and from the sun. We have heat producing electric- 

 ity, and electricity producing heat and light ; and we 

 have electricity neutralizing the polarizing effect of 

 light. The evidence of identity then becomes cumu- 

 lative, while that of close alliance amounts to demon- 

 stration. Hence we may infer certain facts in regard 

 to the nature of electricity from what we know of 

 similar facts in regard to the nature of light and heat. 

 And we are also warranted in the conclusion, that a 

 well supported theory of light or heat requires but 

 little modification to adapt it to electricity. 



