304 WRITINGS OF JOSEPH HENRY. [1851 



when the iron is de-magnetized, (if the expression ma}^ be 

 allowed,) a similar change in the position of the molecules 

 is indicated. 



In the explanation of the statical phenomena of electricity 

 we may either adopt the hypothesis of one or of two fluids, 

 the mechanical results which are logically deduced from 

 either being the same; in the case of the former we have one 

 movable and one fixed principle; in that of the latter we 

 have two movable fluids and a fixed medium. It is evident 

 that the mechanical results will be the same in the two 

 theories, provided we suppose the absolute motion of the one 

 fluid to be equivalent to the sum of the motions of the two 

 fluids. Though either theory may be adopted with reference 

 to the statical phenomena, the theory of one fluid is more 

 readily applicable to the facts connected with electricity in 

 motion, and particularly that part of the theory which 

 assumes the activity of ordinary matter may hereafter be 

 fruitful in new deductions. 



The discoveries of the last few years have tended more 

 and more to show the intimate connection of all the phe- 

 nomena of the " imponderables ;" and indeed we cannot avoid 

 the conclusion, forced upon us by legitimate analogy, that 

 they all result from the diff"erent actions of one all-pervad- 

 ing principle. Take, for illustration, the following example 

 of the development of the several classes of phenomena. An 

 iron rod rapidly hammered becomes red hot, or in other 

 words, emits heat and light. The same rod insulated by a 

 non-conductor and struck with another non-conductor ex- 

 hibits electrical attraction and repulsion. Again, if this rod 

 be struck with a hammer while in a vertical position it be- 

 comes magnetic. We have here the evolution of the four 

 classes of phenomena by a simple agitation of the atoms. 

 We cannot, in accordance with the known simplicity of the 

 operations of nature, for a moment imagine that these dif- 

 ferent results are to be referred to as many different and 

 independent principles. 



If we refer all these phenomena to one elastic medium it 

 will be necessary, in order to explain the facts of electricity 



