96 DYNAMIC AGENTS. 



By subsequent electro-magnetic experiments with an arti- 

 ficial globe called the terrelle, Reichenbach succeeded in pre- 

 cisely reproducing the appearances of the aurora borealis, and 

 may be considered as having probably afforded a complete 

 solution of that interesting phenomenon. 



We find in these remarkable facts a complete verification of 

 our previous hypothesis, so far as it relates to an essence 

 which may be called secondary light. While this light is, in 

 some particulars, similar to ordinary light, it differs from it 

 totally in others, as the foregoing description renders obvious ; 

 and it therefore may be judged to belong to a somewhat differ- 

 ent degree of natural developments. Considering this, there- 

 fore, as one of the members of our supposed Secondary Trinity 

 of imponderables, we shall now see that our hypothesis, so far 

 as it relates to the other two members, is not without the sup- 

 port of similar facts. 



When a horseshoe magnet was closed by an armature, all 

 appearances of a luminous flame would immediately cease, 

 but would be instantly reproduced on the removal of the 

 armature. This establishes the probability that the same force 

 which in the open magnet generates the luminosity, is, by the 

 application of the armature, simply rendered latent, so far as its 

 flame-generating power is concerned, but that it nevertheless 

 still exists in the closed magnet, and acts as an internal prin- 

 ciple, or as a principle corresponding to fire or heat. This 

 view is further confirmed by the fact that one of Rsichenbach's 

 subjects saw even closed magnets, and, indeed, metals of all 

 kinds, luminous in the dark, as though they had been heated 

 to incandesence without, however, giving forth any flame-like 

 scintillations. Such, then, are the evidences of a Secondary 

 Heat. 



But still more conclusive indications were obtained of an 



