40 UNDULATION GRAVITATION.MTfTOTOH'l 



or ray, the several distinct and separate molecules, or atoms of 

 light, which were (for the moment previous) standing isolated 

 in every space, or distance, of 192,000 miles which intervenes 

 between the luminous body and the observer; and it may be 

 further added, that the emanation, whether from the sun's disc 

 or atmosphere, or from the reflection of light from other of the 

 heavenly bodies, appears to afford the same effect, that is, the 

 commencement of a pressure sufficient to place the atoms, or 

 molecules of Iight 9 within the necessary distance or space of 

 mutual attraction for the completion of the line, and its conti- 

 nuance, as long as the luminous object is visible, or the line 

 uninterrupted by the interposition of an opaque body. 



The theory of the existence of an ethereal substance pervad- 

 ing space, penetrating all material bodies, and occupying the 

 interstices between their molecules, I consider perfectly sus- 

 tained, and that light, or its constituents, in their molecular 

 state, is that ethereal substance. That it exists in a position of 

 isolated independence as to its atoms, and that it is subject to 

 the following varieties of action, according to the necessity that 

 may occur for its agency in the progress of nature, or the 

 works of art. 



First, That by the absorption by fixed matter, of one or more 

 of its original constituents, it is decomposed. Secondly, That 

 it is separable by the exertion of galvano-eleetrical influence 

 one constituent passing to one pole, and the two other constitu- 

 ents proceeding to the other pole ; and that the same operation 

 is performed by Nature, in the shape of silent electrical dis- 

 charges, keeping up those constant currents of electricity essen- 

 tial to her works always in active progress. 



Thirdly, That in the necessity to supply the deficiency which 

 may have occurred on one side or the other, either of the mag- 

 netic powers, when minus, or plus, in quantity, the needful 

 portion of the acquired constituent is immediately afforded, to 

 keep up or restore equilibrium, so that the power of effectual 

 GRAVITATION is never for one MOMENT SUSPENDED. 



