THE ORIGIN OF WORLDS. 5 



that the electro-magnetic power would be favored with a good conductor 

 for extending its control to great distances, and its effects can be traced 

 without having recourse to any unwarranted assumptions respecting the 

 passage of electricity through an absolute vacuum or through interstel- 

 lar space. 



The operation of such an agency in the heavens is shown by re- 

 searches of a different character. M. Gaston Plante, of Paris, has been 

 led by experimental evidence alone to ascribe the form of the spiral 

 nebulae to electro-magnetic action ; as their peculiar features correspond 

 exactly to that which he produced by powerful electric currents under 

 the controlling influence of a magnet. But the influence of the same 

 forces is strongly impressed on the form of another class of nebulous 

 objects. By investigations similar to those of Laplace in regard to the 

 possible extent of the solar atmosphere, it may be proved that a rare 

 gas surrounding a dense nucleus and with a uniform rotation could not 

 be compressed in a greater degree than to show a thickness two thirds 

 of its equatorial dimensions. Yet in many nebula? with a central con- 

 densation the greater diameter is more than four times the less, and this 

 would seem to indicate the operation of some force like dynamic elec- 

 tricity acting along the plane of the equator of these rarefied objects. 

 The evidence on this point will seem stronger when we recollect that 

 observation gives only an inadequate picture of the effects of this cause ; 

 as, in consequence of the position in which they are viewed, planetary 

 nebula? scarcely ever exhibit the full amount of their ellipticity or com- 

 pression. 



Other facts assist in revealing the nature of the forces at work in 

 these celestial curiosities. Judging from peculiarities they present in 

 the spectroscope, Lockyer and Frankland have concluded that several 

 of the nebula? must possess an exceedingly low temperature. Yet it is 

 difficult to conceive that such cold, rarefied masses could be self-luminous, 

 or that they could be visible to us even when surrounding a central sun, 

 for gases have but a very feeble power of reflecting light. The diffi- 

 culty, however, may be removed by supposing that the visibility of 

 these nebula? depends on the passage through them of electricity devel- 

 oped in some dark or bright binary system on the incorporation of the 

 lesser with the greater orb. In this way an explanation may be found 

 for the mysterious and unaccountable variations in the brightness of 

 these objects. From the careful observations of Hind, D' Arrest, and 

 other astronomers, it has been shown that, in a few cases, nebula? have 

 declined in light so as to become invisible, but reappeared after a time ; 

 thus exhibiting changes equally fatal to the ideas that they are congre- 

 gations of stars or collections of fire-mist gradually cooling and condens- 

 ing into planetary systems. But the mystery will be removed when we 

 regard their light as dependent on the electro-magnetic action already 

 described ; for in its latter stages, especially when the tides on the 

 smaller member of the binary were drawing to a close, there would be 



