561 



IV. 



THE RING OF THE ZODIACAL LIGHT. 



In our solar system, so rich in varieties of form, the ex- 

 istence, place, and configuration of many individual members 

 have been discovered, since scarcely a century and a half, and 

 at long intervals of time: first, the subordinate, or particular 

 systems, in which, analogous to the principal system of the 

 Sun, smaller spherical cosmical bodies revolve round a larger; 

 then concentric rings round one, and that indeed one of the 

 less dense and exterior planets which possesses the greatest 

 number of satellites ; then the existence, and probably ma- 

 terial cause, of the mild, pyramidal-formed, zodiacal light, 

 very visible to the naked eye ; then the mutually intersecting 

 orbits of the so-called small planets, or asteroids, inclosed 

 between the regions of two principal planets, and situated 

 beyond the zodiacal zone ; finally, the remarkable group of 

 interior comets, whose aphelia are smaller than those of 

 Saturn, Uranus, and Neptune. In a cosmical representation 

 of universal space, it is necessary to call to mind the difference 

 of the members of the solar system, which by no means 

 excludes similarity of origin and lasting dependence upon the 

 moving forces. 



Great as is the obscurity which still envelops the material 

 cause of the zodiacal light, still, however, with the mathe- 

 matical certainty that the solar atmosphere can not reach 

 beyond $ of the distance of Mercury, the opinion supported 

 by Laplace, Schubert, Arago, Poisson, and Biot, according to 



