98 SCIENCE IN SHORT CHAPTERS. 



my case this view of the solar constitution of tie larger 

 planets is not a matter of mere opinion, or guessing, or piob- 

 ability, but it follows of necessity, and as stated on page 200, 

 " the great mystery of Saturn's rings is resolved into a simple 

 consequence, a demonstrable and necessary result of the opera- 

 tion of the familiar forces, whose laws of action have been 

 demonstrated here upon the earth by experimental investiga- 

 tion in our laboratories. No strained hypotheses of imaginary 

 forces are required, no ethers or other materials are demand- 

 ed, beyond those which are beneath our feet and around our 

 heads here upon our own planet ; all that is necessary is to 

 grant that the well-known elements and compounds of the 

 chemist, and the demonstrated forces of the experimental 

 physicist, exist and operate in the places, and have the quanti- 

 ties and modes of distribution described by the astronomer ; 

 this simple postulate admitted, these wondrous appendages 

 spring into rational existence, and like the eternal fires of the 

 sun, the barren surface of the moon, the dry valleys of Mer- 

 cury, the hazy equivocations of Venus, the seas and continents 

 and polar glaciers of Mars, and the cloud- covered face of 

 Jupiter, follow as necessary consequences of a universal atmos- 

 phere." 



If I am right in ascribing a gaseous condition to the sun and 

 the larger planets, and tracing the maintenance of this condition 

 to the disturbing gravitation of the attendant planets or satellites, 

 a solution of the riddle of the nebula; at once presents itself. 

 We have only to suppose a star-cluster or group composed of 

 orbs of solar or great planetary dimensions, and that these act 

 mutually upon each other as the planets on our sun, or the satel- 

 lites upon Saturn, but in a far more violent degree owing to 

 the far greater relative masses of the reacting elements, and we 

 obtain the conditions under which great gaseous orbs would 

 be not merely pitted on their surface, but riven to their very 

 centres, moulded and shaped throughout by the whirling hurri- 

 cane of their whole substance. When thus in the centre of a 

 tornado of opposing gravitations the tortured orb would be 

 twisted bodily into a huge vorticose crater, into the bowels of 

 which the aqueous vapor would be dragged and dissociated, 

 and then, entangled with the inner matter of the riven sphere, 

 would be hurled upward, again to burst forth in an explosion 

 of such magnitude that the original body would be measurably 

 presented as a mere appendage, the rocket case of the flood of 

 lire it had vomited forth. 



