Principles of the Nebular Theory. 



267 



or three days shorter time than the polar regions. Those polar 

 regions, being near the axis of rotation, must always have 

 sympathized more with the unrotating interior, because they 

 had less distance to fall to the axis to acquire velocity by their 

 falls. The present excess of equatorial velocity must be 

 regarded as a relic of the past, just as fossil remains in the 

 earth's crust tell of the state of things in times long ago. 



It follows from these principles that the atmosphere of the 

 sun should rotate more rapidly than even its liquid equatorial 

 zone ; and this has just been discovered to be true by Young. 

 The solar atmosphere must have an inconceivably great mo- 

 mentum ; and it cannot easily be stopped by friction on the 

 flaming liquid interior. According to Harkness, " one cubic 

 mile of our atmospheric air weighs 5,621,000 tons." If the 

 solar atmosphere holds the same proportion in mass that ours 

 does to the earth, then its height, according to Trowbridge, 

 must be 606,000 miles. We know of no reason why the pro- 

 cess of contraction in the sun should have ceased. And this 

 contraction must add velocity to the solar atmosphere, and 

 daily aid it to overcome friction, and to keep its speed in ad- 

 vance of the underlying liquid body of the sun. 



Having shown how rotation must begin in the vast primi- 

 tive nebulae which formed sidereal systems, I now proceed to 

 point out how rotation must begin in the nebulae which resulted 

 from broken rings, and condensed into individual suns and 

 planets and satellites. 



Let C (fig. 4) be the centre of a 

 nebula, and A B D an abandoned ring, 

 or fragment of a ring, moving with 

 the arrow. The exterior (e) of the ring, 

 or of the globe in which it has con- 

 densed, possesses a greater linear ve- 

 locity than its interior at n. There- 

 fore, in contracting, the exterior at e 

 will have a greater velocity than the 

 centre, and will fall before it, and the 

 interior at n will have a lesser velocity 

 than the centre and will fall behind it. 

 From these two facts, as seen by the 

 arrows moving from e and n, the be- 

 ginning of a rotation is plainly a 

 necessity. In the sun we now behold the most unquiet and 

 agitated of all known places, caused, as I have tried to prove, 

 by chemical action. This agitation must have raged with 

 extreme violence in the nebulae, and must have caused various 

 irregularities in the sizes and densities of the planets, in their 

 distances apart, and inclinations of their axes. 



Fig. 4. 



