PROBABLE CONSTITUTION OF THE SUN. 285 



which our terrestrial experiences afford no adequate war 

 rant ; and if such unlikeness exists, it is very improbable 

 that it should produce so immense a contrast in -specific 

 gravity as that of 4 to 1. The more legitimate conclusion 

 is that the Sun's body is not made up of molten matter all 

 through ; but that it consists of a molten shell with a 

 gaseous nucleus. And this we have seen to be a corollary 

 from the Nebular Hypothesis. 



Considered in their ensemble^ the several groups of evi- 

 dences assigned amount almost to proof. We have seen 

 that, when critically examined, the speculations of late 

 years current resj^ecting the nature of the nebula3, commit 

 their promulgators to sundry absurdities ; while, on the 

 other hand, we see that the various appearances these neb- 

 uloe present, are explicable as different stages in the precip- 

 itation and aggregation of diffused matter. We find that 

 comets, alike by their physical constitution, their immense- 

 ly-elongated and variously-directed orbits, the distribution 

 of those orbits, and their manifest structural relation to 

 the Solar System, bear testimony to the past existence of 

 that system in a nebulous form. Not only do those obvious 

 pecuUarities in the motions of the planets which first sug- 

 gested the Xebular Hypothesis, supply proofs of it, but on 

 closer examination we discover, in the slightly-diverging 

 inclinations of their orbits, in their various rates of rotation, 

 and their differently-directed axes of rotation, that tlie 

 planets yield us yet further testimony ; while the satellites, 

 by sundry traits, and especially by their occurrence in 

 greater or less abundance where the hypothesis implies 

 greater or less abundance, confirm this testimony. By 

 tracing out the process of planetary condensation, we are 

 led to conclusions respecting the internal structure of plan- 

 ets which at once explain their anomalous specific gravities, 

 ind at the same time reconcile various seemingly contra^ 



