44 



THE WONDERS OF GEOLOGY. Lect. I. 



which appears to govern the stupendous celestial phenomena 

 that are constantly taking place.* 



13. Various states of the nebulae. — Some of the 

 nebulae appear as mere clouds of attenuated light — others 

 as if curdling into separate masses — while many seem 

 assuming a spheroidal figure. Others again present a 

 dense central nucleus surrounded by a luminous halo; and 

 a series may thus be traced, from clusters of round bodies 

 with one or more increased points of condensation, or of 

 central illumination, to separate nebulae with single nuclei, 

 and with rings, to a central disk constituting a nebular 

 star ; and finally to an orb of light with a halo like the 

 sun ! 



In the comets, those nebular bodies which belong to our 

 own and other systems, we have evidence that even in the 

 most diffused state of the luminous matter, the masses 

 which it forms are subservient to the laws of orbicular 

 motion : of this fact an interesting proof is afforded by 

 Encke's comet (Lign. 5), that mere wisp of vapour, which in 

 a period but little exceeding three years, revolves around 

 the central luminary of our system. 



This beautiful theory of Laplace, and' of Herschel, 

 explains by an easy and evident process the formation of 

 planets and satellites, and accounts for the uniform direction 

 of their revolutions ; and not only is it inferred that such 

 is the law which the Creator has established for the main- 

 tenance and government of the Universe, but also that upon 

 mechanical principles, such nebulae must of necessity con- 

 solidate into planetary bodies. 



* Although by the enormous powers of the telescope constructed 

 by the Earl of Rosse, it has been ascertained that several of Herschel's 

 nebulae are clusters of stars, and it is therefore probable that other 

 supposed nebular masses may be brought into the same category, the 

 theory explained in the text will only be modified, not disproved 

 thereby. 



