THE ASTRONOMICAL HISTORY OF WORLDS. 571 



Having thus to some extent prepared the way for a more strictly 

 chemical and physical appreciation of vital phenomena, we will pro- 

 ceed, in the next paper, to inquire by what agencies the chemical com- 

 position and decomposition of the living substance are effected. 



[To be continued.] 



THE ASTRONOMICAL HISTORY OF WORLDS. 



By Professor DANIEL VAUGHAN. 



THE information which geologists derive from the evidences of 

 organic remains does not wholly satisfy the keen appetite of edu- 

 cated minds for a knowledge of the mysteries of Nature and the 

 revolutions of past times. The relics disentombed from our globe give 

 no clew to its origin ; and they throw but little light on the great physi- 

 cal events which transpired before life appeared on its surface. There 

 are, however, reasonable hopes that the records which are wanting on 

 this earth may be supplied from the heavens ; and that some general 

 cause, to which the numerous orbs of celestial space are indebted for 

 their existence, may be revealed from the peculiar character of their 

 movements, or from some of the mysterious phenomena which they occa- 

 sionally exhibit. In associating his researches with those of the geolo- 

 gist, and in taking cognizance of the great events in the course of time, 

 the astronomer may enhance the value of the inquiries which more com- 

 monly fall to his lot. A knowledge of the condition of the earth in 

 past ages is calculated to give much insight into the state of similar 

 orbs in remote space ; and opinions of the habitability of other planets 

 must be more valuable in proportion as geology and terrestrial physics 

 show more definitely how our globe acquired and how long it can retain 

 the conditions necessary for the maintenance of life. 



The tendency to widen the range of its inquiries and to speculate 

 on the origin of the celestial bodies cannot be considered as a new 

 feature of astronomy. The sudden appearance of the new stars, in 

 1572 and 1604, led Tycho Brahe and Kepler to the belief that the cos- 

 mical vapor or exceedingly rarefied matter of space was occasionally 

 condensed to form great stellar orbs. These crude notions of the quick 

 growth and ephemeral life of great suns were gradually replaced by 

 views less repugnant to reason and experience. In the succeeding 

 age the faintly luminous spots which the telescope revealed in the 

 heavens were regarded as primitive chaotic matter exceedingly rarefied 

 by intense heat, and they were supposed to be undergoing a slow cool- 

 ing and a gradual condensation which would ultimately convert them 

 into suns or into planetary systems. This opinion, however, though 



