600 THE POPULAR SCIENCE MONTHLY. 



(helium) which hitherto has been unknown on the earth. Moreover, 

 also, the inner structure of the sun, the distribution of its incandescent, 

 liquid, and gaseous parts, its luminous and colored envelop, the nature 

 of its spots and protuberances all this is no longer a play-ground for 

 fantastic imaginings, but the subject of exact research. Since the 

 great eclipse of 1868, Lockyer and Janssen, Zollner, Huggins, and 

 Father Secchi, have observed, day after day, storms, whirlwinds, 

 flame-sheaves, outbursts of burning hydrogen to the height of 20,000 

 miles : thus has been developed an entirely new science the meteor- 

 ology of the sun. Moreover, on other obscure regions of the heavens, 

 on the physical and chemical conditions, even on the laws of the move- 

 ments of the fixed and double stars, on nebuloe and milky ways, on 

 planets and comets, on zodiacal and northern lights, has spectrum 

 analysis thrown its enlightening rays. No less by rigorous mathe- 

 v matical method, through which astronomy, even at an earlier period, 

 had been brought to a certain amount of perfection, has she in the 

 most recent time enjoyed an unexpected triumph, by solving, through 

 the researches of Schiaparelli, the riddle of the comets, in being able 

 to recognize the identity of their nature with that of the swarms of 

 shooting-stars whose remarkable brilliancy long ago made them uni- 

 versally known. 



II. 



During the last quai'ter of a century, the history of the formation 

 of our earth has assumed a new aspect. When the " Cosmos " appeared, 

 the opinion prevailed that our earth, once a globe of liquid fire, became 

 covered with a crust of congealed scoria?, on which, by-and-by, the first 

 animal- and plant-life made its appearance. After an almost infinite 

 length of time, during which the Silurian, Devonian, Carboniferous, 

 and Permian strata were deposited, a terrible catastrophe, affecting 

 simultaneously the whole earth, so completely destroyed the first 

 palaeozoic life, that not a single species survived the universal devas- 

 tation. Upon the lifeless expanse, it was supposed, appeared then 

 the Secondary Fauna and Flora, entirely unconnected with and dif- 

 ferent from the extinguished one, until, after frequent repetitions 

 of the same process at longer or shorter intervals, man made his ap- 

 pearance, and along with him all existing plants and animals: with 

 him begins the Historical Period, whose duration has not exceeded 

 6,000 years. The causes of these world-wide revolutions geology 

 sought in the violent reaction of the molten interior against the once 

 extremely slender crust. 



In opposition to these views, the opinion peculiarly associated with 

 the name of Lyell has made way, that no violent revolutions, return- 

 ing at intervals, destroyed the external structure of the earth and all 

 the life it sustained, but that all changes even in the earliest times 

 affected only the earth's surface, and that these could only be the re- 



