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the enormous quantities and sizes of the plants which compose 

 the Coal strata, we must inquire into the forces which are 

 concerned in the organization of plants. A greater quantity 

 of carbonic acid in the atmosphere, together with an increase 

 of terrestrial temperature, have been assigned as sufficient 

 causes for this luxurious vegetation ; but from the researches 

 of Dr. Draper, Professor in the University of New York,, 

 light, or rather the tithonic rays, are the active agents 

 in the growth of all vegetation. That gentleman had 

 suggested that the sun is one of those periodic stars, the 

 light of which undergoes secular changes ; that for a series 

 of years or of centuries, it increases in brilliancy, and then 

 fades away; that, affected by this, the rate of vegetable 

 growth, the character of animal life, the constitution of the 

 atmosphere, is simultaneously changed in all the attendant 

 planets. And aimong the stars these periodic variations do 

 take place. It signifies nothing that these periods are short. 

 In the constitution of the universe, no value is attached to 

 time. With men, whose period of action is embraced in a 

 few years, the different events are circumscribed by measured 

 spaces. But in the administration of the universe, the case 

 is different ; in eternity there are no limits of duration, and 

 time can be expended without loss or detriment. In the 

 revolution of one system of stars round another, millions of 

 centuries are required, and they are consumed. And in the 

 case we are considering, the glowing and fading away of one 

 star may be accomplished in a few days, but inconceivably 

 greater periods may be wanted for the same events in another. 

 Even philosophers are too prone to believe that, by the short 

 spaces of human life, or the history of nations, they can 

 mark out periods in eternity ; but whether we consider the 

 scale of space, or of time, on which the universe is con- 

 structed, we see that our minds are so constructed as to be 

 equally unable to appreciate either extremity; that we can 



