110 Strictures on the vieivs of Dr. Seller. [Feb., 



place by some peculiar existing arrangements, or else had always 

 existed in the atmosphere; but the assumption is by no means 

 justified when we consider the movements of the organic and in- 

 organic worlds. At one time a peculiar vegetation prevails, but it is 

 really of that kind and character which adapts it to the formation 

 of coal. It may be true or it may not, that the aggregate amount 

 is greater at this period than at a former or subsequent one; the 

 only fact proved by observation is, that the vegetation was pecu- 

 liar; and may have been luxuriant or not; but not that more plants 

 lived at the time. It is not even necessary to say that it was more 

 luxuriant; for time is all that is wanted to supply the amount of 

 matter required to form coal beds, when the proper kind of vege- 

 tation exists. It does not appear that trees grew to a greater size 

 than now — tree-ferns were common, and they were of a large 

 growth; but what then, they were not luxuriant species which 

 had, or which have since existed; they •werestci generis, and size 

 was one of their characteristics. But in this respect they were no 

 greater than many vegetables which live now. In fact the trunks 

 and branches and roots of trees were not greater than the present 

 average of our own forests. 



But then, as we have before remarked, the relation of carbonic 

 acid to water is such that it is impossible it should have accumu- 

 lated in the atmosphere beyond a certain limit, and that limit must 

 have been at about the same standard as the present. We cannot 

 but regard all the speculations respecting the state of the atmo- 

 sphere as unfounded, and unsupported by a single fact, when we 

 consider the nature of carbonic acid itself, and its ready solubility 

 in vapor, and the peculiar character of the vegetation of the peri- 

 od when a greater amount of carbon became fossilized than at any 

 other period. This arose not from quantity but kind, and the 

 peculiar habits of the then existing vegetations. 



Again, we cannot sustain the assumption that the great abund- 

 ance of carbonic acid had an existence coeval with vegetable life; 

 for prior to the existence of the coal period we find no facts which 

 indicated a greater amount than the present, or any other geologi- 

 cal era; hence we are obliged to consider the vegetation of the 

 coal period as an incident in the multitude of geological changes, 

 as peculiar in kind and constitution, not in quantity. 



We will hazard another opinion. It is maintained on all hands 

 that the temperature of the coal period was higher than the pres- 

 ent, or in other words that it was the temperature of a tropical re- 

 gion. Now, may not the very fact of the formation of coal be 

 taken as an argument adverse to the common opinions of geolo- 

 gists? If the climate had been tropical, would not the heat have 

 dissipated the carbonaceous matter? In the dense vegetation of 

 the tropics, where do we find accumulations of carbonaceous mat- 



