1846— 1S7S] MISCELLANEOU 2\; 



in the amount of nitrogen at different depths in the suj 55' 



mould, and hen- worms may have playi trt. I wish that 



the problem had been b I ob ervin ibly 



I might have thrown some litt ht on it, which would h 



pi ised me greatly. 



VII I. MlSCl LLANEOUS, [846 ; 



The following tour letters ted with the origin 



of coal. 



To J. D. Honker. 



Down, May [1846]. 

 I am delighted that you arc in the field, ising 



or palaeontologising. I beg you to read the two ! 

 account; of the Coal-fields of \. America 1 ; in my opinion 

 the}- arc eminently instructive and si; I can lend 



you their resume* of their own labours, and, indeed, I do not 

 know that their work is yet published in full. L. Horner 2 

 gives a capital balance of difficulties on the Coal-theory in 

 his last Anniversary Address, which, if you have not n 

 will, I think, interest you. In a paper just read an author 3 

 throws out the idea that the Sigillaria was an aquatic plant 4 

 — I suppose a Cycad-Conifer with the habits of the man- 

 grove. From simple geological reasoning I have for some 

 time been led to suspect that the great (and great and 

 difficult it is) problem of the Coal would be solved on the 

 theory of the upright plants having been aquatic. But even 

 on Mich, I presume improbable notion, there are, as it stril 

 me, immense difficulties, and none greater than the width 

 of the coal-fields. On what kind of coast or land could the 

 plants have lived ? It is a grand problem, and I trust you will 

 grapple with it. 1 shall like much to have some discussion 

 with you. When will you come here again? I am very sorry 

 to infer from your letter that your sister has been ill. 



1 On the Physical Structure Appalach . by W. B. ami 



H. D. Rogers. Boston, 1 845. Sec also . by 



II. D. Rogers. 4 vols. London and Philadelphia, 1S43. 



'-' Quart. Journ. . Vol. II., 1846, p. 1 



3 u On the Remarkable Fossil Trees lately discovered near St. Helen 

 By E. W. Binney. Phil. Mag., Vol. XXIV., p 1 .4- On p. 173 



the author writes : "The .'; or 6 io, whichever name is to 



be retained .... was a tree that undoubtedly grew in wati 



* See Life and Letters, I., pp. 356 et 1 



