2 STEVENSON— FORMATION OF COAL BEDS. [April 21. 



tered in publications of many societies in six or more languages ; 

 many were merely separate pamphlets, now almost inaccessible. 

 Great scientific libraries are few and they are beyond reach of the 

 ordinary field-worker; while college professors and men connected 

 with official surveys rarely have leisure needed for thorough re- 

 search. The necessity for prompt publication, that fellow workers 

 may have the advantage of one's results, makes long preliminary 

 study almost impossible, in some cases almost unjustifiable. 



The writer, looking forward to preparation of a monograph on 

 formation of coal beds, has examined many hundreds of publications 

 varying from mere notices to ponderous quartos and this preliminary 

 work is still far from complete. During the examination, he has dis- 

 covered not only that there is little new under the sun but also that 

 much, which is good and important, soon passes from men's minds. 

 He has discovered also that owing to quotation at second-hand, with- 

 out verification, some conclusions ofifered by the earlier students have 

 been misunderstood or even misinterpreted, so as to discredit the 

 authors. He has become convinced that a systematic presentation 

 of conclusions reached by his predecessors would not be useless or 

 unacceptable; it would exhibit the gradual development of opinion 

 and it would lead to proper appreciation of investigations made and 

 conditions, which, in this day, would be regarded as unfavorable ; it 

 would aid the students hereafter by indicating the road along which 

 to pursue his preliminary examination. Such presentation is offered 

 in the succeeding pages. 



In preparing this historical summary, the writer, recognizing the 

 necessary limits of space, is compelled to note only such publica- 

 tions as deal especially with the topic under consideration ; and of 

 those, only such as are the outcome of direct study. The reader 

 may be disappointed by the omission of some authors and by the 

 admission of others ; but this is unavoidable. Many important re- 

 flections have been made by writers incidentally ; those will be noted 

 in the final discussion. No reference to opinions respecting the 

 origin of coal is given, except in cases where that question is basis 

 of the author's conclusion res]X"cting the mode of accumulation. 



The plan of the summary may be open to criticism. The 



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