356 SCIENCE PROGRESS. 



suggestive expressions of opinion, far in advance of the 

 general thought of his day, refers to the occurrence of up- 

 right stems in the Coal- Measures, and realises the possibility 

 that a vertical position may sometimes be the result of the 

 action of water, and that it is not necessarily a proof of 

 growth on the spot. 1 Within the last few years the elaborate 

 memoirs by French geologists on the coalfields of Central 

 and Northern France, have clearly demonstrated that in 

 certain cases the true explanation of coal formation must be 

 sought in the direction suggested by some writers in the 

 early part of the century. The remarks by Link with 

 reference to erect stems are especially interesting in view 

 of the opinions recently expressed by Fayol 2 on the same 

 subject. 



We may approach the subject of coal from various points 

 of view, and any one of these suggests diverse lines of in- 

 quiry which have not as yet been thoroughly exhausted. 



We may turn our attention to the numerous questions of 

 special geological interest which centre round the nature and 

 mode of origin of the coal seams ; we may study the com- 

 position of coal in the laboratory with a view to solving the 

 problems connected with the conversion of vegetable ddbris 

 into a hard and compact rock ; we may, on the other hand, 

 take up the investigation of the coal strata from the point of 

 view of botanists, anxious to learn something from the frag- 

 mentary remains in the Palaeozoic herbaria as to the lines of 

 descent of existing plants ; and, finally, we may make more 

 or less feeble attempts to picture to ourselves the actual 

 geographical and climatal conditions which obtained during 

 the building up of the great series of strata included in 

 the Coal- Measures. The immediate purpose of this article 

 is to draw special attention to some comparatively recent 

 researches into the conditions of coal formation. The usual 

 explanation of the manner of accumulation of coal seams, 

 which we are accustomed to in English text-books, has 



1 Link, p. 44. 



2 The works of the various authors will be found in alphabetical order 

 in the bibliography accompanying this article. 



