Extracts relating to Coal, tSfc. 73 



-'line, that if a stratum can be found in one place, which has a 

 connexion with some other in a second place, and if this othqp 

 has a connexion with another in the third place, &c. ; then, 

 from these separate connexions, the joint correspondence of 

 the whole may be traced, and the strata, which in some 

 places are covered, may be known by their correspondence 

 with those which are exposed to view. 



If by this means the crops of all the strata cannot be seen 

 (which is often the case), and if no coal be discovered by its 

 crop appearing at the surface: yet if the strata that have been 

 viewed consist of those kinds before described, and are found 

 lying in a regular order, it is sufficiently probable that Coal 

 may be in that part of the district, although it be concealed 

 from sight by the surface of the earth or other matter. There- 

 fore, at the same time that the crops of the strata are under 

 examination, it will be proper to take notice of all such springs 

 of water as seem to be of a mineral nature, particularly those 

 known by the name of iron water, which bear a mud or sedi- 

 ment of the colour of rust or iron, having a strong astringent 

 taste. Springs of this kind proceed originally from those 

 strata which contain beds or balls of iron-ore; but by reason 

 of the tenacity of the matter of those strata, the water only 

 disengages itself slowly from them, descending into some 

 more porous or open stratum below, where, gathering in a 

 body, it runs out to the surface in small streams or rills. 

 The stratum of Coal is the most general reservoir of this water; 

 for the iron-stone being lodged in different kinds of shiver, 

 and the Coal commonly connected with some of them, it 

 therefore descends into the Coal, where it finds a ready passage 

 through the open backs and cutters. Sometimes, indeed, it 

 finds some other stratum than Coal to collect and transmit 11 

 to the surface ; but the difference is easily distinguishable ; for 

 the ochrey matter in the water, when it comes from a stratum 

 of Coal, is of a darker rusty colour than when it proceeds 

 from any other, and often brings with particles and small 

 pieces of Coal; therefore, wherever these two circumstances 

 concur in a number of these kinds of springs, situated in ;: 

 direction from each other answerable to the stretch or to tin 

 inclination of the strata, it may be certain the water comes 

 Coal, and that the Coal lies in a somewhat higher situation 

 than the apertures of the springs. 



There are other springs also which come off Coal, and 

 not distinguishable from common water, otherwise than 

 their astringency, and their having a blue scum of an oil\ 

 glutinous nature- swimming upon the surface of the water. 

 These, in common with the others, bring out. particles of Coal, 

 more especially in tin rainj seasons when the springs flow 



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