122 



SEARCHING FOR COAL IN NEW SITUATIONS, 



joining coal strata in Derbyshire, Leicestershire and Warwickshire.* 

 In confirmation of the opinion here advanced, a saline spring, has 

 very recently been discovered, about four miles north west of Not- 

 tingham ; and coal has been lately found under the red marie and 

 sandstone on the south side of Charnwood Forest, where it had not 

 before been suspected to exist. It may, however be proper to say, 

 that no search of this kind by boring should be undertaken by any- 

 one, to whom the expense, in case of failure, would be a serious in- 

 convenience. 



The dip and direction of the strata in the coal-fields nearest to the 

 estate where the search is to be made, should be well known. If 

 the strata dip towards the estate, it is probable the coal may extend 

 under it : if they dip from it, the search should not be undertaken. 

 To make this intelligible, see Plate III. fig. 3. a. a. a. are a series 

 of coal strata, or, as they are provincially called, coal measures, dip- 

 ping toward the side b. c. c. c. are strata of red marie or sandstone, 

 lying unconformably over the coal strata. Now, according to this 

 arrangement, a search for coal might be successful, though the bed 

 might be at too great a depth to be worked. Whereas, on an estate 

 at D, as the coal strata dip from it, were we to bore to the center of 

 the earth, we could never find the beds 1. 2. 3. 4. If the estate b 

 is situated a considerable distance from a known coal-field, the strata 

 of coal may bend as represented Plate IV. fig. 2. and crop out at a, 

 before they reach the station b, where the trial is made ; and if the 

 outcrop be covered by the red sandstone, this cannot be known but 

 by trial. 



Rock salt or brine springs are most likely to be found by boring 

 in the vicinity of massive gypsum, without regarding the stratifica- 

 tion. As for the districts where the upper secondary strata of lias, 

 oolite, and chalk occur, all search for the regular coal strata must 

 there be fruidess ; as the vast thickness of these calcareous forma- 

 tions precludes the hope of success. 



Coal mines, it is well known, are subject to fatal explosions of what 

 is called the fire-damp, or carburetted hydrogen gas. This gas ap- 

 pears to be generated by the decomposition of iron pyrites in coal, 

 and may often be heard issuing from the fissures in coal-beds with a 

 bubbling noise, as it forces the water out along with it. The choke- 

 damp, as it is called, is either carbonic acid gas, (fixed air,) or the 

 unrespirable residue of air left after explosions, when all the oxygen 

 is consumed. (See Appendix.) 



The regular or great coal formation has never been discovered at 

 a very considerable elevation above the level of the sea : it is gener- 

 ally found towards the feet of great mountain chains, or in the val- 

 leys near to lofty mountain ranges. The geology of large portions 



* Since the third edition of this work was published, eoal has been found under 

 the red marie and sandstone near Manchester. 



