COAL FIELDS. 285 



of the descent vary in different parts of the field. All the characteristics 

 of the seam as it occurs in Ohio can be found in the western townships 

 of Jefferson county and the eastern townships of Belmont county, where it 

 is mined on a large scale. These characteristics agree closely with those 

 of the seam on the opposite side of the river which have been already 

 described. For an extended account of this field see the chapter of Prof. 

 C. N. Brown in Vol. VI (Chapter X.) 



The Pittsburgh coal in eastern Ohio is a bright, well-jointed and 

 well-faced coal. It is of a highly cementing nature, is moderate in ash, 

 but rather high in the proportion of sulphur that it contains. It has a 

 fair measure of plrysical strength, and consequently is mined in blocks of 

 good average size. It "bears the grief" of transportion fairly well, and 

 the cementing quality of its slack comes in to help it out on every turn. 

 It has the same remarkable steadiness that marks the seam in the Pitts- 

 burgh field. Its thickness in the district named ranges from four and a 

 half to six and a half feet. 



In its structure it shows the same alternations of conditions of origin 

 which the Pittsburgh coal proper everywhere attests. The seam con- 

 sists of a roof coal and a main coal, as already described. As in Penn- 

 sylvania, so in Ohio, the roof coal is a worthless deposit of blended coal 

 and shale, from one foot to four feet in thickness. When exposed in a 

 fresh cut it is hard to believe that it is destitute of value. It is separated 

 by about one foot of fire clay from the main coal and this fire-clay is 

 known as the "draw-slate" among the miners, as in the Pittsburgh field. 



The main coal is in reality a four-benched seam, but in Ohio only 

 two divisions are commonly made of it, viz., an upper and a lower por- 

 tion which are known respectively, as the top coal and the bottom coal. 



The upper bench or top coal, is the "breast coal" of the Pitts- 

 burgh district, There is a "bearing-in" slate, occupj'ing exactly the 

 same position and answering the same office, here as there; but the 

 bottom coal is seldom further subdivided, though, in reality, exactly th e 

 same divisions could be made of it as in the Pittsburgh field, viz., 

 brick coal, lower slate and bottom bench. 



The thickness of the two above named divisions is as follows: 



Upper bench, 28 to 40 inches, averaging 30 inches. 

 Bearing-in slate, \ to 4 inches. 

 Lower bench, 24 to 28 inches. 



The brick coal, so called, of the Pennsylvania field, ranges in Ohio 

 from 8 to 14 inches ; but, as already stated, it is not commonly separated 

 from the coal of the lower bench, proper. 



It is difficult to give the average composition of the Pittsburgh coal 

 of eastern Ohio because of the great differences that obtain in the 

 methods of mining it. The seam, as has been shown, carries three 

 dividing bands of slate, and when carelessly mined, the coal is contami- 

 nated by more or less of this substance, while careful mining would 



