1874.] 191 [Whittlesey. 



tract, are only 25' to 30' apart, and in one mine of No. 6 the varia- 

 tion of the floor is 25'. Unavoidable errors of the barometer exceed 

 this. 



Close topographical work and exact physical profiles are indis- 

 pensable in such a region, to give confidence in the results. In those 

 which I give there are admitted sources of error, when viewed as 

 strictly mathematical determinations. The bearings and distances are 

 taken from maps ; and the elevations are frequently taken only to the 

 mouth or entry of the mines, and are not the average of the seam. 

 Within the perimeter of the triangles the beds are waving and 

 warped surfaces, with domes and valleys, but having a surface which 

 approximates to a plane, some parts above and others below, with a 

 plus or minus difference of 1 5' to 20'. But admitting these defects, 

 which might have been measurably cured by the Survey, it cannot be 

 that such errors are very large, or are all in one direction. It will 

 appear that among hundreds of elevations, after extending a series of 

 triangles over the field, locally and generally, the results show no 

 instance of a bed of coal dipping to the west or northwest. 



Triangula tions. 



No. 1. Coal Seam No. 1. 



Warsaw, northwest part of Coshocton Co., Darling's bank, 348' 

 (W.) ; Cameron's bank, three miles north of Millersburg, Holmes Co., 

 365'; and Union Company's sump, near Massillon, Stark Co., 340' 

 (W.) ; length of three sides, eighty-one miles. 



These figures represent the floor of the series, which is over this 

 space, nearly level, as I showed in 1869. The inclination is very 

 slight, only two feet per mile, and its direction is south 55° east. 



No. 2. Coal Seam No. 6. 



Nashville, Holmes Co., 688' (N.) ; Dundee, Tuscarawas Co., 558' 

 (N.) ; Coshocton, Coshocton Co., 248' (N.) ; length of sides, sixty-nine 

 miles ; bearing of the strata north 64° east, dip south 26° east; rate 

 22' per mile, neglecting fractions. 



If No. 6 is persistent, it dips beneath the barren measures, and the 

 Pittsburg seam on the southeast, in Guernsey and Harrison Counties. 

 If an undulation exists in those counties it has not affected the Pitts- 

 burg seam. It is, however, far from conformable to the floor of the 

 series beneath it. Because Patterson's mine at Dundee, 558' A., 



