Ex^ilosions in Coal Miiies. 1 7 



now proceed to consider how the recurrence of similar cata- 

 strophes may be obviated in future. 



The Haswell Collieries, where the explosion occurred, are 

 situated about seven miles east of Durham, in that part of the 

 Durham coal field which is overlaid by the magnesian lime- 

 stone, and about two miles within the outer limit or escarp- 

 ment of that formation. In sinking the main shaft, which is 

 155 fathoms deep, they passed through, below the outset or 

 artificial elevation, first, 18 feet of soil, gravel, &c., then 363 

 feet of limestone, red shale, and sandstone of die magnesian 

 limestone formation, and afterwards through 540 feet of the 

 coal measures ; the strata of both formations being so nearly 

 horizontal, that they may be considered as being here in par- 

 allel or conformable position. The accompanying section [as 

 annexed to the original report] of the beds passed through in 

 excavating the shaft, will show that no less than ten seams of 

 coal were met with, varying in thickness from 1 inch to 3 feet 

 7 inches ; and diat at a depth of 925 feet from the surface, the 

 coal called the Hutton seam was gained, which is 5 feet 5 

 inches thick, comprising, first, the top coal of superior quality, 

 4 feet 1 inch thick; secondly, layers of impure coal, 16 inches 

 thick, the upper portion of which, called the brassy coal, is 

 much charged with pyrites ; and the lowest part, of better 

 quality, is said to give out much more gas than the top coal. 

 The dip of the beds is about 1 foot in '24 to the S.E.* 



In the Great Pit, which lies to the S.W. of the LitUe Pit, 

 and is ventilated by the same shafts, a large dike of trap or 

 greenstone was encountered, which had turned the coal into 

 coke, with numerous veins of calcareous spar, for a distance 

 of about 40 yards from the point of contact. Notwithstanding 

 the intrusion of this igneous rock, the strata in general are re- 

 markably undisturbed. In the Little Pit, which we examined 

 carefully, only two or three slips of a few inches, and one fault 

 of two or three feet, appeared. The roof near the entrance 

 shaft was of white sandstone, with occasional seams of mica, 

 but throughout the greater part of the workings, which are 

 about 250 acres in extent, the roof or ceiling is composed of 

 shale, very unbroken and secure, and having given rise to ex- 

 tremely few accidents, by falling in, in the course of the thir- 



* As no part of the section obtained in sinking tlie sliaft of the Haswell 

 Pit was exposed to view at the time of our visit, except the lowest ten or 

 twelve feet, the division into coal measnres and magnesian limestone, and 

 of the latter into upper magnesian and lower red sandstone, with about 

 twenty feet of superficial gravel and clay, has been inferred from the de- 

 scription of the beds given in the miner's section. We have substituted 

 geological names for the miners' terms, as far as we were able to do so. 



Phil. Ma<r. S. 3. Vol. 26. No. 170. Jan, 1845. C 



