178 CARBONIFEROUS. 



Coal was worked in England as early as a.d. 852 in the 

 Northumberland Coal-field, but not to any extent until the 

 thirteenth century. In 12 10 we have the first record of a Coal- 

 mine in England; in 1239 Henry III. granted a charter to the 

 freemen of Newcastle-on-Tyne for liberty to dig coals ; and shortly 

 afterwards coal was sent to London by ship, and known as ' Sea- 

 borne coal.' It was not, however, until about the 17th century 

 that coal was generally used in London. Coal, however, had been 

 known many years before the Christian era ; it was known to 

 Theophrastus about 238 B.C. It was likewise known to the Ancient 

 Britons in Lancashire, and probably in Northumberland, and to the 

 Romans in a.d. 60. 



In early times the coal was quarried at the surface, but as the 

 supply that could be worked in this way was in time exhausted, it 

 was necessary to have recourse to mining. 



There are two systems of working the coal underground, termed respectively 

 the ' Pillar and Stall,' and the ' Long Wall ' systems. In the former case the coal 

 is worked out in square galleries called stalls, while pillars or posts of coal are left 

 to support the roof : in the latter case long galleries are driven to the full extent 

 of the mine, and the coal is then worked out as far as possible in the intermediate 

 spaces. The latter plan is usually adopted in working thin coals. 



Many faults and disturbances affect the Coal-measures in various 

 places : some of these will be alluded to in the sequel. These 

 faults frequently do not affect the overlying Secondary strata. 



One of the deepest mines in England is at Rose Bridge, near 

 Wigan, 815 yards; but the deepest mine is that at Ashton Moss 

 Colliery, also in Lancashire, 897 yards. At the depth of 860 yards 

 the temperature was 78° Fahr. 



Much danger arises in the mines from the escape during the 

 working of the imprisoned gas called 'fire-damp' (carburetted 

 hydrogen), which is highly explosive when mixed with air, 

 and when ignited produces the much dreaded ' choke-damp,' 

 ' after-damp,' or ' black-damp ' (carbonic acid gas) ; so that a good 

 system of ventilation and the use of the Davy lamp are very 

 necessary. In some few districts, as near Radstock in the 

 Somersetshire Coal-field, ' fire-damp ' is unknown, and the miners 

 work with naked candles. It has, however, been shown by Mr. 

 W. Galloway that a mixture of fire-damp and air becomes inflam- 

 mable at ordinary pressure and temperature when charged with 

 fine coal-dust ; and to this cause many explosions may be 

 attributed.^ Danger of another kind sometimes arises from what 

 are called " creeps," when the pressure of the strata on the sides of 

 the passages or upon the pillars causes the floor to swell up,^ 



^ See also Report of Commission on Accidents in Mines, noticed in Nature, 

 April 15, 1886. 



* For further details on the subject of Coal, its history, uses, and the method of 

 working it, see \V. W. Smyth, Treatise on Coal and Coal Mining, edit. 2, 1872 ; 

 E. Hull, Coal-Fields of Great Britain, edit. 4 ; R. Meade, The Coal and Iron 

 Industries of the United Kingdom, 18S2 ; Coal, its History and Uses, by Professors 

 A. H. Green, L. C. Miall, and others, 1S78; and the Rev. T. Wiltshire, History 

 of Coal, 1878. 



