,50 GEOLOGY. 



descending inclined planes (steam engines were first used in mines *n 

 1804). The pit being sufficiently sunk to a seam of coal, the excavation 

 begins by cutting out the coals literally into what are called galleries. 

 One set of workmen is employed in digging out the coal and another in 

 removing it to the bottom of the shaft, from whence it is drawn up by 

 machinery to the surface. The work of the miners is very laborious, 

 especially where the seams are so thin as to prevent their being in an 

 erect posture. 



The chief accidents to which collieries are exposed are inundations of 

 water, and explosions of gas. The quantity of water which flows into 

 the mines is sometimes quite enormous, and the expense of working it 

 off by pumps of steam power, is one of the heaviest charges of a colliery. 

 It very often happens that a man is drowned by an accidental opening 

 into an old working, filled with water. 



HISTORY OF GAS. 



The discovery of this beautiful means of light is not so modern as one 

 is apt to believe from its recent adoption; for we find in the philosophical 

 transactions of 1667, a paper by one Thomas Shirley, in which he speaks of 

 the burning well nearWigan,in Lancashire, and confutes the opinion that 

 the waters of that well were inflamable, as was then believed ; and adds, 

 that the flame produced, was by the combustion of bituminous fumes 

 issuing from the water, and that it proceeded from the coal-bed which 

 underlies all that part of the country. 



The first published account of making coal gas was by Dr. Hales, in 1 726, 

 who produced 180 cubic inches of gas from 158 grain of Newcastle coal, 

 and this only by way of experiment to prove the elasticity of the gas. 

 A letter in the same publication, in 1739, lays claim to the discovery for 

 one Robert Boyle much earlier, as that person died in 1691. Subse- 

 quently, the attention of many eminent chemists was constantly directed 

 to this object, and to no one does it appear is the merit due of making it 

 an economical means of light but to Mr. Murdoch, who first applied 

 it for lighting his then residence at Redruth, in Cornwall. This was in 

 J792, and five years subsequently he made a similar use of gas in 

 Ayrshire, and in 1798 he partially lighted with it the manufactory of 

 Messrs. Boulton and Watt, at Soho,near Birmingham. In 1802, at the 

 illumination for the peace of Amiens, the whole of the extensive premises 

 at Soho was entirely lighted by gas. Mr. Murdoch in 1806 received the 



