244 



lined with fire brick, and contain, according to the n^ost approved prac- 

 tice, from six to eight tons of coal each. Influenced by the especial 

 object of consumption, the coke is roasted from fo to 90 hour?, produ- 

 cing, according to the quahty of the coal and the duration of burning, 

 from 40 to 55 per cent of coke. The said ovens cost from £30 to £50 

 each," ($150 to $200.) 



In a second edition of the same work, M. Dunn states : 



" Since my history of the coal trade appeared in 1844, many and 

 great revolutions have taken place throughout the country, in respect to 

 the demand and supply of coals. In aid of the general trade and the 

 inferior collieries, three great and unforeseen events have occurred, viz : 

 the extension of the steam coal consumption ; the immense increase of 

 the con-sumption of coke and gas ; and the general manufacturing con- 

 sumption. 



" The extraordinary increase of the coke trade from the county of 

 Durham deserves especial attention, inasmuch as many large collieries 

 in the Tanfield, Brancepeth'and Crook districts, are being worked 

 chiefly for the making of coke for the locomotion, home trade, and for- 

 eign consumption ; and it is no unusual thing for a single colliery to 

 possess 300 and 400 ovens. The seams of coal in these collieries are 

 of so very soft a"] nature that they are fit only for the making of 

 coke or the production of gas. * * * * 



" From the superior quality and density of the coke made in this part 

 of the country, it fonns the grand subject of consumption throughout 

 the greatest part of the kingdom, and even in Yorkshire and Lancashire, 

 where many of the seams are of a pure coking quality." 



The thorough chemical analysis and practical experiments made of 

 late years, in England, to test the comparative usefulness of its various 

 coal beds, have been forced upon the colheries by the pressing demand 

 for coke for the use of locomotive engines, iron works, and innovating 

 improvements in her numerous branches of manufacture ; and it would 

 seem that even there, where (in the language of the late Professor 

 Johnson, of Philadelphia) " the coal deposits of the small island, which 

 would itself scarcely cover one of the coal fields of the United States, 

 have contributed to the power and influence of one of the most com- 

 mercial nations of the world, and aftbrded the chief means of carrying 

 her conquests to the remotest part of the globe," the value and power 



