 The guttural r sound can, however, still sometimes be detected, especially amongst elderly populations in more rural areas.While in theory pitmatic was spoken throughout the Great Northern Coalfield, from Ashington in Northumberland to Fishburn in County Durham, early references apply specifically to its use by miners especially from the Durham district (1873)  and to its use in County Durham (1930).Dialect words in Northumberland and Tyneside, including many specific to the coal-mining industry, were collected in the two volumes of "Northumberland Words" by Oliver Heslop in 1892 and 1894.