Butterley Company correspondence file on coal mining industry research Including the British Colliery Owners Research Association quarterly bulletin containing article on the Mining Research Laboratory, March 1944, copy of report of the Midland Counties Colliery Owners' Association on coal dust research at Markham Colliery, 1943-1944, copy of questionnaire for the Mining Association of Great Britain Committee on Organisation of Research in investigations by the company, Nov 1944, and two letters on the setting up of a company research department under Mr Fletcher, Apr 1945 Mar 1944-Apr 1945