Onllwyn No. 1 Colliery. Cornish Four Feet Seam. Size yields of Run of Mine Coal produced before and after introduction of Pulsed Infused Blasting (318/59/9) Jan 1959

  • This material is held at
  • Reference
      GB 216 D/D PRO/NCB/6/544
  • Dates of Creation
      Jan 1959
  • Language of Material
      English
  • Physical Description
      1 file