The D.M.S. Watson Coal Ball sectioned microscope slide preparation imagery presented here was sampled between 1903 and 1912 from coal seams across England (Cheshire, Lancashire, Yorkshire, Gtr. Manchester & others) and Scotland (Fife). Coal Balls form when plant material becomes mineralised rather than turning into coal. Such preparations can preserve whole plants and even cellular detail. This material held at UCL was collected from horizons in coal measures that date from 325,000,000 to 280,000,000 years ago (the Upper Carboniferous Period) by D.M.S. Watson and Marie Stopes.